Paget's disease is a chronic bone disorder characterized by abnormal bone remodeling. It commonly affects the pelvis, spine and skull. Radiography is often used to evaluate Paget's disease and detect characteristic features like thickened bone and osteolytic lesions. While some cases are asymptomatic, complications can include fractures, osteoarthritis, nerve entrapment and rare neoplastic transformations. MRI and bone scintigraphy provide additional information about disease activity and complications.

1. Dr/ ABD ALLAH NAZEER. MD.
Radiological imaging of Paget's disease.

2. Paget disease (osteitis deformans) is a chronic skeletal disorder
characterized by abnormal and excessive remodeling of bone. The
disease was named after Sir James Paget who described the condition
in 1877 in a detailed essay recognized in the medical literature as “a
lesson in accurate and lucid writing” . Paget disease is estimated to
affect approximately 3–4% of individuals older than 40 years and is
the second most common bone disease after osteoporosis that affects
the growing population of older persons in the United States.
Abnormal osseous resorption and apposition in Paget disease produce
variable clinical and imaging manifestations. Although the disease
may be asymptomatic, it can be painful or deforming and associated
with various and debilitating musculoskeletal complications.
Radiologists play a central role in the imaging diagnosis of the
process and its multifaceted manifestations. Radiography remains the
most inexpensive method to evaluate patients with Paget disease of
bone. CT, bone scintigraphy, and MRI have complementary roles in
achieving the correct diagnosis of Paget disease and its complications.

3. Paget disease of bone
Paget disease of the bone is a common, chronic bone
disorder characterised by excessive abnormal bone
remodelling. It frequently affects the pelvis, spine, skull
and proximal long bones and has characteristic
radiographic features.
Epidemiology
It is relatively common and can affect up to 4% of
individuals over 40 and up to 11% over the age of 80.
There may be a slight male predilection. Incidence can be
considerably higher in the United Kingdom than in other
countries. It is also common in Australia, New Zealand,
Western Europe, and the United States.

4. Clinical presentation
The majority (approximately three-quarters) of patients are
asymptomatic at the time of diagnosis. Presenting symptoms include:
localized pain and tenderness
increased focal temperature due to hyperaemia (due to
hypervascularity)
increased bone size: historically changing hat size was a giveaway
bowing deformities
kyphosis of the spine
decreased the range of motion
signs and symptoms relating to complications (see below)
Polyostotic disease is more prevalent than the monostotic type. The
most frequent sites of involvement are:
spine
pelvis (often asymmetric)
skull
proximal long bones

5. Pathology
The etiology is not entirely known, but it is a disease of
osteoclasts. Viral infection (paramyxovirus) in association
with genetic susceptibility has been postulated.
There are three stages classically described (but is part of
continuous spectrum)
lytic (incipient active): predominated by osteoclastic
activity
mixed (active): osteoblastic as well as osteoclastic activity
sclerotic/blastic (late inactive)
Markers
serum alkaline phosphatase (ALP) elevated
normal calcium and phosphorous levels
urine hydroxyproline increased

6. Natural history and skeletal distribution:
The primary event in Paget disease is intense focal resorption followed by
disorderly bone formation that results in overall abnormal bone
remodeling. Paget disease generally is considered a relentlessly progressive
disorder that evolves through various stages or phases of activity followed
by an inactive or quiescent stage. There is notable variability in the rate of
disease progression from one patient to another or in a single individual.
Three major phases are recognized: the lytic phase (incipient active), in
which osteoclastic resorption predominates; the mixed phase (active), in
which there is both osteoclastic and osteoblastic hyperplasia with
predominant osteoblastic activity; and finally, the blastic phase (late
inactive), in which osteoblastic activity gradually declines. These three
phases of the pagetic process—coupling abnormal osseous resorption and
apposition within the periosteal and endosteal cortical envelopes—account
for the variable radiographic appearances of the disease. As a result of this
anarchic bone behavior that produces disorganized new bone (mosaic), an
increased or decreased external bone contour and a narrowed or enlarged
marrow cavity are seen, as opposed to bone expansion that was long
regarded as a universal feature of the disease.

