heath and medicine

1. Radiological imaging of soft tissue masses of the wrist and hand.
Dr/ ABD ALLAH NAZEER. MD.

3. Benign lesions
Ganglion cyst
Ganglion cysts are the most common lumps encountered in the hand
and wrist region. They tend to occur in young adults and are three
times more frequent in females. They are thought to represent
degeneration of connective tissue caused by chronic irritation. The
most common location is in the dorsum of the wrist where they usually
arise from the scapholunate joint. Less typical sites include the volar
aspect of the wrist from the radio-scaphoid or scapho-trapezial joint,
at the metacarpophalangeal joint in relation to flexor tendons and
distal interphalangeal joints. MR shows a well-circumscribed unilocular
or multilocular lesion of fluid signal, although the signal may vary
depending on the amount of proteinaceous contents. Mild rim
enhancement of the capsule may be seen, but there is usually no
enhancement of internal contents. Differential diagnoses include
synovial cysts and other cystic lesions such as epidermal cysts.

4. Ganglion cyst. MR shows a smooth, well-circumscribed lesion within the
thenar musculature of homogeneous low signal on T1w sequence (A, arrow)
and high fluid signal on T2w-FS sequence (B, arrow). No invasion into
adjacent structures is seen. There is minimal rim-enhancement (C, arrow).

6. Volar ganglion cyst. a Coronal FS T2-WI. Note a poly lobular hyperintense cystic structure
with a small stalk-like connection to the adjacent scaphotrapezial joint (arrow). b Axial
FS T2-WI. The cyst is well delineated and is of high signal intensity (arrowheads).

7. (a) Dorsal ganglion. Axial T2 weighted image demonstrating a well-defined,
fluid signal, lobulated mass arising from the region of the dorsal scapho-
lunate ligament (arrow). The lunate (Lu) and scaphoid (Sc) are labelled. (b)
Axial T1weighted image demonstrating an intermediate signal mass.

8. Epidermal cysts are common hand lesion resulting from
proliferation of epidermal cells within a confined space in the
dermis. They can be congenital, a result of occlusion of the
follicles by adjacent inflammation or tumour, or associated with
human papilloma virus infection. True epidermal cysts result from
implantation of epithelial squamous into the dermis because of
trauma. MR shows a well-circumscribed lesion of fluid signal in
the dermis or subdermis. However, signal on the T2w sequence
may be variable depending on the amount of internal keratin
debris. Rim enhancement can be seen. Lack of central
enhancement is key to distinguish epidermal cysts from more
sinister lesions such as neurogenic tumours or sarcomas,
particularly if heterogeneous signal is present because of internal
debris. They may also be mistaken for ganglion cysts if located
close to the joint or tendon sheath.

9. Epidermal cyst. MR shows a smooth well-circumscribed subcutaneous lesion superficial to
the thenar musculature with low signal on T1w (A, arrow) and high fluid signal on T2w-FS
sequence with faint low-signal foci within representing squamous / debris (B, arrow).
Minimal rim-enhancement is seen with no significant internal enhancement (C, arrow).

10. Subcutaneous epidermoid cyst with involvement of the adjacent bone of the terminal phalanx of the right fifth finger. a
Plain radiograph showing a well-defined osteolytic defect at the radial side of the distal phalanx. Note cortical destruction
of the radial cortex. b Coronal SE T1-WI. The lesion is of intermediate signal intensity (arrows) with some internal areas of
relatively high signal. c Coronal TSE T2-WI. High signal intensity of the lesion (arrows). d Coronal FS SE T1-WI after
intravenous injection of gadolinium contrast medium. There is only subtle peripheral enhancement (arrows) of the lesion

11. Fibromas of the tendon sheath (FTS) are uncommon lesions
thought to be a reactive fibrosis. It has a peak incidence at 20–50 years
old, is three times more common in males, and 82 % of them occur in the
hand and wrist region. The low signal on all MR pulse sequences expected
of a fibrous lesion is not always seen. FTS are generally well defined and of
low signal on T1w sequence. Signal intensity on T2w sequence and
contrast enhancement is more varied and heterogeneous, likely reflecting
varying proportions of fibrous and cellular tissue. Differential diagnoses
include more sinister lesions such as soft tissue sarcomas and giant cell
tumours of the tendon sheath (GCTTS). FTS and GCTTS are believed to
represent two end points of a single clinicopathological entity based on
histological studies, the former with a predominance of myofibroblastic
markers while the latter with a predominance of macrophage-related
components. They can be differentiated based on certain imaging
features. On GRE sequence, GCTTS usually demonstrates susceptibility
artefacts, which are absent in FTS. Bony scalloping is also often seen in
GCTTS but rare in FTS, and while both are most commonly located in the
hand, GCTTS is more likely to be found in the feet compared to FTS.

12. Fibroma of the tendon sheath. The mass appears mildly hyperintense to skeletal muscles
on T1 (a) and T2-weighted fat saturated (b) images. Areas of low signal intensity within
the lesion (orange arrows) are attributable to the collagenous nature of the tumor. The
mass shows mild post contrast enhancement (blue arrow) on axial T1-weighted fat-
suppressed image (c). No susceptibility changes are noted on the gradient image (d).

14. Fibroma of Tendon Sheath.

15. Calcifying aponeurotic fibroma of dorsal wrist.

16. Focal nodular synovitis is a benign synovial neoplasm commonly
occurring around the small joints of the hands and feet. They
represent the localized form of pigmented villonodular synovitis
(PVNS), which usually occurs around larger joints, particularly the
knee. Histologically focal nodular synovitis can be confused with
PVNS and GCTTS. All three entities are characterised by
multinucleated giant cells and macrophages with varying degrees
of hemosiderin deposition, but merely represent various forms of
synovial proliferation. Presence of hemosiderin results in
susceptibility artefacts on GRE sequence in all three entities, but is
usually most extensive in PVNS, which also shows frond-like
projections into the joint. On MR, focal nodular synovitis is usually
well defined, isointense or slightly hyperintense to muscle on T1w
sequence and of low signal on T2w sequence because of collagenous
stroma. In larger lesions, variable signal on T2w sequence and
heterogeneous enhancement may be seen because of proliferating
capillaries.

