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

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.

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.

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.