7. The anatomic distribution of Paget disease usually is
asymmetric and most commonly affects the lumbar spine (30–
75%), pelvis (30–75% of cases), sacrum (30–60%), femur (25–
35%), and cranium (25–65%). Less frequently, however,
cervical and thoracic involvement can be observed. There is a
preference for the lower extremities and a tendency for right-
sided alterations. The shoulder girdle, particularly the
proximal humerus (31%) and scapula (24%), are less
commonly affected sites. Pagetic involvement of the ribs,
fibula, and small bones in the hands and feet is infrequent.
Polyostotic disease (65–90%) is more frequent than
monostotic disease. In some patients, however, the disease is
initially or totally monostotic, a pattern that is evident in 10–
35% of cases. Monostotic Paget disease appears to
predominate in the axial skeleton, although every bone in the
skeleton can be the sole site of involvement.

8. Radiographic features
Plain radiograph
The early phase features osteolytic (lucent) region which is later followed by
coarsened trabeculae and bony enlargement. Sclerotic changes occur much later in
the disease process.
Skull
osteoporosis circumscripta: large, well-defined lytic lesion
cotton wool appearance: mixed lytic and sclerotic lesions of the skull
diploic widening: both inner and outer calvarial tables are involved, with the
former usually more extensively affected
Tam o'Shanter sign: frontal bone enlargement, with the appearance of the skull
falling over the facial bones, like a Tam o' Shanter hat
Spine
picture frame sign: Paget disease of the spine frequently manifests with cortical
thickening and sclerosis encasing the vertebral margins, which gives rise to the on
radiographs in mixed phase disease
squaring of vertebrae: on lateral radiographs flattening of the normal concavity of
the anterior margin of the vertebral body also adds to the rectangular appearance
vertical trabecular thickening: in Paget disease is coarser than the more delicate
pattern seen in hemangiomas with which it can be confused

9. Pelvis
cortical thickening and sclerosis of the ileopectineal and ischiopubic lines
acetabular protrusio
enlargement of the pubic rami and ischium
These findings are often asymmetric and for some reason, may be more commonly seen on
the right side.
Long bones
blade of grass or candle flame sign: begins as a subchondral area of lucency with
advancing tip of V-shaped osteolysis, extending towards the diaphysis
in rare cases, the disease is isolated to the diaphysis, most commonly in the tibia,
rather than subchondral bone, which can cause diagnostic confusion
lateral curvature (bowing) of the femur
anterior curvature of the tibia
Signs: Paget disease related signs include:
Tam o' Shanter sign
blade of grass sign
osteoporosis circumscripta
jigsaw pattern bone or mosaic pattern bone
picture frame vertebra
cotton wool appearance of bone
banana fracture
Looser zones
ivory vertebra sign

10. MRI
The overall signal characteristics are variable, likely reflecting the natural course
of the disease process in different phases.
Several major patterns of involvement have been described
dominant signal intensity in pagetic bone similar to that of fat; most common
pattern: probably corresponds to the early mixed active phase
relatively low T1 and high T2 signal alteration (also referred as a “speckled”
appearance); second most common pattern: probably corresponds to granulation
tissue, hypervascularity, and edema seen in active disease
low signal intensity on both T1 and T2 images: suggesting the presence of
compact bone or fibrous tissue; least common pattern: seen in late blastic inactive
phase
Fatty marrow signal is usually preserved in all sequences unless there is a
complication.
Bone scintigraphy
Tc99m-MDP
highly sensitive but not specific
traditionally has been said to demonstrate marked increased uptake in all
phases of the disease, although in the burnt out sclerotic quiescent phase
uptake may be normal.