17. Focal nodular synovitis. MR shows a lobulated subcutaneous nodule of homogeneous low
T1w signal over the dorsal aspect of the third metacarpophalangeal joint abutting underlying
extensor tendon (A, arrow). The lesion is also of low signal on T2w-FS sequences (B, arrow).
No bony destruction is seen. There is no significant contrast enhancement (C, arrow).

18. Localized extra-articular PVNTS of a flexor tendon
sheath of the index finger in a 25-year-old man
with a slowly enlarging soft-tissue mass for 2
years. (a, b) Axial T1- weighted (650/19 in a,
800/17 in b) precontrast (a) and fat-suppressed
postcontrast (b) MR images show an intermediate-
signal-intensity soft-tissue mass (*) adjacent to
and partially encasing (arrows) the flexor tendon
(T). The mass is diffusely enhanced in b. (c) On a
sagittal T2-weighted (5000/92) MR image, the
mass (*) has heterogeneous, predominantly
intermediate signal intensity without prominent
low-signal-intensity areas. T = tendon.

19. Extra-articular PVNTS diffusely involving the entire tendon sheath in a 24-year-old woman with a
slowly enlarging mass in her thumb. (a) Axial T1-weighted (450/13) MR image shows an intermediate-
signal-intensity soft-tissue mass (*) that encircles the flexor pollicis tendon (arrow). (b) Coronal T1-
weighted (400/13) fat-suppressed postcontrast MR image reveals diffuse enhancement of the
extensive tenosynovial involvement (arrowheads), which extends circumferentially about the tendon
(T) from its attachment at the base of the distal phalanx (P) of the thumb to the carpal tunnel (C).

20. Pigmented Villonodular Synovitis (PVNS) of the forearm and wrist. Image T1–weighted
(a). High signal on T2-weighted image (c) and T1–weighted post-contrast (b-d) .

21. Nodular fasciitis is a benign reactive fibroblastic lesion usually in
young adults, thought to be associated with trauma, most commonly
seen in the upper extremities. On MRI, it shows low signal on T1w
sequence and heterogeneous, mixed high signal on T2w sequence,
depending on the distribution of myxoid and fibrous components.
Lesions with predominantly cellular content or myxoid degeneration
appear hyperintense on T2w sequence while those with highly
collagenous contents are hypointense. Contrast enhancement pattern is
most commonly diffuse but it may also be peripheral in lesions with cystic
degeneration. Nodular fasciitis can be easily confused with a malignant
lesion given the clinical presentation of a rapidly growing lump and
imaging findings of inhomogeneous signal characteristics and
enhancement, lobulated borders and crossing of compartments.
Differential diagnoses include neurogenic tumour, soft tissue sarcoma or
early stage of myositis ossificans especially when it occurs in an
intramuscular location. Complete local excision is usually curative and
hence careful histological analysis is necessary to avoid misdiagnosis
and unnecessary radical surgery.

22. Nodular Fasciitis. a) MRI T1 axial image shows a well circumscribed lobulated mass of
intermediate signal intensity along the volar aspect of wrist in close relation to the flexor carpi
ulnaris tendon sheath (orange arrow). The mass also abuts the flexor retinaculum (blue arrow)
though there is no infiltration of flexor tendons lying deep to it. It shows heterogeneous high
signal on (b) T2 (F/S) axial image. Intense enhancement is seen on (c) T1 post contrast image
with an irregular non enhancing area within it. No susceptibility is detected on the (d) gradient-
echo sequence which may help in differentiating it from giant cell tumor of the tendon sheath.

23. Nodular fasciitis in finger simulating soft tissue malignancy.

24. Lipomas are the most common tumour in the human body
usually developing in later adult life. A rather suggestive
sonographic feature is an encapsulated hyperechoic lesion
with fine linear internal echoes. Characteristic MR features
of a well-circumscribed lesion that is hyperintense on both
T1w and T2w sequences with homogeneous signal loss on
the STIR or fat-saturation sequences allow confident
diagnosis. It can be difficult to distinguish among benign
lipomas, atypical lipomatous lesions or well-differentiated
liposarcoma on imaging. Findings of thick enhancing
septation or a nodular component should raise suspicion
of the latter. Interestingly, findings of infiltrating or
insinuating margins tend to suggest benign lipoma rather
than liposarcoma.

26. Lipoma. MR shows a well-circumscribed lobulated subcutaneous lesion over the
palm, hyperintense on T1w sequence crossing compartments, insinuating
between the flexor tendons (A, arrow). There is homogeneous signal loss on T2w-
FS sequence (B). Faint enhancement of thin internal septae is noted (C, arrow).

27. a) Lipoma. Coronal T1 weighted image demonstrating a well-defined homogeneously high
signal mass (arrowheads) in the thenar eminence. (b) Coronal short tau inversion recovery
(STIR) image demonstrating a low signal mass (arrowheads) in the thenar eminence.

28. Lipofibromatous hamartomas are rare benign
tumours usually involving the median nerve at the wrist. It
commonly presents as a progressively enlarging lump or
symptoms of compressive neuropathy, most occurring in
the first 3 decades of life. Excessive fibroadipose tissue
proliferates along the perineurium, surrounding the nerve
bundles within the nerve sheath. This gives the lesion its
pathognomic appearance on MR imaging. MR typically
shows a fusiform swelling representing the enlarged nerve
with serpiginous, “spaghetti” or “cable”-like appearance,
representing the low-signal axons surrounded by fatty
tissue. Management is usually conservative as surgical
resection is almost always accompanied by neurologic
morbidity.

29. Fibrolipomatous hamartoma. MR shows a well-circumscribed lobulated
subcutaneous lesion within first web space, hyperintense on T1w sequence with
curvilinear internal signal voids (A, arrow). On T2-FS sequence the lesion shows
homogeneous signal loss with hyperintense curvilinear structures coursing
through the centre of the lesion (B, arrow). These structures show enhancement
(intra-operatively confirmed to represent neurovascular components of the lesion)
while the rest of the lesion does not show significant enhancement (C, arrow).

