This 74-year-old woman presented with a painful lesion on her arm. The clinician submitted it as a possible neuroma or irritated nevus. Glomus tumors are derived from the temperature-regulatory smooth muscle apparatus designed to shunt blood. Therefore they are not endothelium-derived like most vascular tumors. Glomus and glomangioma can be used interchangably, often reflecting the relative amount of cellular and vascular components. Glomus can be painful, as in this case, and is the "G" of the ANGEL mneumonic for painful cutaneous neoplasms.
At medium power, the lesion consists of a monotonous population of bland pink cuboidal cells. The proliferation is perivascular, and not strictly endothelial. The stroma is edematous with a myxoid quality.