Diagnosis of papillary hidradenoma of the vulva by fine needle aspiration cytology

A case of papillary hidradenoma of the vulva is reported. In this case, histologic identification could be made by fine needle aspiration cytology. The smear showed three types of cellular pattern. The most numerous were cuboidal cells with round nuclei and scant cytoplasms. These cells were usually arranged in a sheet-like pattern or in slight aggregation. The nuclear chromatin pattern was finely granular and the nucleoli were inconspicuous. The second type of cells appeared in small groups with eccentric nuclei and intracytoplasmic vacuoles. These findings were thought to be degeneration features of the first type of cells. The third cellular type also appeared in a sheet-like pattern with round nuclei and abundant, foamy cytoplasms. The intercellular borders were clear. These cells were thought to be originated from apocrine metaplasia.