PMC6558611_01
Initial anteroposterior and lateral radiographs of the right femur. (a) An expansile intramedullary lucent lesion is seen within the subtrochanteric region with no evidence of chondroid calcification. (b) Cortical destruction and lytic expansion of the lesser trochanter. (c) Ground-glass appearance of the mid femoral shaft with a sclerotic rim compatible with fibrous dysplasia.
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Initial radiographs demonstrated a lucent intramedullary lesion within the subtrochanteric region:further characterized by a focally aggressive appearance with cortical destruction and lytic expansion of the lesser trochanter (Figures 1(a) and 1(b)). A ground-glass appearance, typical of fibrous dysplasia, was also noted in the mid-femoral shaft (Figure 1(c)).
Fat-suppressed T2 MRI of the right femur. (a) Cortical destruction with an extraosseous soft-tissue mass in the region of the lesser trochanter. (b) Intermediate to high signal lesion within the medullary cavity of the proximal and mid right femoral shaft though indolent at the inferior aspect (dashed arrow). T2 hyperintense mass in the distal thigh in line with a myxoma (solid arrow).
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Imaging (MRI) displayed an intermediate to high signal lesion within the medullary cavity of the proximal and mid right femoral shaft (Figure 2(a)). In line with the initial radiographs in which two benign sites of fibrous dysplasia were noted, in the third proximal lesion, there was cortical destruction with an extraosseous soft-tissue mass in the region of the lesser trochanter. Additionally, in keeping with the known myxoma, a soft-tissue T2 hyperintense mass within the medial distal thigh was also present (Figure 2(b)).
Gross pathology of the right femur. (a) Cut section of the femur showing an infiltrative, hard, tan-white tumor within the medullary cavity (arrows) invading the medial cortex and extending to soft tissue (triangle). (b) An infiltrative, hard, tan-white tumor (A), well-distinct white areas (B), and well-circumscribed soft-tissue myxoid lesion (C) corresponding microscopically to an osteosarcoma (A), fibrous dysplasia (B), and myxoma (C).
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Along with bony specimens, one of the soft-tissue masses was also excised and sent to pathology for investigation (Figures 3(a) and 3(b)).
Microscopic hematoxylin and eosin stain sections of right femur tissue. (a) Osteosarcoma with osteoblastic component including neoplastic osteoid formation (triangle) and (b) markedly pleomorphic tumor cells. (c) Fibrous dysplasia with irregular bony spicules and trabeculae (BT) with fibrous stroma (ST). (d) Myxoma composed of hypocellular and hypovascular stromata (ST) containing abundant myxoid matrix and bland spindled cells.
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Pathology later confirmed a high-grade osteosarcoma in the setting of fibrous dysplasia and a benign myxoma (Figures 4(a)-4(d)).