Uterus, Lipoleiomyoma

Lipoleiomyoma is a fat containing variant of leiomyoma, a benign smooth muscle neoplasm of the uterus.

Grossly it has soft yellow areas and dense white areas. Microscopically this corresponds to the areas of mature fat and benign smooth muscle proliferation, respectively. The amount of fat is variable; pure lipomas had been described but rare.

HMB45 immunohistochemical staining is negative, which is helpful when PEComa (perivascular epithelioid cell) is on the differential diagnosis.

Lipoleiomyomas are rare. They are included in a group of “leiomyomas with heterologous elements”. Other heterologous elements described in association with leiomyomas are brown fat, skeletal muscle, cartilage and bone.