Trial of a Rare Diagnosis in a Core Needle Biopsy of Breast

Mucinous carcinoma is a rare, special subtype of breast carcinoma associated with a good prognosis. It often presents a confusing appearance with a benign process. For all these reasons, differential diagnosis could be challenging.

Eighty years-old woman with a soft, lobulated, and well circumscribed mass at the left breast mimicking a benign process. Pathological examination of a core needle biopsy showed pure mucinous carcinoma.

It is a disease of elderly patient, over 60 years, and usually occurs in postmenopausal women. It accounts for only 2% of total breast carcinomas. On pathologic analysis, to be defined as pure mucinous carcinoma, a carcinoma must be made up of at least 90% intracellular or extracellular mucin.

Examination of core biopsy material should be done carefully respecting this criteria to confirm the diagnosis of this rare entity and eliminate differential diagnosis.