Endocrine Abstracts

Objective: Diabetic mastopathy (DMP) is an uncommon fibrous disease of the breast, most commonly found in premenopausal women with type 1 diabetes exposed to long-standing insulin therapy. Often mimicking breast cancer clinically and on imaging, this condition poses a diagnostic challenge requiring pathological confirmation.

Case presentation: A 68-year-old woman with type 1 DM and a family history of breast cancer in paternal aunt had an abnormal screening mammogram showing a lobular nodular density in the subareolar region deep to the nipple measuring atleast 2.5 cm in the left breast. Ultra Sound (US) showed a hypoechoic, heterogenous mass 2 cm from the nipple, measuring 41×13×46 mm with relatively circumscribed margins, demonstrating some internal blood flow on Doppler. Lymph nodes were normal. Patient underwent US-guided biopsy. Pathology showed hyalinized stromal fibrosis and chronic mastitis. Within a short period of time, patient presented with a painless palpable area in the right breast. Mammography and US of right breast showed a very dense tissue in the palpable area of concern, corresponding to heterogeneous, slightly hypoechoic mass with relatively circumscribed margins measuring 38×18×65 mm with internal vascularity. It had a very similar appearance to the area that was biopsied on the left breast. Given the bilaterality and history of diabetes, a preliminary diagnosis of bilateral diabetic mastopathy (DMP) was made. A decision was made to follow up annually with regular mammography. Later, patient developed retraction in the skin and nipple areolar complex in both breasts. Mammogram and US of both breasts revealed large densities that were relatively stable, however the skin changes prompted repeat biopsies. Thickened tissue on both breasts was excised and sent for pathology revealing features consistent with DMP.

Discussion: Patients with DMP clinically present with painless, irregular, hard, unilateral or bilateral breast masses. It is rare as it represents 0.6% to 13% of benign lesions observed in woman with type 1 diabetes. The pathogenesis is not fully understood but many theories involving the effects of sustained hyperglycemia and glycosylated end products on the connective tissues of the breast have been proposed. Malignant transformation has not been described.

Conclusion: This case underlines the importance of considering diabetic mastopathy in the differential diagnoses when evaluating breast lesions in women with diabetes. Recognizing the presentation of this rare condition can help avoid unnecessary surgical intervention.