11. Complications of Paget disease:
Common complications of Paget disease include osseous deformities,
fractures, Osteoarthrosis, basilar impression, spinal stenosis, and neurologic
abnormalities. Other less commonly encountered complications are bone
tumor, soft-tissue mass, osteomyelitis, extramedullary hematopoiesis,
rheumatoid arthritis and its variants, and crystal deposition disease.
Arthropathy Osteoarthrosis is a common complication in Paget disease. This
complication results from altered biomechanics across grossly abnormal
bones and joints, producing cartilaginous and osseous degeneration. The hip
and the knee are the articulations most frequently affected. The pattern of
narrowing of the articular space in Paget disease differs in appearance from
that in primary degenerative joint disease. With acetabular involvement,
either medial or axial joint space narrowing is seen; with involvement of both
the acetabulum and the femoral head, axial joint space loss can occur; and
with isolated femoral head involvement, superior joint space loss is noted.
Acetabular protrusion may complicate pagetic involvement of the
acetabulum. Notably, the formation of osteophytes is not a prominent
feature of the disease. Rheumatoid arthritis and its variants, as well as
crystal deposition arthropathy, also have been associated with Paget disease.

12. Deformity and Fracture In Paget disease, overall abnormal bone formation results in
osseous weakening, with deformity and fractures being common manifestations of the
disease. Anterior or lateral bowing of the tibias or femurs is typical. In the spine, bowing
results in kyphosis; in the hip, deformity may manifest as protrusio acetabuli.
Fracture is the most common complication of Paget disease, which can be crippling
because of the high frequency of nonunion in diseased bone. Insufficiency fractures
appear as single or multiple linear cortical radiolucent areas on the convex surface of
the long bones and are designated “banana fractures”. These pathologic fractures
usually occur in the femur, tibia, humerus, pelvis, and spine. In the femur, which is the
most common site of fracture, fractures are usually subtrochanteric in location, followed
in decreasing frequency by the upper third of the femoral shaft and the femoral neck.
Neurologic Entrapment Neurologic deficits in Paget disease may relate to
abnormalities at the base of the skull or the spine. Calvarial enlargement can cause
cranial nerve compression with neurosensory disturbances, deafness, blindness, muscle
palsies, and trigeminal neuralgia. Basilar impression, hydrocephalus, and
vertebrobasilar insufficiency are additional complications of Paget disease affecting the
craniocervical junction. Spinal stenosis, compression of the spinal cord, and cauda
equina can be caused by enlargement of the pagetic vertebral bodies or posterior
elements, spinal deformity and fracture, vertebral collapse with hemorrhage, vascular
compromise, or secondary neoplasm. Entrapment of the sciatic nerve may present
between an enlarged ischium and lesser trochanter or between the abnormal ilium and
piriformis muscle.

13. Neoplasms Neoplastic involvement complicating Paget disease is unusual and includes
sarcomatous transformation; giant cell tumor; and superimposed tumorous conditions,
such as metastatic disease, plasma cell myeloma, and lymphoma. The reported frequency
of sarcomatous degeneration varies according to the extent of the pagetic process. In
patients with widespread skeletal involvement, sarcomatous degeneration may occur in 5–
10% of cases, whereas in patients with less extensive skeletal disease, neoplasm may occur
in fewer than 1% of cases. Patients usually are between 55 and 80 years old, with men
affected more commonly than women (2:1 ratio). Clinical findings include focal pain,
swelling, or pathologic fracture. Although virtually any bone can be involved, the bones
most commonly affected are the femur, the pelvic bones, and the humerus and
occasionally the skull and vertebral column. Osteosarcoma predominates (50–60% of
cases) followed by malignant fibrous histiocytoma or fibrosarcoma (20–25%);
chondrosarcoma (10%); and, less commonly, lymphoma and angiosarcoma (1–3%).
The radiographic findings of malignant transformation comprise osteolysis, cortical
destruction, bony speculation, no healing fracture, and a soft-tissue mass. Osteosclerosis or
periostitis is infrequent. On bone scans, sarcomatous degeneration may appear as a “cold”
area of absent uptake, representing decreased accumulation of the tracer at the site of
neoplasm and necrosis. On CT images, neoplastic involvement in pagetic bone appears as
osseous destruction and an extra-osseous mass. MRI shows nonspecific signal intensity
characteristics of low to intermediate signal intensity on T1-weighted images and
inhomogeneous low to high signal intensity on T2-weighted images in affected bone.
Prominent inhomogeneous enhancement in pagetic bone complicated by neoplastic
disease is evident after the IV administration of contrast material.

