Cytologic Features of Hidradenoma in Fine Needle Aspiration Biopsies

Objective To review the cytologic features of hidradenoma to describe criteria that may aid in identification of these tumors at the time of aspiration and allow for a more specific diagnosis than the umbrella term of benign skin adnexal tumor. Study Design Three patients aged 10-23 years presented with mass lesions in the region of the head. Fine needle aspiration (FNA) of these lesions showed the presence of benign skin adnexal tumors. Subsequent histology showed the presence of hidradenomas. A retrospective analysis of the cytology was performed. Results The following cytomorphologic findings are consistent with the diagnosis ofhidradenoma: a cystic component to the aspirate as represented by amorphous background material with or without foam cells and epithelial duct-like cells and tubular structures. In addition, a biphasic cytoplasmic staining pattern with both eosinophilic and clear to basophilic cells may be seen with the Papanicolaou stain in hidradenomas. Conclusion Knowledge of the cytologic features of hidradenoma will allow for correct management of the patient and prevent misdiagnosis as a malignant tumor.