Soft tissue tumors are a heterogeneous group of lesions that arise from nonepithelial, extraskeletal tissues including adipose tissue, muscles, tendons, blood vessels and lymphatics. Imaging plays an important role in evaluating these tumors. There are nine major groups of soft tissue tumors including adipocytic tumors, vascular tumors, fibroblastic tumors, fibrohistiocytic tumors, smooth muscle tumors, skeletal muscle tumors, pericytic tumors, chondro-osseous tumors and tumors of uncertain differentiation. Lipoma is the most common benign adipocytic tumor while liposarcoma is a malignant adipocytic tumor. Hemangioma is a common benign vascular tumor and angiosarcoma is the most common

1. SOFT TISSUE TUMORS

2. Soft Tissue Tumors
• Soft tissue tumors are a heterogeneous group of lesions which
arise from different nonepithelial, extraskeletal elements, which
include adipose tissue, smooth and skeletal muscle, tendon,
cartilage, fibrous tissue, blood vessels, and lymphatic
structures.

3. IMAGING MODALITIES
• Plain radiography
• Ultrasonography (USG)
• Magnetic resonance imaging (MRI)
• Computed tomography (CT)
• Positron emission tomography-computed
tomography (PET-CT)

4. Criteria for differentiating benign and malignant
soft tissue tumors
• Location
• Signal intensity
• Signal homogeneity
• Size (growth rate)
• Tumor margin
• Compartment spread
• Neurovascular invasion
• Adjacent soft tissues
• Bone infiltration/destruction

5. Nine major groups of tumors
• Adipocytic tumors,
• Vascular tumors,
• Fibroblastic/Myofibroblastic tumors,
• Fibrohistiocytic tumors,
• Smooth muscle tumors,
• Skeletal muscle tumors,
• Pericytic (perivascular) tumors,
• Chondro-osseous tumors and
• Tumors of uncertain differentiation.

6. Adipocytic Tumors
Lipoma :
• most common benign soft tissue tumor
Radiograph - may be unremarkable or demonstrate a mass of fat density.
CT - Tumor is well-defined and homogeneous without enhancement following administration of
intravenous contrast.
MR imaging - The signal intensity of lesion parallels that of subcutaneous fat on all pulse
sequences being hyperintense on both T1 and T2-weighted images.
• Cartilage and bone formation considered as metaplastic may be occasionally seen in a
lipoma, particularly if it is long standing – lipoblastoma/hibernoma/lipomatosis .
• Diffuse lipomatosis is characterized by diffuse overgrowth of mature adipose tissue infiltrating
through the soft tissue of the affected extremity or the abdomen .
Liposarcoma :
• Well-differentiated, dedifferentiated, myxoid, pleomorphic and mixed .
• MR imaging features that suggest a diagnosis of well-differentiated liposarcoma vs lipoma
include prominent internal septae more than 2 mm in thickness and nodular nonadipose
areas.

7. Lipoma — A fat density mass seen in
medial part of right thigh suggestive of
lipoma on plain radiograph
Lipoma: Axial CECT image showing well
defined,homogeneous, fat attenuation
lesion in the subcutaneous plane of
left side of the neck

8. Liposarcoma (well-differentiated): Axial CECT and coronal showing a well-
defined fat attenuation lesion with prominent internal septae located in the
pelvis, inguinal region and upper thigh

9. Vascular Lesions
Hemangiomas .
Vascular malformations .
Hemangioma
• Common sites of hemangiomas include face and neck(60%), trunk (25%)
and extremities (15%).
• Clinical findings : strawberry-like appearance in cutaneous lesions
• Ultrasonography is often sufficient for diagnosis, MR may be required to
demonstrate extent for presurgical planning or for treatment response
evaluation.
• Ultrasonography typically reveals a complex mass with anechoic channels
with phleboliths and acoustic shadowing
• Noncontrast CT generally shows a poorly defined lesion with attenuation
similar to that of skeletal muscle with significant enhancement on the
contrast administration , + phleboliths .
• MRI : T1 - poorly marginated mass of low to intermediate signal intensity T2
–well marginated mass with very high-signal intensity in areas of vascular
components .

