In a period from 1980 to 1995, we experienced 67 cases of mucinous carcinoma (3.2%) out of 2, 801 primary breast carcinomas. These 67 cases were subjected to a study of clinical features and prognosis. There were 43 pure and 24 mixed types. Mean age of the patients was 54.1±14.2 years. TNM classification almost resulted in Stage I and Stage II but one patient of pure type and one patient of mixed type were in Stage IV. Only two patients (5%) of pure type mucinous carcinoma showed lymph node metastasis. Two patients with pure type mucinous carcinoma experienced recurrence to the lung, but they are still alive, as of 11 years 2 months and 4 years 11 months after the recurrence, respectively.
We suggest that if pure type mucinous carcinoma is exactly diagnosed, the operation without lymphadenectomy may be permitted.