Carcinome micropapillaire invasif: une tumeur mammaire rare et aggressive

Invasive micropapillary carcinoma of the breast is a rare and distinct histological variant of breast cancers, accounting for less than 3% of all breast carcinomas. It is characterized by a pejorative prognosis due to heavy lymph node involvement and the presence of numerous vascular and lymphatic emboli. We here report the case of a 63-year-old woman presenting with left mastodynia evolving for two months. Physical examination revealed breast asymmetry with skin retraction and multiple suspected lymph nodes in the left axilla. Mammography objectified a spiculated mass in the left breast classified as ACR5. Breast microbiopsy showed invasive micropapillary carcinoma. The patient underwent left Patey’s mastectomy with ipsilateral axillary dissection. Macroscopically, the tumor was grayish-white with spiculated margins located at the union of the two external quadrants and measuring 13 x 8 cm (Panel A). Histological examination of the surgical specimen revealed invasive carcinomatous proliferation arranged in clusters, nests, micropapillae, morules and glands with reversed polarity within a fibro-inflammatory stroma retracted around the carcinomatous structures (Panel B, C). Histoprognostic grading (SBR grade) modified according to ELSTON and ELLIS was 3. Several peritumoral vascular emboli were detected as well as lymph nodes metastases 20N+/20N. Immunohistochemistry using EMA showed reversed polarity (Figure D). Molecular classification of the tumor was luminal B. The postoperative course was simple. The patient underwent adjuvant chemoradiotherapy. Currently, the patient is systematically monitored on an outpatient basis.