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.
Histologic sections of skin show a well-circumscribed lesion within the deep dermis. The lesion is cellular, and vascular channels are recognized even at low power.