Pure primary signet ring cell carcinoma breast: A rare cytological diagnosis.

Signet ring cell carcinoma (SRCC) of the breast is a rare tumor and it is classified by World Health Organization in 2003 classification under 'mucin producing carcinomas'. Pure form of SRCC breast is an extremely rare entity and very few cases have been reported in literature so far. We present a case of pure primary SRCC of the breast in a 70-year-old female, which was diagnosed on fine needle aspiration cytology. Cytological features generally show cellular smears with tumor cells showing eccentrically placed large, irregular nuclei showing indentations at places with cytoplasmic vacuoles. This case is being presented in view of its characteristic cytological features and its rarity.