Cytologic features of a primary myxoid malignant fibrous histiocytoma arising in the uterus - A case report

BACKGROUND: Primary malignant fibrous histiocytoma (MFH) of the uterus is e xtremely rare. The 10 cases reported in the literature all involved the ple omorphic variant, and to the best of our knowledge, the myxoid variant has not been reported before. We describe the cytologic findings of primary ute rine myxoid MFH in relation to the myxoid component, potentially leading to an incorrect diagnosis. CASE: A 68-year-old woman presented with a primary uterine tumor. Endometri al cytology showed numerous loosely arranged, spindle-shaped fibroblastlike cells; atypical histiocytelike cells; and giant cells with a necrotic back ground. The overall cytologic picture was of a degenerated pleomorphic. lei omyosarcoma with an inconclusive diagnosis. A diagnosis of myxoid MFH was e stablished after electron microscopic and immunohistochemical studies of th e primary tumor and tumor transplanted, as primary cultured cells, in nude mice. The patient underwent an exploratory laparotomy and died of tumor pro gression 38 days after the initial consultation, without treatment. CONCLUSION: Because of overlapping cytologic features among uterine sarcoma s with myxoid stroma, it is important to recognize the histiocytic lineage of tumor cells by immunohistochemistry and electron microscopy in various p resentations of fresh samples.