Pure signet ring cell carcinoma of the breast: a rare entity.

Signet ring cell carcinoma (SRCC) is defined as carcinoma composed of epithelial cells with intracytoplasmic mucin that causes peripheral displacement of the nucleus, creating a crescent-shaped morphology. It can arise in many organs; however, pure primary SRCC of the breast is very rare. The WHO classification of tumours placed SRCC of the breast under mucin-producing carcinomas; however, nowadays, it is no longer regarded as a histological variant of invasive carcinoma. To date, only few cases have been reported in the literature. This report presents a woman in her 70s with primary pure SRCC of the breast. The patient underwent right lumpectomy with sentinel lymph node dissection and was proposed adjuvant chemotherapy followed by radiotherapy and hormonal treatment. She had no disease relapse until today. The histological features and treatment approach of this rare entity are debated in light of relevant literature.