Dermal analogue tumours of major salivary glands.

Monomorphic adenomas of the major salivary glands manifest a histologic spectrum whose diversity rivals that of pleomorphic adenomas. In nearly all forms of monomorphic adenomas there are histologic features which recall stages in the embryonic development of salivary glands and/or adenexae of skin. A close histogenetic relationship between certain monomorphic adenomas and certain adenexal tumours of skin is suggested by the findings of this report. Within the diversity of expression found in monomorphic adenomas are subsets of tumours which are analogous and nearly homologous with dermal appendage tumours, especially the dermal eccrine cylindroma. The analogous relationship is carried further by a proposed diathesis in which patients exhibit histologically similar tumours in their salivary glands and skin.