Granular Cell Tumor Breast Masquerading as a Malignancy Cytologically: a Rare Case Presenting a Diagnostic Dilemma.

Granular cell tumor (GCT) also known as Abrikossoff's tumor is an uncommon soft tissue tumor of neurogenic origin. GCT of the breast accounts for < 0.1% of breast tumors and 6% of all reported cases of granular cell tumor. Although GCT is a benign tumor, malignant GCT can be seen in 1% v of the cases. GCT of the breast is diagnostically challenging as it can imitate carcinoma clinically and radiologically but need to be differentiated from breast malignancy since they have totally different approach in treatment and prognosis. GCT has a great ability to mimic a variety of lesions from benign histiocytic to malignant epithelial/mesenchymal lesions, thereby presenting a diagnostic challenge to the practicing cytopathologist. We report a case of GCT of breast cytologically masquerading as a malignancy in a 45-year-old female. Although, fine needle aspiration (FNA) is a first-line diagnostic tool, the present case reemphasizes the role of histopathology as the gold standard for a definite diagnosis clubbed with ancillary techniques like immunohistochemistry and special stains. © Indian Association of Surgical Oncology 2020.