Low-grade XXXX of the proximal humerus.

@entity1 @entity174 @entity1418 @entity5 @entity20392 @entity1492 @entity421 @entity158
We present the clinical, radiographical and pathological features of low-grade @entity1492 of the left proximal humerus in a 23-year-old @entity1 in whom it was necessary to distinguish the @entity5 from @entity20392 , @entity1418 and intramedullary well-differentiated @entity421 . The @entity1 presented with a 10-day history of @entity158 in his left upper arm sustained when trying to break his fall with his left hand when slipping in the street. Plain radiography revealed an expanding multilobular osteolytic lesion from the proximal metaphysis to the diaphysis of his left humerus, accompanied by a pathological @entity174 at the distal portion of the lesion. Open biopsy of the lesion was performed twice; however, a conclusive diagnosis could not be obtained. The @entity1 underwent wide excision and prosthetic replacement of the left proximal humerus. Histologically, the resected @entity5 was composed of both cellular areas and hypocellular areas. Cellular areas revealed a proliferation of bundles of uniform fibroblastic spindle-shaped cells with minimal cellular atypia, mixed with abundant intercellular collagenization. Mitotic figures were occasionally seen. Hypocellular areas showed myxoid features with loose bundles of collagen fibers. The @entity1 demonstrates no evidence of disease 42 months after surgery. It is important to detect the scant atypical cells for the differential diagnosis of low-grade @entity1492 and @entity20392 of bone.