10. A) Hemangioma: Plain radiograph showing soft tissue mass with phleboliths
between first and second metacarpals, (B) Ultrasonography of the mass
shows an isoechoic solid lesion with acoustic shadowing from phleboliths

11. CT scan (A) showing hemangioma involving the soft tissues superficial to the
body and ramus of the mandible on right side. The mass shows multiple
serpiginous channels, (B) Selective right common carotid, digital subtraction
angiography shows features suggestive of hemangioma with vascular supply
from right lingual artery

12. Kaposiform hemangioendothelioma:
• Kaposiform hemangioendothelioma is a vascular neoplasm of
infancy that may display an infiltrative growth pattern.
• presents in the first year of life
• common site – extremities , Head and neck .
• may be associated with Kasabach-Merritt phenomenon (a
coagulopathy with profound thrombocytopenia).
• On MR imaging these lesions ill-defined margins involvement
of multiple tissue planes, cutaneous thickening and stranding
of the subcutaneous fat, and destructive changes or
remodeling of adjacent bones.

13. Lateral radiograph shows increased soft
tissue density and bulk in keeping with
extensive limb overgrowth.
T1 weighted imaging reveals
characteristic, ill-defined hypointense soft
tissue thickening involving multiple
planes. T2 typically demonstrates
hyperintense masses with reticular
stranding in the subcutaneous fat.
Kaposiform hemangioendothelioma

14. Soft Tissue Angiosarcoma
Malignant vascular tumor occurring at any age, with peak
in the 7th decade
Has high incidence of local recurrence and distant
metastasis
Predisposing risk factors
• Chronic lymph edema, previous radiotherapy, foreign
bodies, immune suppression and familial syndromes such
as type 1 neurofibromatosis, Klippel-Trénaunay-Weber
syndrome, and Maffucci syndrome.

15. Vascular Malformations
• High-flow Vascular Malformations
- Arteriovenous Malformations (AVMs)
- Arteriovenous fistula (AVF)
• Low-flow Vascular Malformations
- Venous malformations
- Lymphatic malformations

16. Arteriovenous Malformations (AVMs)
clinical presentation :
• pulsatile mass with palpable thrill and localized warmth .
complications
• hemorrhage, ischemia from arterial steal, asymmetric overgrowth or even high-
output cardiac failure .
Magnetic resonance imaging :
• Enlarged feeding arteries and draining veins, which appear as tortuous channels
and flow on spin-echo images and highsignal intensity channels on gradient
echo images, without a well-defined mass
CT/MR angiography :
• demonstrate the vascular supply which aids in planning
subsequent interventions

17. High flow AVM: CT angiography of a 22-year-old male presenting with gum
bleed showing a large nidus involving the right masseter and infratemporal
fossa with rapid venous filling

18. Arteriovenous fistula (AVF)
• Arteriovenous fistula comprises of usually a single
large vascular channel between an artery and a
vein, with no intervening nidus. It may be
congenital, or develop following a penetrating
trauma

19. Venous malformations
• most common form of all vascular malformations, often misnamed as
cavernous hemangiomas .
• present at birth as soft, fluctuant
masses with overlying skin discoloration
• On USG and MR imaging, venous malformations appear
either as dilated veins or more often lobulated multilocular masses. These
locules represent venous lakes separated from each other by interstitial
septa .
• Phleboliths may be seen within, with Doppler evaluation revealing venous
flow pattern.

20. • The T2-weighted sagittal image shows a lesion of increased signal intensity in the
soleus muscle. The lesion is composed of high signal intensity tubules (red
arrows). An area of venous communication is seen along the cephalad portion of
the lesion (blue arrow). (2b) The proton density-weighted sagittal image
demonstrates fluid-fluid levels within the tubules of the lesion (arrowheads).
Areas of fatty atrophy are seen along the periphery of the lesion (blue arrows).

