Clear cell and eosinophilic oncocytomas of salivary gland: cytological variants or parallels?

Oncocytomas are uncommon tumors of the salivary gland. They have an abundance of mitochondria, which is manifested as granular eosinophilic cytoplasm by light microscopy. On histological sections, presence of cytoplasmic glycogen and/or fixation artifact can impart cytoplasmic clearing, and oncocytomas with a predominance of clear cytoplasm are labeled clear cell oncocytomas. Two forms of oncocytoma, eosinophilic and clear cell, have been described in the surgical pathology literature. The purpose of this manuscript is to conduct a comparative cytological assessment to ascertain parallels and differences between the two variants.