Idiopathic Granulomatous Mastitis: A Diagnostic and Imaging Challenge Mimicking Breast Carcinoma – A Retrospective Analysis of 20 Cases.

Abstract

Background: Idiopathic granulomatous mastitis (IGM) is a rare, benign chronic inflammatory breast disease that predominantly affects women of reproductive age. Its etiology remains elusive, although autoimmune mechanisms are suspected. Due to overlapping clinical and radiological features with breast carcinoma, IGM presents a diagnostic dilemma that often leads to misdiagnosis and unnecessary interventions. Histopathology remains the gold standard for diagnosis.

 Methods: We conducted a retrospective study of 20 histopathologically confirmed cases of IGM between June 2023 to May 2025. Clinical presentation, imaging characteristics, histological findings, treatment modalities, and outcomes were reviewed and analyzed.

 Results: The majority of patients (n = 17, 85%) presented with a unilateral palpable breast lump, with 12 (60%) reporting associated pain. Ultrasound was performed in all patients, revealing irregular, heterogeneous hypoechoic lesions with ill-defined margins and tentacle-like extensions in 16 cases (80%). Mammographic findings were nonspecific. Core needle biopsy confirmed the diagnosis in all cases. Histology showed non-necrotizing lobulocentric granulomas with Langhans-type giant cells in all patients. Treatment approaches included corticosteroids (n = 12), surgical excision (n = 4), and observation (n = 4). No progression to malignancy was noted during the follow-up period of 6–24 months.

 Conclusion: IGM remains a diagnostic challenge due to its clinical and radiological resemblance to breast cancer. Early histopathological confirmation is crucial to avoid unnecessary surgery. A multidisciplinary approach involving radiologists, pathologists, and surgeons is essential for accurate diagnosis and effective management.