Background A 57-year old woman had only unilateral milky dischardge of the right breast. Clinical and mammography findings were normal. Case presentation Cytological diagnosis of intraductal papilloma was established which was galactographically confitmed and patient underwent to surgery. Ductulolobular segmentectomy was made. Histopathologically beside intraductal papilloma numerous single dispread malignant "signet ring" cells in the fibrous retromammilary stroma were found. Imunohistochemically findings were: cytokeratin 8 positive, ER H-score 80, PR H-score 50, HER-2/neu negative. Diagnosis of "signet ring" cell lobular invasive carcinoma was made, followed by mastectomy, axillary limphadectomy and contra lateral breast biopsy. Conclusion Residual tumor were found only in the breast tissue, while axillary lymph nodes and contra lateral breast biopsy were negative. Patient underwent to oncology therapy.