Garrett Fiscus, Naomi Wiens, Brynn Wolff and Yanping Li
Granular cell tumor (GCT) is a rare benign soft tissue neoplasm of neural origin occurring virtually any body site, breast localization accounting for between 5% and 15% of all cases. Clinically and radiologically, GCTs display similar signs of malignancy with carcinoma, hindering the ability of a confident diagnosis. GCTs show a distinctive histological pattern of granular eosinophilic cytoplasm with S100 positivity.
We report the case of a 67-year-old woman who presented with a painful palpable mass in her left axillary tail for over 30 years. Mammography and ultrasound revealed a 15-mm, ill-defined hypoechoic area with shadowing and vascularity within her left axillary tail. Excisional biopsy was performed and postoperative histological examination with immunohistochemical staining confirmed the diagnosis of a granular cell tumor.
This case is of clinical interest due to the atypical examination findings of location and chronicity, in addition to the rarity of GCT within the axillary tail of the breast. Proper knowledge is needed for a broad differential for breast tumors.