An uncommon case of T1b breast cancer with diabetic mastopathy in type II diabetes mellitus.

A 64-year-old postmenopausal female had been treated with insulin therapy for type 2 diabetes mellitus for 18 years, but her diabetes mellitus was not well controlled and she developed retinopathy. Her screening mammography showed abnormal findings, and thus she consulted a hospital. A physical examination showed her mammary glands to be hard on both sides and no palpable mass was observed. Mammography revealed an amorphous calcification in the middle outer portion of the left breast. Ultrasonography showed an irregular hypoechoic mass measuring about 11 mm in size in the upper outer portion of the left breast. Although a core-needle biopsy specimen of the hypoechoic mass showed hyalinizing fibrosis without any evidence of malignancy, a stereotactic guided vacuum-assisted biopsy was performed because magnetic resonance imaging revealed an enhanced area in the region of the amorphous calcification that could not be distinguished from breast cancer. The histological findings indicated noninvasive ductal carcinoma, and therefore a quardrantectomy with a sentinel lymph node biopsy was performed. The pathological diagnosis was invasive ductal carcinoma (0.7 × 0.3 cm) with a predominant intraductal component accompanying diabetic mastopathy. The sentinel lymph nodes demonstrated no metastasis. The surgical margin was positive for carcinoma and the patient later underwent a mastectomy. No malignant cells were observed in the specimen. The patient has so far experienced no recurrence after surgery.