14. Giant cell tumor is another type of neoplasm associated with Paget disease,
although this association is very rare and has been considered by some
authorities a giant cell reparative granuloma. The tumor almost always
occurs in the skull or the facial bones, but giant cell tumor can involve the
pagetic pelvis, the clavicle, the spine, and the tubular bones. Patients with
giant cell tumor complicating Paget disease in general are elderly persons and
have polyostotic involvement. Notably, the tumor more frequently is benign
than malignant and may show dramatic response to the use of steroids alone.
On radiographs, the tumor appears as a lytic expansile lesion with or without
an associated soft-tissue mass. MR images display an osseous segment with
the variable signal characteristics of pagetic bone and a soft-tissue
component of intermediate signal intensity on T1-weighted images and of
focal increased signal on T2-weighted images. Cystic and hemorrhagic regions
may be present in the tumor.
Although reportedly rare, metastatic disease involving either the non pagetic
bones or the pagetic bones may be associated with Paget disease. A lytic
lesion within sclerotic bone and a soft-tissue mass may be seen in patients
with metastases superimposed on Paget disease . Other neoplastic conditions
complicating Paget disease include plasma cell myeloma, lymphomas, and
leukemia's, although these associations may be random.

15. Frontal radiograph of right tibia of 67-year-old woman with Paget disease shows well-defined
wedge area of osteolysis (arrow) in diaphysis of tibia and blade-of-grass appearance.

16. Lytic phase of Paget disease (“blade-of-grass” appearance) of the appendicular skeleton in
different patients. (a) Anteroposterior radiograph of the knee in a 74-year-old man shows a
large area of lysis beginning in subchondral bone with a sharp inferior margin
(arrowheads). (b) Lateral radiograph of the upper tibia in a 41-year-old man shows a lytic
lesion in the tibial tubercle, with blade-of-grass appearance superiorly and inferiorly (arrows).

17. Non-complicated active Paget disease of the left distal tibia in an asymptomatic 45-year-old man with fibrovascular
marrow. (a) Anteroposterior radiograph of the ankle shows typical cortical and trabecular thickening from Paget
disease. (b) Coronal T1-weighted MR image (500/14) reveals patchy marrow replacement in the left distal tibia, although
small foci of maintained yellow marrow are seen (arrows). (c) Axial fat-suppressed T1-weighted MR image (600/15) obtained
after intravenous injection of gadolinium reveals patchy speckled enhancement in the marrow space (*) and particularly
prominent intracortical enhancement (arrowheads). (d) Axial fat-suppressed T2-weighted (5,333/84) MR image shows
heterogeneous speckled high signal intensity in the marrow (*) without cortical destruction or soft-tissue mass.

18. Lateral skull radiograph of 67-year-old woman with Paget disease
shows area of osteolysis (arrowheads) in frontal region that is
designated “osteoporosis circumscripta” in lytic phase of Paget disease.

19. Lytic phase of Paget disease of the skull in different patients with osteoporosis circumscripta. (a) Lateral radiograph of a 50-year-old man shows a well-defined area of lysis in
the frontal and occipital regions (arrowheads). (b) Lateral radiograph of a 60-year-old woman with osteoporosis reveals frontal and occipital areas of osteolysis (*) that are
more difficult to detect in this clinical setting. (c) Bone scan of the same patient as in b reveals intense uptake of radionuclide in the frontal and occipital areas, as well as in the
face. (d) Axial CT scan of a 55-year-old man with mild expansion of the head reveals a lytic lesion with sharp borders (arrows) in the frontal bone. (e) Photograph of a whole-
mounted, longitudinal section of the calvaria (H-E stain) shows calvarial expansion and extensive fibrovascular tissue in the diploic space (*).

20. Blastic phase of Paget disease involving the
calvaria. (a) Lateral radiograph of the skull in a
56-year-old man shows diffuse calvarial thickening
including the calvaria and maxillary sinus region,
with several areas of focal sclerosis (“cotton wool”
appearance) (arrowheads). (b) Lateral radiograph of
a skull specimen from an 85-year-old woman reveals
diffuse sclerosis and calvarial thickening with
platybasia. (c) Axial CT scan (same case as b) also
reveals the posterior thickening and mixed lysis and
sclerosis (area between arrows).

