Reactive fibrohistiocytic proliferation simulating fibrous histiocytoma

A pelvic nodule was excised at the time of reexploration of the abdomen in a 32-year-old woman who had previously had a malignant germ cell tumor with a mixed histologic pattern of the right ovary. The 3-cm firm lesion from the right vaginal apex was composed predominantly of spindle cells with a prominent storiform pattern. Some findings, such as the presence of foamy histiocytes and a focal foreign body reaction with polarizable material, were atypical for a lesion otherwise quite acceptable histologically as a fibrous histiocytoma. Ultrastructural findings also tended to support the reactive rather than neoplastic nature of this mass. There is a similarity to the silica reaction described by Weiss and co-workers.