Idiopathic granulomatous lobular mastitis: A rare entity with diagnostic dilemma on fine needle aspiration

Abstract

Idiopathic granulomatous lobular mastitis (IGLM) is an uncommon and rare chronic inflammatory breast disease. The exact etiology is not known. Although various etiologies have been implicated, autoimmunity is favored and widely accepted. In countries with a high prevalence of tuberculosis, the diagnosis of IGLM is often challenging. Clinical presentation is quite variable. Ultrasonography and mammography findings lack specificity. Fine-needle aspiration (FNA) cytology features of idiopathic granulomatous mastitis (IGM) have been described in few reports, but they are still debatable. We report the case of a 36-year-old female with a hard lump in the left breast. Aspiration cytology smears showed many well-formed epithelioid granulomas and few scattered epithelioid cells. The background showed numerous polymorphonuclear leukocytes with few reactive lymphoid cells and foreign-body giant cells. There was no necrosis. Acid-fast bacilli (AFB) and fungal stains did not show AFB and fungal hyphae. A diagnosis of IGM was suspected on aspiration cytology. Histopathology examination confirmed the diagnosis. To conclude, though tuberculosis is highly prevalent in India, if breast FNA smears show epithelioid granulomas with numerous polymorphonuclear leukocytes with no necrosis or AFB, IGLM must be suspected.