Cotyledonoid leiomyoma of the uterus: report of a case.

A 46-year-old woman presented with a pelvic mass. At the time of operation a large, exophytic, multinodular tumor extended into the peritoneal cavity and right broad ligament from a pedunculated attachment to the uterus in the region of the right cornu. On external examination the lesion had the appearance of cotyledonoid dissecting leiomyoma. On microscopic examination bulbous processes were composed of benign smooth muscle arranged in interlacing fascicles or swirls; there was focal hydropic degeneration. Significant nuclear atypia, mitotic activity, and coagulative tumor necrosis were not encountered. No intravascular involvement was present. There was no demonstrable parent leiomyoma or intramural dissecting component, and thus the case differed from previously reported cases of both cotyledonoid dissecting leiomyoma and intramural dissecting leiomyoma. This tumor represents another variation in the group of benign uterine smooth muscle tumors with unusual growth patterns.