Paget Disease



Paget Disease







Imaging Evaluation

The radiographic features of Paget disease correspond to the pathologic processes in the bone and depend on the stage of the disorder. In the early phase, the osteolytic or hot phase, active bone resorption is evident as a radiolucent wedge or an elongated area with sharp borders that destroys both the cortex and cancellous bone as it advances along the shaft. The terms frequently used to describe this phenomenon are advancing wedge, candle flame, and blade of grass (Fig. 29.2). In flat bones such as the calvarium or the iliac bone, an area of active bone destruction known as osteoporosis circumscripta appears as a purely osteolytic lesion (Fig. 29.3). In the skull, most commonly affected sites are the frontal and occipital bones; both inner and outer calvarial tables are involved, but the former is usually more extensively affected.

In the intermediate or mixed phase, bone destruction is accompanied by new bone formation, with the latter process tending to predominate. Bone remodeling appears radiographically as thickening of the cortex and coarse trabeculation of cancellous bone (Fig. 29.4). In the pelvis, cortical thickening and sclerosis of the iliopectineal and ischiopubic lines are present. Pubic rami and ischia may enlarge. In the spine, the thin cortex of the vertebral body, which disappears in the hot phase, is later replaced by broad, coarsely trabeculated bone, forming what appears to be a “picture frame” around the body (Fig. 29.5). In the skull, focal patchy densities with a “cotton ball” appearance are characteristic (Fig. 29.6).

In the cool or sclerotic phase, a diffuse increase of bone density occurs together with enlargement and widening of the bone and marked cortical thickening, with blurring of the demarcation between cortex and spongiosa (Fig. 29.7). Bowing of long bones may become a striking feature (Fig. 29.8). Similar changes are observed in the skull, where obliteration of the diploic space is also a typical feature (Fig. 29.9).

It is important to remember that, since in the long bones Paget disease starts at one articular end and advances to the other, all three phases of the disorder may coexist in the same bone (Fig. 29.10A). Likewise, different phases may coexist in the flat bones or in the spine (Fig. 29.10B).







FIGURE 29.1 Major target sites of Paget disease.






FIGURE 29.2 Osteolytic phase of Paget disease. (A) Anteroposterior radiograph of the lower leg of a 68-year-old woman shows an advancing wedge of osteolytic destruction in the midportion of the tibia (arrow). (B) Magnification study of the midfemur in another patient shows the purely osteolytic phase of Paget disease. In both examples, the lesion resembles a blade of grass or a candle flame. (A, From Sissons HA, Greenspan A. Paget’s disease. In: Taveras JM, Ferrucci JT, eds. Radiology—imaging, diagnosis, intervention, vol. 5. Philadelphia: JB Lippincott; 1986:1-14.)







FIGURE 29.3 Osteolytic phase of Paget disease. (A) Lateral radiograph of the skull of a 60-year-old man shows an osteolytic lesion in the parietooccipital area. This sharply demarcated defect, known as osteoporosis circumscripta, represents a hot phase of the disease. (B) Radionuclide bone scan shows a characteristic localized increased uptake of the radiopharmaceutical tracer resulting in the appearance of a “yarmulke” sign. (C) Lateral radiograph of the skull of a 65-year-old woman reveals osteoporosis circumscripta in the frontoparietal area. (Continued)







FIGURE 29.3 Osteolytic phase of Paget disease. Continued (D) Axial CT and (E) 3D CT reconstruction image of the skull in shaded surface display of another patient with osteoporosis circumscripta show large sharply marginated lytic defect in the right temporal-occipital area (arrows). (Courtesy of Evan Stein, MD, Brooklyn, New York.)

Computed tomography (CT) may demonstrate characteristic features of Paget disease (Fig. 29.11), although it is rarely required. Magnetic resonance imaging (MRI) is occasionally employed to demonstrate cortical and intramedullary involvement better, and to exclude (or confirm) extension of the process into the soft tissues. In general, the pagetic bone exhibits heterogeneous signal intensity. On T1-weighted sequences, intermediate-to-low signal intensity is usually noted. On T2 weighting, the signal may be high, intermediate, or low, depending on the stage of the disease and degree of fibrosis and sclerosis (Figs. 29.12 and 29.13).

Scintigraphy displays increased uptake of bone-seeking radiotracer in all three phases of the disease, but particularly in the hot and intermediate, due to increased vascularity and osteoblastic activity in abnormal bone (Fig. 29.14; see also Figs. 26.10, 29.3B, and 29.9D,E).




Jul 24, 2016 | Posted by in MUSCULOSKELETAL IMAGING | Comments Off on Paget Disease

Full access? Get Clinical Tree

Get Clinical Tree app for offline access