30. a) Fibrolipomatous hamartoma of the median nerve. Axial T1 weighted image
demonstrating a mass (arrows) comprised of low signal foci surrounded by fatty
signal, the ‘‘co-axial cable’’ sign. (b) Coronal T1 weighted image demonstrating
separation of nerve fascicles by fatty tissue (arrows), the ‘‘spaghetti’’ sign.

31. Fibrolipomatous Hamartoma of the Median Nerve. Show a interposition
of fat between the nerve fibbers, and increase size diameter.

32. Hemangiomas are the fourth most common hand tumour, usually
occurring in the younger age group, with a slight female predominance.
On MR, they are typically very hyperintense on T2w sequence and show
lobulations, septations or low-signal foci much more frequently than other
soft tissue masses. Marked hyperintensity of the lesions on T2w sequence
is due to increased fluid content secondary to stagnant blood flow in
vessels. Signal on T1w sequence is usually iso- to hyperintense compared
to muscle because of the presence of fat and blood products. Lesions that
are typically larger than 2 cm contain various amounts of fat, smooth
muscle, myxoid stroma, thrombi and hemosiderin. Susceptibility artefacts
on GRE sequence may be due to Phleboliths or blood products, and these
can be distinguished on plain radiograph. Larger lesions may also
demonstrate fluid-fluid levels. Enhancement on post-contrast imaging can
be variable from minimal to heterogeneous to more homogeneous.
Superficial hemangiomas are easy to diagnose because of the presence of
skin discoloration and MRI may only be needed to assess their extent for
surgical planning.

33. Hemangioma. MR shows a lobulated subcutaneous lesion superficial to the
hypothenar muscles, slightly hyperintense on T1w sequence, crossing compartments
and insinuating between adjacent flexor tendons (A, arrow). The lesion is very
hyperintense on T2w-FS sequence with areas of signal voids (B, arrow) and there is
also suggestion of fluid-fluid level (B, arrow). Susceptibility is seen on GRE sequence
(C, arrow). Post-contrast there is near-homogeneous enhancement (D).

35. a) Haemangioma. Coronal T1 weighted image demonstrating a lobulated mass (arrowheads) with extension into the
thumb (arrow), which is slightly hyperintense to skeletal muscle. (b) Haemangioma. Coronal short tau inversion
recovery (STIR) image demonstrating a lobulated hyperintense mass. (c) Venous malformation. Axial T2
fat-saturated image demonstrating a lobulated, serpentine lesion in the thenar eminence. (d) Venous malformation.
Coronal T1 weighted image demonstrating a mass with well-defined, low signal margin (arrowheads). (e) Venous
malformation. Coronal STIR image demonstrating a lobulated high signal mass.

36. SYNOVIAL HEMANGIOMA OF FINGER FLEXOR TENDON SHEAT. a. Sagittal T1-weigted MR image
shows an intermediate signal intensity mass. b. Sagittal proton-density- weighted MR image
discloses high hyperintensity tumor with hypointense fibrous septa. c. Sagittal T1-weigted with
fat saturation and contrast enhanced MR image reveals intense gadolinium enhancement . d.
AxialT1 and d axial T2-weigted MR images show enveloping of tendon and hypointense linear
and punctate foci simulating a GCTTS, but high signal intensity on T2 reflects pooling of blood
within vascular spaces and this is a patient with unclosed epiphyses.

37. Aneurysm/pseudoaneurysm
Aneurysms/pseudoaneurysms are rare lesions, usually secondary to trauma-
related intimal injury, or iatrogenic from arterial punctures or arteriovenous
shunts for dialysis. True aneurysms can rarely occur secondary to vasculitis. MR
features are variable depending on presence of thrombus or turbulent flow. They
are generally slightly hyperintense on T1w and T2w sequences with areas of
signal void reflecting high flow, and susceptibility artefacts may be seen on GRE
sequence if there is thrombosis. Either MR or conventional angiography can
demonstrate continuity with a parent artery, essentially excluding other
differential diagnoses. Imaging features are highly suggestive even in the
presence of a thrombus and allow avoiding catastrophic biopsies.
Arteriovenous malformations (AVMs) are high flow vascular anomalies
with abnormal connections between arteries and veins. AVMs have an
intervening central nidus, whereas arteriovenous fistulae do not. On MRI they
appear as enlarged vascular channels without a discrete soft tissue mass, which
on spin echo imaging appear as signal voids with corresponding bright signal on
flow-enhanced GE sequences. MR angiography or ultrasound can be used
to confirm the high flow state and assess arterial supply.
Skin thickening and fat deposition may be seen in
association as well as perilesional edema.

38. Aneurysm / pseudoaneurysm (partly-thrombosed). Ultrasound shows a heterogeneous
lesion with central echogenic material and peripheral turbulent arterial flow on Doppler
(A). MR shows a lobulated subcutaneous lesion slightly hyperintense on T1w sequence
(B, arrow), lying between the flexor tendons of the index and middle fingers (B,
arrowheads). It is extremely hyperintense on T2w-FS sequence with central signal void
(C, arrow), corresponding to susceptibility on GRE sequence (D, arrow). Post-contrast
there is intense serpiginous enhancement through the lesion (E, arrow).

39. (a) Small arteriovenous malformation. Coronal short tau inversion recovery (STIR) image
demonstrating a small serpiginous high signal mass on the radial aspect of the wrist
(arrow), confirmed as a vascular structure on ultrasound. (b) Axial T2 fat-saturated
image demonstrating a high signal serpiginous mass (arrow) on the radial aspect of the
wrist. There is also a ganglion (arrowhead) on the ulnar aspect of the wrist.

40. Schwannomas are the most common benign tumour of the
peripheral nerve sheath, usually occurring in the 4th to 6th
decades. On MR schwannomas are generally well
circumscribed, show low-to-intermediate signal on T1w
sequence, high signal on T2w sequence and homogeneous
contrast enhancement. It is often difficult to distinguish
schwannomas from neurofibromas, vascular lesions or even
soft tissue sarcomas. Its close relation to an expected course of
a major nerve may suggest the diagnosis. Larger tumours may
demonstrate a dural tail, “split-fat sign” (peripheral rim of
perineural fat compressed by the tumour), “fascicular sign”
(central small ring-like structures representing nerve fibers) or
“target sign” (central low signal with surrounding high signal
on T2-weighted sequence). Schwannomas can undergo cystic
or fatty degeneration. Malignant change is very rare.

