Signet-ring cell carcinoma of the breast.

Primary signet-ring cell carcinoma of the breast is a very rare tumor and is not recognized as an independent entity of the World Health Organization classification of breast tumor. Primary signet-ring cell carcinoma of the breast is usually considered as a variant of mucinous carcinoma or lobular carcinoma and usually originates from the lobular epithelium. A case of primary signet-ring cell carcinoma of the breast in a 68-year-old woman is presented. Histologically, the majority of neoplastic cells had an intracytoplasmic mucin collection. The histological presence of ductal carcinoma in situ, absence of lobular lesion and immunoreactivity for estrogen and progesterone receptors implicated the tumor cells arising from ductal epithelium. The papillary or organoid growth pattern is characteristic in this case. The patient underwent a modified radical mastectomy and was subsequently followed up for 6 months.