Fig. 3: Case 3. A 46-year-old woman with a gluteal/thigh mass status post resection (ANGPTL2-USP6 fusion). | Modern Pathology

Fig. 3: Case 3. A 46-year-old woman with a gluteal/thigh mass status post resection (ANGPTL2-USP6 fusion).

From: Myositis ossificans-like soft tissue aneurysmal bone cyst: a clinical, radiological, and pathological study of seven cases with COL1A1-USP6 fusion and a novel ANGPTL2-USP6 fusion

Fig. 3

a A lateral radiograph showed a mass with clustered peripheral calcification (arrows) in the left proximal posterior thigh. b Axial T1-weighted and c T2-weighted MR image showed a mass infiltrating the gluteus maximus and hamstring muscles. The mass consisted of an ossified component (arrow) and a nonossified soft tissue component (curved arrows). d A needle biopsy showed solid fibroblastic spindle cell proliferation in a collagenized stroma. e Gross examination showed an ill-defined and lobulated mass with multifocal ossification involving the deep adipose tissue and skeletal muscle. f Both ossified and nonossified components were present on histologic examination. In contrast to other cases with a zonal pattern, the nonossified component composed of spindle cells infiltrated the adipose tissue with multiple haphazard foci of woven bone.

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