41. Schwannoma. MR shows a smooth well-circumscribed nodule within the
hypothenar musculature iso-intense to adjacent muscle on T1w sequence
(A, arrow). On T2w-FS sequence the lesion shows a typical target-sign
appearance with hypointense centre with peripheral hyperintense rim (B,
arrow). Mild, near homogeneous enhancement is seen (C, arrow).

42. Schwannoma. Sagittal T1weighted image
demonstrating an ovoid intermediate signal
mass (arrowheads) on the volar aspect of the
wrist. (b) Sagittal T2 fat saturated image
demonstrating dural tail at both ends of a high
signal mass (arrows), strongly suggesting a
neurogenic lesion. (c) Schwannoma. Coronal
short tau inversion recovery (STIR) sequence
demonstrating an ovoid high signal mass in the
palm with a clearly defined dural tail (arrow).

43. Intermediate-grade lesions
Neurofibroma
Neurofibromas are common benign peripheral nerve
sheath tumours, occurring in isolation or in relation to
neurofibromatosis type 1. On MR imaging, superficial
neurofibromas tend to be asymmetric, lack fascicular
morphology and target-like signal intensity, and are likely
to involve skin, features that are evident in our case. They
are hypo- to isointense to muscle on T1w sequence and
heterogeneously hyperintense on T2w sequence.
Neurofibromas have a propensity for recurrence as
complete resection, which would require sacrificing the
whole nerve, is usually not possible.

44. Neurofibroma. MR shows a lobulated soft tissue nodule at the tip of the thumb,
isointense on muscle on T1w sequence (A, arrow), heterogeneously hyperintense on T2w-
FS sequence (B, arrow), crossing compartments to cause bony pressure erosion of the
distal phalanx (B, arrowhead). Homogeneous contrast-enhancement is seen (C, arrow).

46. (a) Neurofibroma. Coronal T1 weighted image
demonstrating an ovoid intermediate signal mass
(arrowheads). (b) Axial T2 fat saturated image
demonstrating the ‘‘target’’ sign, with a mass of
central low signal intensity (arrowheads) with
surrounding high signal. (c) Fascicular sign.
Sagittal T2 weighted image demonstrating a small
low signal ring like structure within a small
neurofibroma (arrows). Note the presence of a
dural tail (arrowhead).

47. Neurinomas. a: Schwannoma of the third finger. b: Ulnar nerve neuroma.

48. Desmoplastic fibroblastoma (collagenous fibroma)
Desmoplastic fibroblastomas are rare benign myofibroblastic tumours
arising in the subcutaneous tissue or skeletal muscle. There is a male
predominance usually around the 5th decade. On MR these are usually of
low-to-very-low signal intensity on T1w and T2w sequences and show only
minimal contrast enhancement, reflecting their collagenous nature and
low vascularity. Small intermixed areas of T2 hyperintensity may be seen
depending upon the amount of cellular components. They are only
minimally infiltrative, and the presence of calcifications and cystic changes
are unusual. One specific MR characteristic reported in the literature that
was also seen in our case is the rim enhancement of the capsule.
Collagenous fibromas are often confused with desmoid tumours on
imaging. However, desmoid tumours are often painful and more
infiltrative at presentation. Moreover, desmoid tumours show prominent
areas of high signal on T2w sequence and internal enhancement because
of their cellular nature. Preoperative differentiation is important to avoid
overtreatment and unnecessary extensive procedures performed for
desmoid tumours. Other differential diagnoses include FTS, calcifying
fibrous tumours, leiomyoma and GCTTS.

49. Desmoplastic fibroblastoma. MR shows an lobulated mass within the first dorsal interossei
muscle of heterogeneously low signal on both T1w (A) and T2w-FS sequences (B), with loss
of surrounding fat planes. There is heterogeneous enhancement (C, arrow), and the lesion
is seen to cross compartments to abut the index finger extensor tendon (C).

50. Desmoplastic fibroma of tendon sheath.

51. Giant cell tumour of tendon sheath
GCTTSs are common tumours, usually presenting as painless masses
at 30–50 years, with a slight female predilection. They are typically
found in the hands or feet associated with degenerative joints and
thought to be reactive lesions to adjacent inflammation rather than
true neoplasms. GCTTSs are histologically benign but pressure
changes in adjacent bone can be seen on plain radiographs in 10-
20 % of cases. MR shows a lesion in close relation to joints and
tendons, predominantly of low signal on T1w sequence and of
intermediate to slightly high signal on T2w sequence. Susceptibility
artefacts on GRE sequence are typical because of hemosiderin
deposition and this is a helpful feature. Strong enhancement is seen
because of the presence of numerous proliferative capillaries in the
collagenous stroma. Differential diagnoses include focal nodular
synovitis, which also contains hemosiderin while a more
heterogeneous signal and enhancement can result in confusion with
soft tissue sarcomas.

52. Giant cell tumour of tendon sheath. Plain radiographs show well-defined lucency at the head
of the first metacarpal (A). MR shows a lobulated subcutaneous lesion of intermediate T1w
signal (B), crossing compartments to cause bony pressure erosion at the first
metacarpophalangeal joint. It is inseparable from the flexor pollicis longus tendon (B, orange
arrow) and of heterogeneous intermediate-to-high signal on T2w-FS sequence (C). Areas of
susceptibility on the GRE sequence (D). There is near homogeneous avid enhancement (E).

53. Giant cell tumor of flexor tendon sheath in a 45 year-old-man who presented with a non tender
lump for 1 year. MR images reveal a lobulated soft tissue lesion wrapping the flexor tendon. It
is of intermediate signal intensity on T1W image (a). It is iso to slightly hyperintense on T2W
fat saturated image (b), demonstrates small foci of susceptibility on gradient image (c) (red
arrow) and shows avid, heterogenous enhancement on post contrast image (d).

54. Giant Cell Tumor of the sheath of flexor carpi radialis: post-
contrast study at different planes. Homogeneous uptake.

