A 34-year-old black man presented with an asymptomatic coin lesion in the lung. The diagnosis was narrowed to a differential between glomus tumor and hemangiopericytoma. The authors found that the terminology applied to such tumors in the literature is confusing largely because of lack of consistency in criteria used to establish the diagnosis. The authors propose that the term glomus tumor be reserved for tumors composed of endothelial-lined vascular spaces surrounded by smooth muscle cells. Hemangiopericytoma should be used for similar tumors composed of pericytes with or without other types of perivascular mesenchymal cells. According to these criteria, this case is the third glomus tumor reported in the lung.