Myxoid leiomyosarcoma of the uterus. Report of a case with cytologic findings.

BACKGROUND: Myxoid leiomyosarcoma is a rare variant of uterine sarcoma, exhibiting malignant biologic behavior despite the absence of cytologic atypia and of significant mitotic activity. CASE: A 20-year-old female was referred with a cystic pelvic mass. At laparotomy, the tumor, weighed 2,200 g and originating in the left lateral uterine wall, was removed. Microscopic examination revealed well-differentiated smooth muscle cells without atypia and with a few mitotic figures in the copious myxoid matrix, suggesting myxoid leiomyosarcoma. Three years following laparotomy, an irregular mass around the uterus was noted on sonographic examination, suggesting local recurrence. Two years and six months later, the second operation was performed, and a locally recurrent, multicystic tumor weighing 3,500 g was excised. The histopathology was similar to that of the primary tumor. Cytologic findings on imprint material from the tumor revealed a few isolated or sheet like small cells consisting of spindle and polygonal cells with round and oval nuclei. Cytologic atypia was also minimal.
CONCLUSION: Myxoid leiomyosarcoma should be included in the differential diagnosis of smooth muscle neoplasia.