21. Lateral skull radiograph of 64-year-old woman with Paget disease reveals several areas of focal
sclerosis (arrowheads) that produce cotton-wool appearance. There is diffuse calvarial thickening.

22. Cotton wool appearance : A plain radiograph sign of late stage Paget Disease.
Its appearance is due to thickened, disorganized trabeculae which lead to
areas of sclerosis in a previously lucent area of bone – typically the skull.

23. Paget disease of the skull base in a 70-year-old man. Axial CT scan demonstrates
diffuse expansion and sclerosis of the bones of the skull base, characteristic of Paget
disease. Note the sparing of the maxillofacial bones, which, along with the age of the
patient, is a helpful feature in differentiating it from fibrous dysplasia.

24. Radiography of the skull (Panel A) showed thickening of the outer and inner tables of the cranial bones,
widening of the diploë, and a “cotton wool” appearance caused by irregular areas of sclerosis (arrows).
Computed tomography of the skull (Panel B) confirmed bony expansion, cortical bone thickening, and
irregular areas of sclerosis (arrows). These imaging findings reflect the mixed osteolytic and osteoblastic
phases of Paget's disease, resulting in accelerated bone turnover with bone deposition and expansion.

25. Paget's Disease with diffuse calvarial thickening.

26. Paget disease of skull. A and B, Axial T1-weighted (TR/TE, 400/20) (A) and T2-weighted (4300/100) (B) MR images of head
exhibit abnormal heterogeneous, decreased signal intensity in expanded calvaria. Several areas of low signal intensity
(arrowheads) representing focal osteosclerosis are seen. C, Axial CT image shows marked calvarial thickening and sclerosis.

27. Non complicated Paget disease of the skull in a 72-year-old woman. Axial T1-weighted (600/20) (a) and
T2-weighted (4,000/75) (b) MR images of the head show diffuse calvarial thickening that remains low
signal intensity with both pulse sequences (*). Radiograph (not shown) revealed diffuse sclerosis.

28. Paget disease complicated with basilar impression in 65-year-old woman. Sagittal T1-weighted MR
image (TR/TE, 500/16) displays basilar impression and compression of anterior aspect of pons. Note
marked deformity of tip of odontoid process that may be related to pagetic process. Cerebellum (C) is
also compressed. Basilar impression is diagnosed when tip of odontoid process (arrow) projects more
than 5 mm above Chamberlain line, which is drawn from hard palate (HP) to basiocciput (O). Calvaria
(arrowheads) appears expanded and displays heterogeneous, predominantly low signal intensity.

30. Frontal radiograph of 62-year-old man with Paget disease shows thickening
of ileopectineal (arrow) and ilio ischial (arrowhead) lines on right side of pelvis.
Coarse trabeculation and bone sclerosis are also evident as compared with
uninvolved side. Contrast medium is noted in urinary bladder.

31. Frontal radiograph of 57-year-old man with Paget disease reveals cortical thickening (arrowheads)
encasing entire T11 vertebral body at all four margins, which manifests as picture-frame
appearance. Vertebral body is enlarged and mildly compressed, and osteophytes are seen.

32. Paget disease of the spine in different patients. (a) Anteroposterior radiograph of the lumbar spine in a 45-year-old man shows subtle
vertical trabecular thickening (white arrowheads) and early picture frame appearance with condensation of trabeculae about the
superior and inferior endplates (black arrowheads). (b) Lateral radiograph of the lumbar spine in a 54-year-old woman shows cortical
thickening (picture frame appearance) about the entire vertebral body at all levels (arrowheads). (c) Sagittal CT reformatted image in a
50-year-old man shows similar trabecular thickening (arrowheads) with extension into the posterior vertebral elements (*).

33. Ivory vertebral body caused by Paget disease in a 50-year-old asymptomatic
man. (a)Anteroposterior radiograph shows diffuse sclerosis in the T10 vertebral
body. (b) Posterior bone scan reveals intense radionuclide uptake at the involved
vertebral level (see Fig 5d for histologic specimen of an ivory vertebral body).