55. Glomus tumours are benign disordered proliferation of the
neuromyoarterial apparatus that serves to regulate skin circulation.
They usually occur in the 4th to 5th decade and are three times
more frequent in females. Patients with glomus tumour seek
medical attention early, but the mass is frequently too small to be
identified on physical examination. The classic triad of moderate
pain, temperature sensitivity and point tenderness is inconsistently
present. Useful distinguishing features on MR are its characteristic
location, pressure erosion of underlying bone, very high and
homogeneous signal on T2w sequence, low signal on T1w sequence
and intense enhancement. Although these MR signal characteristics
can be associated with any vascular tumour, the typical subungual
location and its small size should lead one to suspect glomus
tumour in most cases. In particular, T2w-FS and post-contrast
sequences are very helpful in delineating small tumours. The lesion
is typically painful, and surgery is the treatment of choice for
symptom relief and histological confirmation.

56. Glomus tumour. Plain radiograph shows well-defined scalloping along the ulnar aspect of
the left ring finger distal phalanx (A, arrow). MR revealed a smooth, well-circumscribed
subcutaneous lesion crossing compartments to cause bony pressure erosion at the tip of
the finger. It is of intermediate signal on T1w sequence (B, arrow), extremely and
homogeneously hyperintense on T2w-FS sequence (C, arrow). Homogeneous enhancement
is seen (D, arrow).

58. Malignant lesions
Undifferentiated pleomorphic sarcoma
Previously known as malignant fibrous histiocytoma, this is the most
common soft tissue sarcoma in adults with a wide age range of
30–80 years old and a slight male predilection. It is thought to arise
from undifferentiated mesenchymal stem cells and usually occurs in
the soft tissues of the retroperitoneum and proximal extremities.
Occurrence in the hand is rare. MR is the imaging modality of choice
to stage and characterize the tumour. It is typically intermediate to
low signal on T1w sequence and heterogeneously high signal on
T2w sequence; however, appearance may vary depending on the
presence of calcification, fibrous tissue, hemorrhage or necrosis. The
tumour is fairly well defined despite its malignant nature because of
a pseudocapsule, but may exert a mass effect or encase
neurovascular bundles. Other less common subtypes of pleomorphic
sarcoma have been identified based on the proportion of myxoid,
fibrous or cellular components.

59. Undifferentiated pleomorphic sarcoma. MR shows an irregular mass,
hypointense on T1w sequence infiltrating hypothenar musculature crossing
compartments to involve flexor tendons of the little and ring finger (A,
arrowhead) and overlying skin (A, arrow). It is heterogeneously hyperintense on
T2w-FS sequence (B, arrow). There is heterogeneous enhancement (C, arrow).

60. Synovial Sarcoma of Wrist Area.

61. Primary squamous cell carcinoma of the skin
Primary squamous cell carcinoma (SCC) of the skin
usually occurs in the older age group commonly over
the sun-exposed back of hands. Diagnosis is usually
suspected clinically and easily confirmed on bed-side
punch biopsy. Imaging is utilized for local staging. On
MR, the tumour has an infiltrative appearance and
can be diffuse or focal. It is usually of low to
intermediate signal on T1w sequence and
heterogeneously hyperintense on T2w sequence with
variable enhancement. Its epicenter in the cutaneous
layer, irregular and infiltrative appearance should
raise suspicion for a primary skin malignancy.

62. Squamous cell carcinoma. MR shows infiltrative circumferential skin and
subcutaneous soft tissue thickening around the thumb metacarpophalangeal joint
of low signal on T1w sequence (A, orange arrows). There is involvement of
extensor pollicis brevis and abductor pollicis brevis (C, blue arrows) with erosion of
underlying bone. The lesion is intermediate heterogeneously hyperintense on
T2w-FS sequence (B), with heterogeneous contrast enhancement (C).

63. SCC in an 84-year-old female presenting with diffuse circumferential swelling over
the base of the right thumb associated with ulcerations. (a) T1w sequence shows
infiltrative circumferential skin and subcutaneous soft tissue thickening around the
thumb metacarpophalangeal joint of intermediate signal. There is involvement of
the extensor pollicis brevis and abductor pollicis brevis (arrow) with erosion of
underlying bone. (b) The lesion is heterogeneously hyperintense on T2w-FS
sequence. (c) There is also heterogeneous diffuse, circumferential enhancement.

64. Malignant bony lesions
Osseous metastases to the hand (acrometastases) is uncommon. The
most common primary sites of malignancies are the lung, kidney and
breast, and they usually indicate poor prognosis. Plain radiographs
showing expansile destructive lytic lesions are usually diagnostic in the
appropriate setting. MR can be useful if there is any uncertainty about
the clinical history or unusual radiographic appearance. Treatment is
palliative but can improve quality of life.
Chondrosarcoma is the most common primary bone malignancy in
adults and may occur as a malignant degeneration of a benign
chondroid lesion such as an enchondroma. Plain radiograph shows a
typical “ring-and-arc” matrix with endosteal scalloping and cortical
thinning, but in higher grade subtypes there is often bony destruction
and irregular margins. MR is usually used to for local staging.
Differential diagnosis for a lesion in the distal phalanx is a glomus
tumour, but the plain radiograph showing a primarily expansile bony
lesion effectively excludes it.

65. Metastasis. Plain radiograph shows permeative destruction of the fifth metacarpal
(A). MR shows destruction of the fifth metacarpal with infiltrative soft tissue,
predominantly of intermediate signal on T1w sequence (B), heterogeneously
hyperintense on T2w-FS sequence (C). Heterogeneous enhancement is seen (D).

66. Low grade fibrosarcoma of tendon sheath. MRI reveals a relatively well circumscribed ovoid mass
in the ulnar aspect of the right distal forearm, located primarily in the subcutaneous plane. It lies
in close proximity to the flexor carpi ulnaris tendon (blue arrow), with no clear fat plane seen
between the two. This lesion is predominantly of low signal intensity on (a) T1W and (b) T2W
images with heterogenous area of bright T2 signal (orange arrow). (c) On T1 fat saturated post
contrast image, the lesion appears very vascular and shows mildly heterogeneous enhancement.
Dark linear strands are also seen on T1, T2W and post contrast images which suggest fibrous
nature of the lesion. (d) On ultrasound which is inadequate for tissue characterization, the lesion
appears isoechoic. The flexor carpi ulnaris tendon lies deep to it (arrow).

