Frequent detection of androgen receptors in spindle cell lipomas: an explanation for this lesion's male predominance?

Abstract Context.—Spindle cell lipoma (SCL) is a tumor with marked male predilection. We discovered one SCL that exhibited strong immunoreactivity for androgen receptors (ARs) in the spindle cells. Objective.—The hypothesis was that ARs in SCLs would not be rare and that all or nearly all SCLs would be AR positive, perhaps explaining its male predominance. Design.—Twenty-eight cases of SCL (22 men, 6 women) and a control group of 20 conventional lipomas (10 men, 10 women) were stained with monoclonal AR antibody (1: 150; Dako, Carpinteria, Calif) using the Ventana Discovery. Only nuclear reactivity was considered positive, as noted in prostate controls. Cell types (fat, spindle cells) and extent of staining were recorded as rare, considered negative, focal (1+), or diffuse (2+/3+). Results.—All 22 cases of SCL in men were positive for ARs. Twenty showed diffuse (2+/3+) reactivity mainly in the spindle cells. Of the 6 SCLs in women, 1 was AR negative, 1 showed a 3+ reaction in the spindle cells, and 4 had ...