PMC2647176_01
Imaging findings of fibroblastic osteosarcoma in distal ulna of 37-year-old woman.. A. PA view of right wrist reveals well-marginated osteolytic lesion of slightly expansile nature with suspicious focal cortical disruptions (arrows) in distal ulna metaphysis and epiphysis.. B. Coronal T2-weighted (TR/TE = 2925/54), fat-suppressed MR imaging shows multi-loculated, high signal intensity lesion in distal ulna.. C. Axial T2-weighted (TR/TE = 4319/100) MR imaging shows fluid-fluid levels within cystic lesion.. D. Sagittal T1-weighted (400/18.46) MR imaging reveals cortical disruptions (white arrows).. E. On gadolinium-enhanced, fat-suppressed, T1-weighted (517.9/20) MR imaging, focal enhancement of lesion (white arrows) is noted along with largely non-enhancing portions.. F. Large part of tumor is composed of spindle cells, often in "herringbone" pattern (Hematoxylin & Eosin staining, x200).. G. Focal osteoid production by neoplastic stromal cells (Hematoxylin & Eosin staining, x400).
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F1
Radiographs showed an eccentric radiolucent lesion with endosteal scalloping, cortical thinning, and a minimally bulging contour arising from the metaepiphyseal region of the distal right ulna (Fig. 1A). MR images demonstrated a lobulated, septated lesion with multiple locules containing fluid-fluid levels (Fig. 1B, C). In addition, focal cortical disruptions along the ventral aspect of the distal ulna suggested the presence of pathologic fractures (Fig. 1D). Contrast-enhanced T1-weighted, fat-suppressed images revealed peripheral, septal, solid enhancing portions within the tumor (Fig. 1E). Histologically, the neoplasm consisted of a spindle-cell proliferation that produced a focal "herringbone" pattern (Fig. 1F). The presence of focal osteoid production distinguished this fibroblastic variant of osteosarcoma from malignant fibrous histiocytoma (Fig. 1G).