67. Fibrosarcoma of the tendon sheath
Fibrosarcoma is a rare malignancy of mesenchymal origin composed
of fibroblasts and collageneous matrix. The primary adult form is
slightly more common in males in the 35–55-year age group. They
usually arise from the joint capsule or bones around the knee and
pelvis, less commonly from soft tissue such as muscle or the tendon
sheath. Secondary forms occur in a setting of prior irradiation or other
malignant transformation from benign bony disorders such as Paget’s
disease. On MR, the lesion is usually of low signal on both T1w and
T2w sequences reflecting a fibrous matrix but may be interspersed
with high-signal areas on T2w sequence from increased cellularity or
necrosis. Post-contrast there is usually intense enhancement, and a
“spoke-wheel” pattern of enhancement has been described. Necrosis
and hemorrhage commonly seen in high-grade fibrosarcomas is
uncommon in the low-grade variety. Differentiating low-grade
fibrosarcomas from fibromatosis and its variants may be difficult.
Histological analysis is required for the definite diagnosis.

68. Fibrosarcoma of the tendon sheath in a 47-year-old female presenting with focal swelling
along the ulna aspect of the right wrist, gradually increasing in size over a few months. (a)
Ultrasound shows a well-defined hypoechoic lesion along the ulnar side of the wrist
abutting the extensor carpi ulnaris (arrow). (b) T1w sequence shows a hypointense well-
circumscribed subcutaneous lesion abutting the extensor carpi ulnaris (arrow). (c) The lesion
is predominantly of low signal on T2w sequence, with small areas of high signal (arrow)
indicating a more cellular/necrotic component. (d) Heterogeneous enhancement is seen

69. SYNOVIAL SARCOMA OF HAND. Up- oblique sagittal T1-weighted images without and with
contrast enhancement exhibit a mass which has a "cluster of grapes" appearance. Down.
axial T2- weighted MR image of the same patient shows signal heterogeneity.

72. Mimickers of soft tissue tumours in the hand and wrist are
more frequent than true neoplastic lesions. Pseudotumors belong to
a large and heterogeneous group of disorders, varying from normal
anatomical variants, cystic lesions, post-traumatic lesions, skin
lesions, inflammatory and infectious lesions, non-neoplastic vascular
lesions, metabolic disorders (crystal deposition disease and
amyloidosis) and miscellaneous disorders. Although the imaging
approach to pseudotumoral lesions is often very similar to the
approach to “true” soft tissue tumoral counterparts, further
management of these lesions is different. Biopsy should be
performed only in doubtful cases, when the diagnosis is unclear.
Therefore, the radiologist plays a pivotal role in the diagnosis of
these lesions. Awareness of the normal anatomy and existence and
common imaging presentation of these diseases, in combination
with relevant clinical findings (clinical history, age, location and skin
changes), enables the radiologist to make the correct diagnosis in
most cases, thereby limiting the need for invasive procedures.

73. Inflammatory pseudotumor
Inflammatory pseudotumors are thought to be an
abnormal inflammatory response to trauma or an
infectious agent. They occur over a wide age range with
equal male to female distribution. Usually seen in the
orbits, head and neck, lung and various sites in the
abdomen, their occurrence in the hand is rare. MR features
are non-specific, usually those of a well-circumscribed
lesion of low signal on T1w sequence and variable signal on
T2w sequence with variable enhancement. Although this
lesion is considered benign, recurrence and malignant
change have been reported and complete surgical resection
is required. Histologically, this entity encompasses a
spectrum from early inflammatory lesions to chronic
calcifying/sclerotic ones

74. Benign inflammatory fibrosclerotic lesion (pseudotumor). (a) T1 axial image shows an
intermediate signal intensity lesion overlying the 4th metacarpal. (b) On T2 (F/S) axial image
the lesion reveals hypo to intermediate signal intensity. The lesion is closely related to the
palmar interosseous muscle of fourth web space but remains separated from the flexor
tendon sheath by clear fat plane. (c) On colour Doppler ultrasound study, the lesion appears
iso to hypoechoic and demonstrates vascularity. The flexor tendon is seen deep to it.

75. Soft tissue swelling around the pisotriquetral joint and widening of the pisotriquetral
joint. (B) T2-weighted coronal magnetic resonance imaging (MRI) of the pisotriquetral
joint. (C) Juxta-articular axial MRI of the pisiform demonstrating an intraarticular
lobulated homogeneous material with surrounding high signal soft tissue.

76. Gouty tophi can present as focal masses. Plain radiographs usually suggest the
diagnosis. Juxta-articular erosions with overhanging edges and associated calcified
soft tissue masses are typical findings. MR findings of gouty tophi are also rather
characteristic. The lesions are of low to intermediate signal on all MR sequences
mainly because of the presence of calcification and can show peripheral enhancement.
Gouty tophus. Plain radiograph shows amorphous calcification adjacent to the ulna styloid (A, arrow). MR shows an
irregular, subcutaneous lobulated mass of low signal on STIR (B, arrow) and T2w-FS sequences (C, arrow). Mild
peripheral enhancement is seen (D, arrow). Erosions of the underlying bone are also seen (D, arrowhead).

77. a Clinical picture of tophaceous gout. Peri-articular soft-tissue swelling best seen at the proximal interphalangeal joint of the
third finger. b Corresponding plain radiograph showing soft-tissue swelling and adjacent periosteal new bone formation
(arrow). c Ultrasound of another patient with tophaceous gout at the metacarpophalangeal joint of the thumb, showing a
hypoechoic mass with intralesional reflections with retro-acoustic shadowing due to monosodium urate crystal deposition
(arrows). D, Pseudogout (hydroxyapatite deposition disease) in another patient. Plain radiograph showing linear and
amorphous calcifications at the joint capsule of the distal interphalangeal joint of the index (arrows)

78. Bizarre parosteal osteochondromatosis proliferation (Nora’s lesion)
Bizarre parosteal osteochondromatosis proliferation (BPOP), or Nora’s lesion, was first described
by Nora in 1983. The lesion is regarded as a reactive mass of heterotopic mineralization arising
from the periosteal aspect of an intact cortex, without medullary changes.
Bizarre parosteal osteochondromatous proliferation (Nora’s lesion). a Plain radiograph of the
finger showing a turret exostosis at the dorsal aspect of the proximal phalanx of the second
finger (arrowhead). b Longitudinal ultrasound shows the exostosis causing focal contour
deformity of the cortical bone (arrowheads) with adjacent hypoechoic cartilage cap (calipers).

