Infiltrating syringomatous adenoma of the nipple.

Infiltrating syringomatous adenoma of the nipple is a rare, benign, locally invasive tumor with recurrence potential, showing sweat duct differentiation. It can clinically, radiologically and pathologically mimic cancer. Histopathologically, it must be distinguished from florid papillomatosis, adenosquamous carcinoma, adenoid cystic carcinoma and sclerosing syringomatous carcinoma. A 44-year-old woman presented with pain on the right nipple for 7 days. On physical exam there was an irregular nodule on nipple area with edema. The skin was intact. The ultrasound showed a hypoechoic irregular nodule measuring 7.5 mm in the nipple area. The mammography was unspecific. The lesion was surgically removed and histopathologically, the tumor was composed of ducts and tubules lined with a double-layered epithelial cells. The lining cells were small, cuboidal with a central nuclei and eosinophilic nuclei. The stroma was dense with lymphocytes and plasma cells, and compressed many of the ducts that contained a comma or tadpole-shape, giving an impression of a syringoma. Some ducts were slightly dilated with squamous metaplasia. Some of these cysts were connected with the overlying epidermis. Mitotic figures were rare and no pleomorfism or hyperchromasia was observed. At the periphery, the ducts invaded muscular fibers of the nipple. The surgical margins were free of neoplastic involvement. Patient has no signs of progression of disease in 1 year of follow-up.