21. Lymphatic malformations
• common term used for these lesions is lymphangioma or cystic hygroma
• Slow flow, cystic malformations
• size of the cysts varies from few millimeters (microcystic) to larger variable sized (in centimeters)
cystic spaces (macrocystic variant or cystic
hygroma)
Cystic lymphangioma (hygroma)
most common type and are usually located in the neck or axilla .
unilocular or multilocular spaces containing serous or chylous proteinaceous material.
Sonography - shows a multiloculated cystic mass with septae of variable thickness. Cystic
lesions complicated by hemorrhage or infection may appear solid
lymphangioma - unilocular or multilocular cystic mass
MRI - typical appearance is heterogeneous with a lowsignal intensity, similar to or slightly less
than that of muscle on T1-weighted images and high-signal intensity greater than that of
fat on T2-weighted images, reflecting the preponderance of fluid-filled cystic spaces

22. Lymphangioma USG (A) and CECT (B) of a 2-month-old infant showing a large
cystic mass with few septae on left side of neck

23. Fibroblastic/Myofibroblastic Tumors
 group of mesenchymal tumors
Four types :
• benign fibrous proliferations,
• fibromatoses,
• fibrosarcomas, and
• fibrous proliferations of infancy and childhood.
Benign lesions
nodular fascitis, fibromatosis colli, myofibroma, giant cell angiofibroma
Myositis ossificans is also now classified under benign
fibrous proliferations

24. Fibromatosis
• soft tissue lesions characterized by intermediate malignant
potential
• locally infiltrative and tend to recur
superficial or deep
Superficial - palmar, plantar and penile fibromatosis
Deep - extra-abdominal, abdominal, intra-abdominal
and extremity fibromatosis

25. Fibromatosis
Radiographs
• nonspecific but may reveal a mass
• Bone involvement may be seen in the form of a pressure erosion, scalloping without invasion or
destruction, or stimulation of periosteum producing a “frond-like” periosteal reaction
CT
• nonspecific soft tissue mass
MRI
• heterogeneous signal intensity approximately similar to fat on T2-weighted and muscle on T1-
weighted images
• Moderate to marked enhancement following the administration of intravenous Gd-DTPA.

26. Fibromatosis
Fibromatosis: CECT of a 24-year-
old female showing a large,
heterogeneous left pelvic mass

27. T1W and STIR coronal scans of a patient of fibromatosis showing large
lobulated mass located over the left infraclavicular region. The mass is
isointense on T1W (A) and hyperintense on STIR (B) sequences
Fibromatosis

28. • Solitary fibrous tumor, hemangiopericytoma and
inflammatory pseudotumor are also classified as
intermediate lesions, while fibrosarcoma is the malignant
tumor.
Inflammatory myofibroblastic tumor (inflammatory pseudotumor )
 commonly occurs in the orbit
other sites - lung, trachea, skull base and thyroid
 associated with fibrosing mediastinitis and retroperitoneal fibrosis

29. Pseudotumour of the right lateral rectus
muscle. Note the involvement of the
tendinous insertion.

30. Fibrohistiocytic Tumors
Benign Forms
• Pigmented villonodular synovitis (PVNS)
• Giant cell tumor of the tendon sheath (GCTTS)
Intermediate forms
• Dermatofibrosarcoma Protuberans
Malignant form
• Malignant Fibrous Histiocytoma

31. pigmented villonodular synovitis (PVNS)
A well defined nodular lesion is seen
within knee joint appearing
heterogenously hypointense on T1W and
T2W images. It is seen to indent Hoffa's
fat pad, and seen close to tibial
attachment of ACL
DD : Synovial chondromatosis

32. Giant cell tumor of the
tendon sheath (GCTTS)
A well defined oval shape mass is seen
anterior to the talus, extra articular in
position and underneath the tendon of
the Extensor hallucis longus.The mass
displays low signal on T1, lower signal on
T2 likely from hemosiderine deposition,
heterogeneous high signal on STIR and
avid enhancement on post contrast study
with two foci of calcification seen within.
No evidence of infiltration of the adjacent
structures.