79. Tenosynovitis refers to inflammation of the tendon and tendon sheath. Localized
inflammation can appear mass-like clinically. MRI findings of tenosynovitis include
increased fluid signal within the tendon sheath, tendon sheath distension, synovial
proliferation and enhancement. According to one study, flexor tenosynovitis of the hand
diagnosed by MRI is a strong predictor of early rheumatoid arthritis.
Tenosynovitis. T1w (A, arrow) and STIR sequences (B, arrow) show thickening and edema of
the index finger flexor tendon sheath. Diffuse enhancement of the sheath is seen (C, arrow).

80. Inflammatory tenosynovitis in a patient with known rheumatoid arthritis. a Transverse ultrasound
of the extensor tendons of the wrist showing fluid surrounding the extensor tendons 4. b Transverse
power Doppler examination shows increased vascularity within the tendon sheath and tendons

81. Extensor carpi ulnaris tenosynovitis. Axial FS T2-WI shows fragmentation
into multiple tendon fragments of the extensor carpi ulnaris tendon
(arrowheads). Note increased fluid and debris within the tendon sheath.

82. Chronic calcific tendinopathy in a patient presenting with 10-year history of focal swelling
along the volar aspect of the left middle finger.(a) Plain radiograph shows well-defined
scalloping along the volar aspect of the middle finger proximal phalanx with an overlying
striated pattern of calcification (arrow). (b) T1w sequence shows focal swelling of the flexor
digitorum longus tendon (arrow) causing scalloping of the underlying bone. No discrete
mass is seen. (c) There is a mild increase in signal in the tendon on T2-FS sequence
suggesting tendinosis. There is bony scalloping but no significant marrow edema, suggesting
a chronic process. (d) Diffuse thickening and intense enhancement of the tendon sheath is
seen, reflecting an element of active tenosynovitis (arrow)

83. Erosive arthropathy. Plain radiograph shows narrowing and sclerosis at the radiocarpal
joint, osteophytes, loose bodies (A, arrow). T1w (B) and T2w-FS (C) MR sequences (C)
show synovial thickening, subchondral erosions along the carpal bones and small
effusion at the distal radio-ulna joint. Marked synovial enhancement is seen (D, arrow).

84. Rheumatoid arthritis. a Coronal SE T1-WI. Hypointense subcutaneous nodule at the palmar aspect of the distal phalanx
of the right digit 3 (arrowheads). b Sagittal FS TSE T2-WI. High signal intensity of the lesion (black arrows). There is
moderate pressure erosion of the palmar aspect of the distal phalanx. c Sagittal FS SE T1-WI after intravenous injection
of gadolinium contrast medium. There is peripheral enhancement of the lesion (black arrowheads).
Rheumatoid nodule
Rheumatoid nodules may be rarely observed in cases of long-standing rheumatoid arthritis or other
rheumatic disease such as lupus, Spondyloarthropathy, agammaglobulinaemia and rheumatic fever.

85. Non-neoplastic vascular lesions
Hypothenar hammer syndrome
A post-traumatic partially thrombosed palmar aneurysm resulting from repeated
trauma to the wrist (hypothenar hammer syndrome) may mimic a soft tissue tumour
Hypothenar hammer syndrome. a Sagittal SE T1-WI shows a hypointense lesion superficial to the flexor tendons (arrowhead) and
immediately distal to the hamulus of the hamate (asterisk). b Axial FS SE T1-WI after intravenous administration of gadolinium
contrast medium shows focal aneurysmal dilatation of the ulnar artery with central thrombosis (arrow). Note only faint peripheral
enhancement. c Doppler ultrasound shows intraluminal thrombosis of the aneurysm of the ulnar artery. d MR angiography shows
multiple stenosis at the distal ulnar artery with aneurysmal dilatation with internal clot formation (arrow)

86. Palmar fibromatosis. a Longitudinal Doppler ultrasound. Hypoechoic nodule adjacent to the flexor tendon of the palm of the
hand (third ray). b Axial SE T1-WI in another patient shows a hypointense lesion at the palmar aspect of the thumb (arrow). c
Axial FS SE T1-WI after intravenous administration of gadolinium contrast medium shows diffuse enhancement (arrow)
Palmar fibromatosis (Dupuytren’s disease)
Palmar fibromatosis was originally described in 1831 by the French physician Dupuytren's and is often
referred to as Dupuytren’s disease or contracture. The etiology of palmar fibromatosis is still a matter of
debate, but it is thought to represent a benign fibroblastic tumour rather than a pseudotumor. Other
etiological factors include trauma, microvascular injury, immunological processes and hereditary factors.

87. a) Periosteal Chondroma. Lateral plain radiograph of the ring finger showing a
soft tissue mass with scalloping of the underlying bone (arrowheads) and an arc
of peripheral calcification (arrow). (b) Sagittal T1 weighted image showing an
intermediate signal mass (arrowheads). The underlying bone is scalloped .