34. Paget disease of spine in different patients. A, Axial CT scan of T11 vertebra in 57-year-old
man shows mixed lytic and sclerotic changes involving vertebral body and arch.
B, Axial CT scan of 60-year-old man shows predominant osseous sclerosis of L5 vertebral
body, ivory vertebra, that is extending into posterior osseous elements.

35. Non complicated Paget disease of the calcaneous in a 58-year-old asymptomatic man.
Sagittal T1-weighted (repetition time msec/echo time msec = 500/20) (a) and T2-
weighted (2,000/80)(b) MR images show cortical and trabecular thickening
(arrowheads) with maintained yellow marrow (*). In fact, there is more fat in the
affected calcaneal marrow, compared with that in the noninvolved talus.

36. Images obtained of 73-year-old woman with Paget disease at femur. A, Frontal radiograph of distal femur reveals
coarsened trabeculae, cross-hatched pattern (arrowheads), and cortical thickening (arrow). B, Axial T1-weighted MR
image (TR/TE, 450/16) shows thickened trabeculae (arrowheads) within maintained yellow marrow (asterisk). Cortical
thickening (arrows) is appreciated. Preservation of medullary fat in femur excludes superimposed sarcoma. C, Axial T2-
weighted MR image (3700/80) shows trabecular thickening (arrowheads) with pagetic bone marrow (asterisk) displaying
high signal intensity similar to that of fat. Fat-saturated MR image would have allowed better characterization of process.

37. Non complicated Paget disease of the distal femur in a 57-year-old woman. (a)Anteroposterior radiograph of the
knee shows typical cortical and trabecular thickening of the entire distal femur to subchondral bone. (b) Coronal
T1-weighted MR image (600/20) shows identical changes with maintained yellow marrow (*) between thickened
trabeculae. (c) Coronal fat-suppressed short-inversion-time inversion-recovery MR image (2,000/30/100) reveals
mild increased signal intensity in the marrow resulting from small fibrovascular elements

38. A, Lateral radiograph shows picture-frame appearance of Paget disease with condensation of trabeculae at
periphery of T11 vertebral body. There is mild straightening of normally concave anterior surface of bone. B and
C, Sagittal T1-weighted (TR/TE, 500/15) (B) and fat-suppressed T2-weighted (5000/90) (C) MR images display
abnormal intermediate and heterogeneous high signal intensity, respectively, in posterior aspect of T11
vertebra (arrows). Note coarsened trabeculae, in anterior aspect of vertebral body (asterisk, B). D, Sagittal fat-
suppressed T1-weighted MR image (550/19) obtained after gadolinium administration reveals marrow
enhancement (black arrowhead) and marked cortical enhancement (white arrowheads) in involved vertebra.

39. Mixed lytic and blastic Paget disease of the spine simulating malignant
transformation in a 60-year-old man. (a) Lateral radiograph of the thoracic
spine shows typical picture frame appearance of Paget disease with cortical
and trabecular thickening (arrowheads). (b) Axial CT scan reveals similar
changes with a focal area of lysis posteriorly (arrows) that could be caused
by lysis from Paget disease or malignant transformation. (c) Sagittal T1-
weighted (600/25) MR image shows patchy areas of maintained yellow
marrow signal intensity in the area of concern posteriorly (arrow), a finding
that excludes malignant transformation. (d) Sagittal T2-weighted
(2,500/90) MR image reveals high signal intensity in the lytic focus
posteriorly (*), but there is no epidural soft-tissue mass. This area remained
unchanged for 5 years and represents a lytic component of Paget disease.

40. Paget’s disease of T11 and T12 showing an increased amount of high MR signal (solid white arrow) in the posterior epidural
space at these levels on a sagittal T2-weighted, b sagittal T1-weighted and c axial T1-weighted images. This can be mistaken for
epidural lipomatosis. However, the d CT sagittal and e axial images demonstrate this to be due to the fat density (solid white
arrow) within the expanded posterior neural arch involved in PD. The axial images (c,e) were obtained at the level of the tip of
the solid arrows on sagittal images. There is also fusion of the vertebrae (dashed arrow) across the intervertebral disc. The
combination of anterior and posterior vertebral involvement in this case resulted in severe spinal canal narrowing and cord
compression. Note the high T1 signal indicating a high fatty marrow content within the pagetic T11 and T12 vertebrae.

