Case report of a breast granular cell tumor in a young transgender man.

Introduction And Importance: Granular cell tumors (GCTs) can be diagnostically challenging due to their rarity, diverse anatomic locations, and clinical and radiologic similarities to other more common entities. GCTs involving the breast are rare and are most commonly encountered in premenopausal cisgender women. We report an unusual case of a breast GCT in a young transgender man.

Case Presentation: A 20-year-old transgender man who was on testosterone therapy for about 1 year presented with a painless, palpable mass in the right breast which radiologically resembled a lymph node. A fine needle aspiration showed morphology and immunohistochemistry consistent with a GCT. The tumor was excised by a mastectomy for therapeutic and gender-affirming purposes which confirmed the diagnosis of a breast GCT.

Clinical Discussion: Breast GCTs are most commonly found in cisgender women, however the mechanisms behind this relationship and whether transgender persons have an altered risk profile are not well understood. Breast GCTs are typically benign lesions with a low chance of recurrence following excision.

Conclusion: GCTs are rare and poorly understood entities which have not been previously documented in transgender patients and can resemble other benign or malignant lesions.