88. Anomalous muscles
Anatomic variants of the muscles of the wrist and hand are common. These can be
clinically significant when they cause compressive symptoms or appear mass-like.
Often lesions are not recognized on imaging as the signal characteristics are identical
to normal muscle. The accessory abductor digiti minimi muscle is present in up to 24%
of all wrists. On axial images, a fusiform mass is present with the signal characteristics
of muscle lateral and anterior to the pisiform bone at the level of the origin of the
abductor digiti minimi muscle. This may cause an ulnar or median neuropathy. The
extensor digitorum brevis manus muscle occurs in 1–3% of the population. Clinically
this may be mistaken for a dorsal ganglion. This arises from the distal radius and
inserts on the index finger. Normally the extensor tendons are unaccompanied by their
muscle bellies at the level of the carpus. However, in the presence of an extensor
digitorum brevis manus muscle, it is noted that there is a muscle medial to the tendon
of the index finger at or distal to the level of the carpus. Palmaris longus muscle
variants may compress the ulnar and median nerves. The normal muscle arises from
the medial epicondyle and inserts into the palmar aponeurosis. MRI may demonstrate
a midline mass superficial to the flexor retinaculum at the wrist, but diagnosis may
require more proximal imaging of the forearm. Proximal origin of the lumbrical
muscles occurs when the origin of these muscles is within the carpal tunnel rather
than just distal to it (diagnosed with the fingers in extension) and is seen in up to 22%
of individuals. It may be the cause of carpal tunnel syndrome.

90. Accessory palmaris longus muscle. Sagittal T1 weighted image
demonstrating an accessory muscle belly at the level of the wrist (arrows).

91. A fat-suppressed T1-weighted post-contrast coronal image of the hand at the level of the carpal tunnel in a 58-
year-old woman with horseshoe abscess due to tuberculosis. Note involvement of the FPL (short arrow) and
FD5 (long arrow) tendon sheaths. The digital flexor sheaths of FD2, FD3, and FD4 are spared (arrowheads).

92. A fat-suppressed proton density axial image just proximal to the carpal tunnel
demonstrates increased tenosynovial fluid (short arrows) and synovial
proliferation (arrowheads) in the radial and ulnar bursae as well as multiple
extensor tendon sheaths in this 45-year-old female with rheumatoid arthritis.

93. Sarcoidosis is characterized by non caseating granulomata. The musculoskeletal
system is involved in approximately 1-13% of patients with this disease. MRI
findings in sarcoidosis include tenosynovitis, tendinosis, bursitis, and rice bodies.
Often, a synovial or soft tissue biopsy is necessary to confirm the diagnosis.
A T2-weighted coronal image proximal to the
carpal tunnel demonstrates numerous T2
hypointense foci, consistent with rice bodies within
a markedly distended ulnar bursa (arrowheads).
A fat-suppressed T1-weighted axial image of the wrist
proximal to the carpal tunnel demonstrates
heterogeneous T1 signal intensity surrounding the flexor
tendons.
A T2-weighted axial image of the wrist proximal
to the carpal tunnel demonstrates rice body
formation within a large amount of fluid in the
radial and ulnar bursae (arrows). The rice bodies
are not evident on the T1-weighted axial view.

94. PVNS and GCT are histologically identical benign
synovial proliferative diseases. They can be categorized
into four clinicopathologic subtypes based on morphology
(focal or diffuse) and location (intra-articular or extra-
articular). The familiar giant cell tumor of the tendon
sheath is the focal, extra-articular form of the disease,
most often presenting as a nodular mass along the volar
aspects of the fingers. Simple excision is usually curative.
The diffuse, extra-articular form of the disease is less
common and much more aggressive, widely infiltrating
soft tissues and frequently recurring following excision.
On MRI, diffuse-type GCT (also termed extra-articular
PVNS) appears similar to conventional (intra-articular)
PVNS (22a-22d) with lobulated margins, hemosiderin
deposition, and contrast enhancement.

95. Diffuse-type GCT (PVNS). T1-weighted sagittal (22a), fat-
suppressed T1-weighted post-contrast sagittal (22a), T1-
weighted coronal (22c), and fat-suppressed T1-weighted
post-contrast axial (22d) images demonstrate the hourglass
configuration of infiltrative, enhancing soft tissue within the
palmar bursae. Scattered foci of low signal intensity are
compatible with hemosiderin (arrows).

96. Post-traumatic lesions
Myositis ossificans (MO) is a benign condition of heterotopic bone formation,
which can mimic soft-tissue malignancies. It is rarely seen in the hand region. A
history of trauma is present in about 60% of cases. In the acute stage, the most
frequent complaint is pain, tenderness and soft tissue swelling.
Myositis ossificans of the thenar in a 7-year-old boy presenting
with pain and swelling at the thumb (active phase). a Plain
radiograph. Note calcifications (arrow) in the thenar. b Axial
SE T2-WI shows an ill-defined intramuscular mass that is
hyperintense with central areas of low signal. Additionally,
there is an intralesional area of heterogeneous low signal,
corresponding to the calcifications on plain films (arrow).

97. Foreign-body granuloma:
Foreign-body granuloma is usually observed after previous penetrating trauma, in which the foreign
body is not properly retrieved. Most patients will present with a palpable mass, pain and discomfort
Foreign body (wood) crossing the metacarpal heads. a Ultrasound shows a central hyperechoic wood fragment
surrounded by a hypoechoic inflammatory reaction. b On power Doppler examination, there is increased vascularity at
the periphery of the lesion. c Coronal FS T2-WI, showing a hypointense wooden splinter (arrows), with surrounding high
signal band, due to inflammatory reaction. d Axial FS T1-WI after intravenous administration of gadolinium contrast
medium showing a rim-enhancing abscess (white arrows) adjacent to the wooden splinter (black arrowhead).

98. Anomalous osseous structures
Accessory osseous structures such as a carpal boss may sometimes simulate soft tissue masses clinically. A carpal
boss consists of a firm osseous prominence on the dorsum of the hand at the base of the second or third
metacarpal and adjacent to the capitate and trapezoid bone. On MRI, there may be reactive bone marrow edema
and associated joint effusion at the carpo-metacarpal joint. Frictional bursitis may occur adjacent to carpal boss.
Carpal boss. a Plain radiograph (lateral view) showing a bony prominence at the dorsal aspect of the
carpometacarpal joint (arrow). b Sagittal fat-suppressed (FS) TSE T2-weighted image (WI). Note bone
marrow edema and subchondral cyst formation at the carpo-metacarpal joint (arrows).

99. 86-year-old male with diabetes presented with progressively worsening tender swelling over
the right hand. (A) Axial T2w-FS image shows a large fluid collection at the dorsal aspect of
the rim with (B) peripheral enhancement. Appearance is consistent with an abscess.

100. Thank You.