Sebaceous lymphadenoma: ultrastructural observations and lipid analysis.

Sebaceous lymphadenoma is a rare, benign neoplasm of the parotid gland. In the 18 years since the initial report seven additional cases have been published. None includes ultrastructural studies or lipid analysis. Electron microscopy shows that the epithelial cells undergo a progressive maturation from basal to the typical lipid-laden mature sebaceous cells as in the cutaneous sebaceous glands. No morphologic differences are found between cutaneous sebaceous glands and the sebaceous glands in this parotid neoplasm. Thin-layer chromatography demonstrates the same type of lipids in the subaceous lymphadenoma as well as in cutaneous sebaceous glands. These findings suggest that the parotid salivary gland may be ectodermally rather than endodermally derived.