The term cylindroma has been used by various authors to designate different tumors, which are most likely of diverse histogenesis. The name was first applied to an encapsulated orbital tumor, by Billroth1 in 1856. He recognized in this neoplasm on gross examination two intertwining systems of cylinders, one composed of parenchymal cells and the other of hyaline or mucous stroma. The latter gave to the neoplasm a characteristic glassy appearance. Although Billroth regarded these as epithelial neoplasms, the cylindromatous appearance is due mostly to the stroma and only in slight part to the parenchyma. Although the term cylindroma is retained because of its descriptive as well as its historical value, it must be emphasized that it refers to a special type of mixed tumor in which the cylindromatous appearance predominates. The recognition of this entity has a deeper significance in that it implies a kinship to basal cell carcinoma. Because