Granulomatous lobular mastitis: Difficulty of diagnosis

We report a case of a rare inflammatory disease, granulomatous lobular mastitis. Two weeks prior to admission the patient, a 43 year-old woman, (gravida 1, para 1) had noticed a left breast mass associated with tenderness. Palpation, gross inspection, and clinical examination, as well as the rapid growth of the mass lesion led us to believe that it was highly suspicious of malignant neoplasm. Mammography, ultrasonography, and computed tomography did not differentiate it from a malignant neoplasm. Aspiration cytology revealed an inflammatory lesion with a few clusters of epithelial cells it was diagnosed as borderline malignancy(class III) by a prudent pathologist, and thus mastectomy was performed. However, the final histological diagnosis was granulomatous lobular mastitis with no evidence of malignancy. As the clinical manifestations of granulomatous mastitis are similar to those of mammary carcinoma and, as it is an inflammatory lesion of uncertain etiology and pathogenesis, it has often been mistaken clinically for carcinoma and treated as such. Our review of the literature indicated that granulomatous mastitis most often occurs in young patients with a history of childbirth or oral contraceptive usage. Recurrence was documented in 38% of patients, and, accordingly long-term follow-up by aspiration cytology, complete resection, and adequate drug treatment with corticosteroids are recommended.