Background: Hidradenoma papilliferum is a rare benign tumor of the vulva that occurs mainly in women in the skin of the anogenital region. Clinically it may mimic a carcinoma, so the correct cytologic interpretation of the tumor cells with subsequent careful histologic confirmation is essential for good management.
Case: A 44-year-old woman who had a history of hysterectomy 14 years earlier presented with a small, exophytic growth on the labia majora. Fine needle aspiration cytology and vulvar scraping of the lesion were reported as a malignant tumor, and the case was referred to our center for further management. Repeat vulvar smears showed mainly groups and clusters of benign-looking glandular cells and were interpreted as a benign tumor. Subsequent histology confirmed the diagnosis of hidradenoma papilliferum.
Conclusion: This case highlights the cytologic features of hidradenoma papilliferum on cytologic smears. The clinical presentation should not mislead the cytologic interpretation of the tumor cells.