Lymphocytic mastopathy mimicking carcinoma in a non–insulin-dependent diabetic: a case report

BACKGROUND: Lymphocytic mastopathy (also known as diabetic mastopathy, fibrotic mastopathy, or sclerosing lymphocytic lobulitis) is a rare benign fibroinflammatory breast disease that clinically and radiologically mimics breast carcinoma. It is most commonly associated with long-standing diabetes mellitus and autoimmune disorders. CASE PRESENTATION: We report the case of a 63-year-old woman with a 6-month history of a gradually enlarging, painless right breast lump. The patient was a known type 2 diabetic for 15 years on oral hypoglycaemic agents. Mammography and ultrasonography revealed an ill-defined hypoechoic lesion with marked posterior acoustic shadowing (BIRADS IV). Core needle biopsy was inconclusive. Excision biopsy demonstrated dense keloid-like fibrosis with periductal and perilobular lymphocytic infiltration without atypia, consistent with lymphocytic mastopathy. CONCLUSION: Awareness of lymphocytic mastopathy is essential to prevent misdiagnosis as malignancy and avoid unwarranted surgical interventions. Although rare in non-insulin dependent diabetics, this condition should be included in the differential diagnosis of breast lump that mimic carcinoma on clinical examination and imaging.