41. Paget disease: Both the L1 and L2 vertebral bodies (together with their respective posterior elements)
are involved, with the vertebral bodies expanded in the antero-posterior dimension and L2 a characteristic
“picture frame” vertebra. There is involvement as well of the pelvis together with the sacral vertebral
bodies. Coarse and thickened trabeculae are particularly evident in the iliac bones bilaterally.

42. Paget disease complicated with degenerative joint disease in 70-year-old man. Frontal radiograph shows
pagetic involvement of right hemipelvis with trabecular thickening and sclerosis in ilium and along
ileopectineal and ilio ischial lines. Involvement of subchondral bone of ilium around acetabulum is remarkable.
Symphysis pubis appears enlarged on right side. Joint space loss in superior and axial aspects of hip and mild
protrusio acetabuli are noted. Osteophytes are not prominent. Urinary bladder stone is present.

43. Paget disease of the hip with osteoarthritis. Anteroposterior radiograph of the left hemipelvis shows extensive
Paget disease with osteoarthritis involving the hip. The axial pattern of narrowing of the hip (arrowheads) is
unusual and is likely caused by the underlying osseous weakening and mild protrusio acetabuli.

44. Anterior bone scan of 67-year-old woman with Paget disease
shows intense, increased radionuclide uptake in right hemipelvis.

45. Paget disease complicated with deformity and fracture. Frontal radiograph of 73-year-old woman
shows lateral bowing and bone widening of both femurs. Cortex is thickened and cortical
encroachment on medullary canal is seen. Large fracture line (arrow) extends across mid diaphysis of
left femur. Left femoral shaft displays subtle un-displaced “saw-cut” fatigue fractures (black
arrowheads). In femur, fatigue fractures typically occur along lateral cortex, where tensile forces are
greatest, leading to lateral bowing. Stress fracture (white arrowhead), which will most likely progress
to complete fracture, is barely seen in lateral cortex of right femur.

46. Paget disease of the spine with associated fracture
in a 50-year-old woman. (a) Lateral radiograph of
the lumbar spine shows the typical picture frame
appearance of Paget disease with severe
compression (vertebrae plana) at L4.
Paget disease with both incomplete and complete
fractures of the femur in a 70-year-old
woman. (a) Anteroposterior radiograph of the femur
shows pathognomonic changes of Paget disease: cortical
and trabecular thickening extending to subchondral bone
and subtrochanteric complete fracture. Additional
incomplete fractures (arrowheads) are seen along the
lateral convex femoral surface with callus formation.

47. Transport of Paget disease from iliac crest bone graft donor site to
engrafted proximal tibial area in a 64-year-old
man. (a) Anteroposterior radiograph of the knee shows a
depressed lateral tibial plateau fracture (arrow) sustained in a
motor vehicle accident. (b) Postoperative anteroposterior
radiograph shows bone graft and elevation of the depressed
fragment fixed by a single lag screw. (c, d) Follow-up
anteroposterior radiographs obtained 2 (c) and 3 (d) years later
show progressive development of characteristic Paget disease with
cortical (large arrow) and trabecular (small arrows) thickening and
a sharply defined, blade-of-grass lucent area
(arrowheads). (e) Radiograph of the pelvis reveals extensive Paget
disease throughout the pelvis and proximal femora, including the
bone graft donor site (*) in the left iliac crest.

48. Recurrent lytic phase of Paget disease after tibial tubercle avulsion with fixation and non-weight-bearing in a 75-
year-old man. (a) Lateral radiograph of the lower leg shows an avulsion of the patellar tendon attachment at the
tibial tubercle (black arrow). Changes of Paget disease, with trabecular and cortical thickening (white arrow), are
subtle. (b, c) Follow-up anteroposterior radiographs obtained 2 weeks (b) and 2 months (c) after screw fixation,
bracing, and non-weight-bearing reveal progressive osteolysis (white arrowheads) with apparent focal destruction of
the medial cortex (open arrow). Changes of Paget disease with trabecular (black arrowheads) and cortical (curved
arrow) thickening and sharp inferior margin of lysis (solid straight arrow) are now more apparent.

