Granular cell myoblastoma of the bronchus

Granular cell myoblastoma is a relatively uncommon lesion of disputed histogenesis which is seen most frequently in the subcutaneous tissues and in the tongue (Strong, McDivitt and Brasfield, 1970). It rarely occurs in the bronchus; Weitzner and Oser in a search of the literature could only find 30 cases to which they added one of their own. Many authors have discussed the origin and nature of the lesion, some regarding it as nonneoplastic, either a degenerative reaction (Ewing, 1940; Willis, 1960) or a storage disorder (Azzopardi, 1956; Shear, 1960), but most regarding it as neoplastic. However, the latter disagree on the cellular origin of the neoplasm, the suggestions being neural (Ashburn and Rodger, 1952; Fisher and Wechsler, 1962), myogenic (Murphy, Dockerty and Broders, 1949), fibroblastic (Pearse, 1950) and mesenchymal (Toto and Restarski, 1967). Reviewing the available evidence and adding evidence of their own from electron microscopic studies, Garancis, Komorowski and Kuzma (1970) have favoured an origin from the Schwann cell and this remains the most popular hypothesis. In view of the rarity of the lesion in the bronchus we would like to discuss briefly the rather unusual bronchographic appearances.