Cytologic features of sebaceous, lymphadenoma, and sebaceous lymphadenocarcinoma: Differential diagnostic...

Sebaceous lymphadenomas and sebaceous lymphadenocarcinomas are uncommon neoplasms occurring predominately within the parotid gland. Cytomorphology of these neoplasms is rarely reported. Occasional reports have discussed the cytomorphological features of these neoplasms but criteria distinguishing sebaceous lymphadenomas from lymphadenocarcinomas have not been described.

The senior authors' consultation files and records of the University of Missouri were searched for all cases with a diagnosis of sebaceous adenoma, lymphadenoma, lymphadenocarcinoma, and adenocarcinoma. Slides from these cases were reviewed by the authors for cytologic features characteristic of these neoplasms. These features were compared with other salivary gland lesions in the differential diagnosis and for utility in separating benign from malignant sebaceous neoplasms.

Three sebaceous lymphadenomas and one sebaceous lymphadenocarcinoma were found. Smears contained large numbers of mature lymphocytes dispersed in a watery or bloody background. Scattered among the lymphoid cells were small nests of epithelial cells characterized by a finely to coarsely vacuolated cytoplasm. The majority of cells contained bland nuclei with finely granular chromatin and conspicuous nucleoli. A second population of small basaloid cells was present. The single sebaceous lymphadenocarcinoma had a similar cytomorphology.

Sebaceous lymphadenomas can be distinguished from other neoplasms within the differential diagnosis due to their prominent lymphoid background and population of epithelial cells with a finely to coarsely vacuolated cytoplasm. The nuclei are bland but have conspicuous nucleoli. Based on our small series, cytomorphologic features are inadequate to definitively separate sebaceous lymphadenomas from lymphadenocarcinomas.