Introduction/Background Mucinous carcinoma of the breast (also called´ colloid carcinoma) is characterized by the presence of extracellular mucin and constitutes 1% to 4% of all breast cancers. The objective of the study was to specify the epidemiological, clinical, biological, therapeutic as well as prognostic features of this rare form of breast tumor.

Methodology Retrospective study of 10 patients treated and followed in our department over a period of 06 years between 2017 and 2023.

Results The average age of our patients was 41.2 years and the average delay of consultation was 18 months. Only one patient was menopausal. 7 patients had a palpable breast mass, the average size of the tumor was 4cm. Two patients had unilateral galactorrhagia without palpable nodule. Only one patient had a bilateral tumor. The tumors were classified as T0 in two cases, T1 in two cases, T2 in four cases and T4b in two cases. Only one patient had sternal bone metastases. Two patients received neoadjuvant chemotherapy. Five patients had a mastectomy with axillary curage and only one had a bilateral lumpectomy with bilateral axillary curage. The majority of tumors were histologically low grade; hormone receptors were expressed in 5 cases, Her2 negative in all cases, while triple negative status was described in 2 cases. Nodes were invaded in only one case.

Conclusion Mucinous carcinoma of the breast is a rare form of breast malignancy. Our results agree with those of the literature and confirm the favorable prognosis of this histological form.

Disclosures Mucinous carcinoma of the breast is a rare histological entity, accounting for 7% of all malignant tumors of the breast after the age of 75 and 1% before the age of 35. The most frequent revealing sign is autopalpation of a breast nodule, bilaterality is rare and mutifocality is exceptional. Node invasion is correlated with tumor size. Histologically, a distinction is made between pure mucinous carcinoma with a good prognosis and mixed carcinoma. There is no particular therapeutic consensus for colloid carcinoma, the indications for surgery, chemotherapy, radiotherapy and hormonal therapy are similar to those for other cancers.