A 41-year-old woman presented with a lump above the right areola. She also complained of a burning and heavy sensation of the right breast of recent onset. On further history, the patient was an insulin-dependent diabetic of 35 years’ duration. She had no family history of breast disease. On examination, a palpable thickening above the right areola was detected. Bilateral mammography revealed dense fibro-glandular tissue, denser in the right retro-areolar region than the left, with right peri-areolar skin thickening. There was no discreet mass nor suspicious microcalcifications or axillary adenopathy. Ultrasound (US) demonstrated an ill-defined peri-areolar region of decreased echogenicity and posterior shadowing. Core biopsy under US guidance showed abundant thick collagen bands containing epitheloid fibroblasts and a stroma with small capillary-sized and larger muscularised blood vessls, some of which contained peri-vascular lymphocytic inflammatory cells. Small ductal elements and an occasional lobule showed a peri-ductal and a peri- and intra-lobular lymhocytic and plasma cell infiltrate. These features were in keeping with sclerosing lymphocytic mastitis, known also as diabetic mastopathy.