Spectrum of Cytological Findings in Idiopathic Granulomatous Mastitis With Clinical and Radiological Correlation: A Case Series From a North Indian Tertiary Center

Background Granulomatous mastitis is a rare, uncommon chronic inflammatory condition of the breast. The condition is a well-known mimicker of malignancy, both clinically and radiographically. Diagnostic dilemmas arise frequently in such cases, which delay the treatment. In the present study, we studied the cytomorphological features in cases of granulomatous mastitis diagnosed by fine needle aspiration cytology (FNAC) to attribute the clinical and radiological findings to each case. Methods A total of 13 cases with cytological diagnoses of granulomatous mastitis were reviewed and studied. Fine needle aspiration was performed on these patients, and smears were examined. In this study, the cytomorphological features were studied in depth and correlated with clinical and radiological findings. Ziehl-Neelsen stain and/or Truenat were performed in all 13 cases. Results Clinical examination revealed a lump in the breast in all the patients and a lump with pus discharge in two patients. Ultrasonographic examination suggested an inflammatory pathology in most of the cases. The smear examination showed diverse cytomorphological features, ranging from epithelioid cell granuloma to a vague collection of histiocytes, multinucleated giant cells, neutrophils, plasma cells, and a few lymphocytes. In four cases, there was prominent emperipolesis of neutrophils. Additionally, granulomatous mastitis was diagnosed in accessory axillary breasts in one of the cases. Based on cytomorphological features and after excluding commonly encountered granulomatous infective pathology, a diagnosis of granulomatous mastitis was made. In addition, the cytological diagnosis rests on finding histiocytes with neutrophils, giant cells, and epithelioid cell granulomas with or without necrosis and excluding other common differential diagnoses like tuberculosis, fungal infection, and Rosai-Dorfman disease. Conclusion It is important to keep a possibility of granulomatous mastitis in women presenting with painful nodular breast lumps. Aggressive management of other specific etiological causes of granulomatous mastitis can be avoided with an accurate cytological diagnosis of idiopathic granulomatous mastitis.