MON-136 Rare Cause of a Suspicious Breast Lump in a Diabetic Woman: Broaden Your Differentials!

Introduction: Diabetic mastopathy is a rare fibro-inflammatory breast lesion that characteristically presents in premenopausal women with long-standing type 1 diabetes mellitus with multiple microvascular complications. Here we describe a case of diabetic mastopathy to emphasize the close communication between physician, radiologist and pathologist needed to avoid unnecessary repeated interventions in this vulnerable population. Case Report: A 50 year old woman with long standing type 1 diabetes mellitus and end stage renal disease on hemodialysis was referred for screening mammography. Mammography revealed heterogenous breast with architectural distortion in right breast at the 12:00 position. USG also showed a large irregular hypoechoic mass with posterior acoustic shadowing, 5.3 x 1.9 x 2.0 cm at the 12:00 position. BI-RADS Category was 5, interpreted as highly suggestive of malignancy. Ultrasound-guided core needle biopsy was done which revealed lymphocytic ductitis, sclerosing lobulitis with non-proliferative fibrocystic changes. A diagnosis of diabetic mastopathy was made. Subsequent annual mammograms continued to demonstrate the above findings and awareness of this diagnosis has prevented her from undergoing repeated biopsies. Discussion: The pathogenesis is linked to an autoimmune response to abnormal extracellular matrix accumulation secondary to effects of hyperglycemia. It can result in palpable breast masses which are often described as firm, mobile and painless. The US features are generally suspicious for malignancy while mammography may show focal asymmetry. The posterior acoustical shadowing which is secondary to fibrosis is the hallmark as seen in our patient. Core biopsy is generally needed for initial pathological diagnosis but may yield non-diagnostic findings in many cases. The characteristic histopathological features include lymphocytic lobulitis, ductitis, B cell vasculitis and dense keloid-like fibrosis. The differential diagnosis includes inflammatory myofibroblastic tumor, granulomatous mastitis, sclerosing lipogranulomatous response or sclerosing lipogranuloma. Although the above mentioned histopathologic features can be encountered in nondiabetic breast biopsies, epithelioid fibroblasts appear to be unique to the diabetic condition. The correlations between imaging and pathology play an important role in the diagnostic process. While in some cases the pathologist may not be provided with a history of diabetes mellitus, the characteristic fibrosis, sclerosing lobulitis with perilobular and perivascular lymphocytic infiltrates provide clues for an accurate diagnosis. Timely and accurate diagnosis of this rare cause of a breast mass can hopefully help women avoid unnecessary repeat biopsies as well as surgical procedures.