Bizarre epithelioid lipoleiomyoma of the uterus

Lipoleiomyomas of the uterus are extremely rate. All previous examples have been composed of two mature elements: bland spindled smooth muscle cells and bland adipose tissue. We report a unique case of a uterine tumor containing four morphologic cell types: mature spindled smooth muscle cells with and without nuclear atypia, epithelioid smooth muscle cells with and without nuclear atypia, mature adipose tissue, and immature fat cells and lipoblasts with marked nuclear atypia. No mitotic features were noted despite an extensive search. Description of this extremely unusual variant, believed to be the first reported of its kind, should enable pathologists to avoid a diagnosis of malignancy. Further, histologic evidence of a direct metaplasic origin of the adipose differentiation could be found and was supported by immunohistochemical findings.