April 2015 Case of the Month
42 year-old woman found to have a dense breast mass on mammography. The patient then had a wire-localized excisional biopsy of the lesion, with the resulting histopathology below. What is your diagnosis?
Low power reveals areas of densely fibrotic stroma and interspersed adipocytes distributed within.
Some areas of the lesion show vaguely keloid like appearance to the collagenous stroma.
High power examination of these "epithelioid" cells show relatively bland nuclear cytology and abundant pale cytoplasm.
Low power reveals areas of densely fibrotic stroma and interspersed adipocytes distributed within.
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April 2015 Case of the Month
Answer: Lymphocytic Mastopathy/Diabetic Mastopathy
A limited panel of immunohistochemical stains were performed to characterize the epithelioid cells and rule out an epithelial neoplasm. These cells were negative for CK AE1/AE3 and showed focal positivity for CD34 and desmin, thus supporting a myofibroblastic phenotype. Given the morphologic features of this lesion, a phone call to the surgeon to elicit more clinical history revealed that the patient had type I diabetes mellitus. Given that history and the triad of periglandular lymphocytes, keloid like collagenous fibrosis, and epithelioid myofibroblasts, this lesion is consistent with lymphocytic mastopathy/diabetic mastopathy. Although not entirely clear, this lesion is thought to represent an autoimmune process. Recurrences of these lesions have been reported.