Syringomatous adenoma of the nipple: report of a case.

We report herein a rare case of syringomatous adenoma (SA) of the nipple. Only 22 cases of SA of the nipple have been documented in the world literature, and to the best of our knowledge this is the first case to be reported in Japan. The patient was a 68-year-old woman who presented with a painful mass in the right subareolar region of over 15 years' duration. Clinical examination including needle biopsy indicated a high possibility of carcinoma; however, the final histopathological diagnosis after mastectomy proved to be SA. SA is a benign locally infiltrating neoplasm of the nipple which shares many clinicopathological features with adenoma of the nipple. Both lesions sometimes show deceptive clinicopathological findings, causing then to be easily confused with carcinomas. However, SA can be distinguished by its unique histological appearance resembling sweat duct, or syringomatous, tumors and locally infiltrating growth, which is probably responsible for its misleading clinical findings and higher rate of recurrence. Surgeons should be aware of the possibility of diagnosing this extremely rare tumor, and the appropriate treatment.