Introduction/Background Colloid or gelatinous carcinoma is a rare histological form, representing 1 to 6% of all breast cancers. It usually appears after 70 years. It is evoked in mammography before a limited opacity or micro-lobulated in an elderly woman. The well-circumscribed limits focus a priori on the pure type, while the ill-defined margins focus more on the mixed type.The majority of cases do not express HER-2 and have positive hormonal receptors. The prognosis is excellent.

The purpose of our work is to clarify the anatomical, immunohistochemical and evolutionary features of this particular entity.

Methodology We carried out a retrospective study of patients treated for colloid breast cancer at the Medical Oncology Department of the Tlemcen University Hospital Centre.

Results Ten patients were collected.

The average age is 55 years [38, 81]. The main reason for consultation is the discovery of a nodule at autopalpation. The average evolution time is 14 months [1.60]. The average size is 4.1 cm [2.10]. The right breast is most affected (7/10). The upper-outer quadrant is the most common seat (8/10). The majority of patients were diagnosed at a localized stage, classified as T2N0M0 in 7 patients. All of our patients received radical Patey surgical treatment.

The pathological study is in favor of a colloid carcinoma, grade III (3/10), with lymph node invasion (4/10), positive hormonal receptors (9/10), Her 2 negative (10/10). Adjuvant chemotherapy based on anthracycline (7/10) followed by Taxane (3/10), hormone therapy (9/10) and radiation therapy (5/10). Two patients received adjuvant hormone therapy alone.

After a median follow-up of 76 months, 9 patients are still followed in consultation.

Conclusion Colloid (mucinous) breast carcinoma is a rare variety, occurring mainly after menopause with a favorable prognosis in its pure form.

Disclosures our results are compatible with the theoretical data already published