Unusual Location of a Cutaneous Granular Cell Tumor: A Case Report and Review of the Literature

Granular cell tumor (GCT), or Abrikossoff's tumor, is an uncommon neurogenic neoplasm originating from Schwann cells. While predominantly benign and frequently found in the head and neck, its clinical and radiological presentation can mimic more aggressive soft tissue sarcomas. We report the case of a 65-year-old female patient presenting with a firm, slow-growing mass in the right submammary fold. The biopsy revealed polygonal cells with granular, eosinophilic cytoplasm. Immunohistochemistry (IHC) showed diffuse S100 protein positivity and CD34 negativity, confirming a cutaneous GCT. The tumor exhibited infiltrative growth patterns with involved margins, perineural tracking and vascular invasion that defined an atypical tumor according to Fanburg-Smith criteria. A wide excision with 1 cm margins was made to achieve a complete resection with uneventful follow up. GCT is often known as a "great mimicker" due to its ability to simulate malignancies. Given the high local recurrence rate (20-40% for margin-positive or infiltrative lesions), GCTs necessitate wide-margin excision.