Mucinous carcinoma of breast with psammomatous calcification: report of a rare case with extensive axillary metastases.

Pure mucinous carcinoma of the breast accounts for about 2% of all breast carcinomas and is associated with a favourable prognosis due to its lower nuclear grade and infrequent axillary or hematogenous metastases. Micropapillary variant of mucinous carcinoma breast has recently received attention as a unique form of invasive carcinoma of the breast exhibiting dual differentiation towards mucinous as well as micropapillary. The characteristic features for labeling a tumor as mucinous micropapillary carcinoma are micropapillary pattern, nuclear pleomorphism, hobnail cells and psammoma bodies in addition to the predominant mucinous component. Micropapillary mucinous carcinoma (MUMPC) when compared to pure mucinous carcinoma tends to have a higher nuclear grade, axillary lymph node metastases, lymphovascular invasion and overexpression of Her 2, p53 and Ki-67, thereby displaying an aggressive clinical behaviour. We present a rare case of micropapillary mucinous carcinoma to highlight the fact that this being a unique and rare variant of mucinous carcinoma should be recognized and reported as a separate category by the pathologists owing to its aggressive clinical behaviour and its influence on the nature of therapy.