33. Dermatofibrosarcoma Protuberans
• Rare tumor seen in middle-age adults .
• Commonly found on the trunk or proximal extremities
• Arises from dermis but it spreads locally into the deeper tissues.
Clinical presentation
 slow-growing subcutaneous plaque or nodule with overlying skin discoloration
simulating a vascular lesion .
MR - Iso- to Hypointense to muscle on T1W images, hyperintense on T2W images
with uniform or patchy enhancement

34. Malignant Fibrous Histiocytoma
• Diagnosis of exclusion .
• The extremities, especially thigh, are the most common
location of this often large mass .
• Lesion may also occur as second malignancy at sites of
previous surgery/radiotherapy .

35. Smooth Muscle Tumors
• Leiomyoma
• Angioleiomyoma
• Leiomyosarcoma.

36. Leiomyoma
• Pelvic tumor seen in females
• The other is tumors occurring in deep soft tissues of either sex –
very rare .
Leiomyosarcoma
• It accounts for about 6 percent cases of deep soft tissue
sarcomas
• shows a more heterogeneous MR appearance. These are large, bulky
masses and seldom show calcification.

37. Skeletal Muscle Tumors
• Rhabdomyoma - commonly found in the heart, while extracardiac
rhabdomyoma is extremely rare .
• Rhabdomyosarcoma .
Rhabdomyosarcoma
 Accounts for more than half of softtissue sarcomas seen in children.
 Arises from primitive mesenchymal cells .
 Common sites : pelvis, head and neck, genitourinary tract and less
often extremities.
MR features :
• well or poorly defined masses with low signal intensity on T1W images,
high signal intensity on T2W images and variable contrast
enhancement .
• Presence of internal necrosis is a poor prognostic sign in neonates.

38. Axial CECT of a 5 years old male patient showing an ill-defined
presacral mass with extension into bilateral gluteal regions (right
> left)
Rhabdomyosarcoma

39. SE T1W (A) and postcontrast sagittal (B) scans showing the tumor
involving all muscle compartments of left leg and inner part of left
thigh with secondary involvement of left tibia and lower end of femur
Rhabdomyosarcoma

40. Chondro-osseous Tumors
Benign tumor - soft tissue chondroma
Malignant lesions
 Mesenchymal chondrosarcoma
 Extraskeletal osteosarcoma.
Mesenchymal Chondrosarcoma
 Common site - craniofacial region .
 MR images, these lesions show heterogeneous high signal intensity
on T2W images with heterogeneous contrast enhancement
 Plain radiographs and CT - Plain radiographs and CT .

41. Chondrosarcoma: MRI shows heterogeneous mass lesion in the medial
compartment of thigh, which is hypointense on T1W image (A) with
hyperintense areas within .On T2W fat-suppressed images (B and C) the
lesion shows high signal intensity
Mesenchymal Chondrosarcoma

42. Extraskeletal Osteosarcoma
• Occur in older patients compared to their osseous counterparts
• Highgrade malignancies and have no attachment to the bone or
periosteum
Plain radiographs and CT
• Amorphous ossification seen in these tumors, which is typically most
prominent in the centre (unlike myositis ossificans).

43. Tumors of Uncertain Origin
Synovial Sarcoma
• Does not arise from the synovium .
• Extra-articular in location, being near the knee joint .
• Adolescents and young adults are most often affected.
• Although the radiographic appearance is not characteristic, the
finding of a soft tissue mass near a joint of a young patient is
highly suggestive .

44. Synovial sarcoma : T1W (A) T2W (B) and postcontrast (C) MR images of a
21-year-old male showing a heterogeneous,
solid, lobulated extra-articular mass located just behind the knee joint.
Intraosseous extension is seen into the adjoining femur
Synovial Sarcoma

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