Glomus tumors are benign neoplasms derived from cells of the neuromyoarterial glomus or glomus body (malignant variants of this tumor, glomangiosarcomas, are discussed in Chapter 11, Part 16). Pulmonary glomus tumors are very rare and generally occur in middle-aged men. Approximately two-thirds of patients are asymptomatic. Pulmonary glomus tumors may be peripheral or central and are generally well-circumscribed gray-tan masses. Differential diagnosis includes carcinoid tumor, hemangiopericytoma, smooth-muscle tumors, paraganglioma, and primitive neuroectodermal tumors.