The differential diagnosis of blue or red-blue subepidermal nodules includes blue nevus, metastatic melanoma, Kaposi's sarcoma, and glomangioma. In the following study, we wish to call attention to the hemangiopericytoma, which may appear as a blue-red nodule clinically resembling a glomangioma. However, the histologic pattern and prognosis are quite distinctive from the glomangioma.
In 1942, Stout1 first described a tumor characterized by the formation of endothelial tubes and sprouts with a surrounding sheath of rounded and sometimes elongated cells. On the basis that these cells were derived from the capillary pericytes described by Zimmerman, Stout suggested that the tumor be called hemangiopericytoma, and he has collected 200 such cases. The literature on the subject has been recently reviewed by Martin, Féroldi, and Cabanne.2