Epithelioid fibrosarcoma of the ovary

Recently, low-grade fibromyxoid sarcoma/hyalinizing spindle cell tumor with giant rosettes (LGMFS/HSCT) and sclerosing epithelioid fibrosarcoma (SEFS) have come to be recognized as distinctive types of fibrosarcoma. Because their pathological features seem to sometimes overlap, it may be that these tumors belong to a similar entity. We report an aggressive sarcoma with unusual histology arising from the right ovary of a 44-year-old woman. The tumor was 12 cm in size, and there were multiple distant metastases to lung, kidney, stomach and bones. Microscopically, the tumor was composed of broad sheets or variously sized nodules of polygonal epithelioid cells accompanied by hyalinous stroma, resembling SEFS. The hyalinous nodules surrounded by the palisading epithelioid cells, as seen in a rosette of HSCT, were scattered. Between these nodules, spindle cells arranged in fascicles or whorled bundles, mimicking LGMFS, proliferated. Immunohistochemical and ultrastructural analyses revealed fibroblastic differentiation of epithelioid cells and the myofibroblastic nature of the spindle tumor cells. We think the present tumor is a distinctive epithelioid fibrosarcoma with the combined features of SEFS and LGFMS/HSCT, suggesting their intimate relationship.