49. Paget disease of leg bone

50. Paget disease complicated with malignant transformation in 81-year-old man with long history of
disease. Analysis of biopsy specimen proved lesion to be osteosarcoma. A, Radiograph shows
extensive bone destruction with osteolysis and cortical loss in distal portion of humerus. Remainder
of bone shows changes of Paget disease. Associated soft-tissue mass is readily apparent.
B, Corresponding transverse CT image reveals pagetic involvement of humerus.

51. Sarcomatous transformation to osteosarcoma of Paget disease of the humerus in a 77-year-old
woman. (a) Anteroposterior radiograph of the humerus shows typical cortical and trabecular thickening from Paget
disease involving the entire humerus and lateral bowing. Area of medullary sclerosis with mineralization in the soft
tissue is also seen (arrowheads). (b) Sagittal T2-weighted (3,500/105) MR image reveals focal marrow replacement
and associated soft-tissue mass (*). (c)Anteroposterior radiograph and photograph of the coronally sectioned gross
specimen show the osteosarcoma (*) in the humeral mid shaft and adjacent soft tissues (arrow).

52. Sarcomatous transformation of Paget disease in the tibia to malignant fibrous histiocytoma in a 75-year-old
woman. (a) Lateral radiograph of the tibia shows typical changes of Paget disease, with cortical and trabecular thickening
involving the entire bone and anterior bowing. Focal destruction of the anterior cortex is seen superiorly, with a soft-tissue
mass (arrowhead). (b) T1-weighted (500/20) MR image shows focal marrow replacement at the proximal tibial site of
malignant transformation with cortical destruction and associated soft-tissue mass (*). Yellow marrow signal intensity is seen
throughout the remainder of the tibia. (c) T1-weighted (500/20) MR image obtained with gadolinium shows marked
enhancement. T2-weighted MR image (not shown) revealed similar high signal intensity in the sarcoma.

53. GCT of the face associated with Paget disease. (a) Axial CT scan
shows characteristic thickening and sclerosis of the diploic space
(arrows) caused by Paget disease. Expansile mass involving the
maxillary sinus (*) represents the associated GCT. (b, c) Coronal
T1-weighted (500/20)(b) and T2-weighted (2,500/80) (c) MR
images obtained after intravenous injection of gadolinium also
reveal Paget disease with calvarial thickening and maintained
yellow marrow signal intensity (arrowheads). The maxillary GCT
shows focal expansion, intermediate signal intensity with both
pulse sequences, and mild diffuse enhancement (*).

54. Whole Body Bone Scan indicating Paget's disease.

55. Bone scan of a patient who has Paget's disease. The images were
acquired 2.5 h after injection of 925 MBq of 99mTc-methylene diphosphate.

56. Polyostotic Paget disease with multiple static planar bone Scintigraphic images showing increased tracer uptake
in skull, multiple vertebrae (Mickey Mouse sign), pelvis on both sides, sacrum, and distal one-third of right femur.

57. Paget disease of the skull.

58. Mickey Mouse Sign-increased radiotracer uptake on bone
scan in pedicles and spinous process in Paget's disease.

59. Conclusion:
Paget disease is a common skeletal disorder of middle-aged
and elderly persons characterized by excessive and abnormal
remodeling of bone. The disease varies considerably in severity
and evolves through various phases of activity, followed by an
inactive phase. The radiographic features of Paget disease are
virtually diagnostic, including an initial osteolytic phase and a
subsequent osteosclerotic phase. Bone enlargement with
increased radiodensity, accentuated trabecular pattern, and
deformity is typical. Complications associated with Paget
disease are pathologic fractures, neurologic symptoms,
skeletal deformities, articular derangements, and secondary
neoplasms. CT and MRI help delineate pagetic bone changes
and have prove extremely useful in the diagnosis of
sarcomatous transformation, which constitutes the most
dreaded complication of the disease.

60. Thank You.