Pediatric Granular Cell Tumor of the Digital Nerve: A Case Report and Literature Review.

Introduction: Granular cell tumors (GCTs) are rare soft tissue neoplasms thought to originate from Schwann cells of the peripheral nervous system. These tumors predominantly occur in the head and neck regions. Instances of GCTs affecting peripheral nerves of the upper extremity, particularly in the hand, are exceptionally rare. Methods: A 9-year-old girl presented with a rapidly growing mass on the left index finger. Ultrasound and magnetic resonance imaging revealed a mass encasing the neurovascular bundle extending to the dermal surface. Biopsy confirmed the presence of a GCT. Intraoperatively, the tumor, which was embedded within the radial nerve and adherent to the tendon sheath, was excised. Nerve reconstruction was performed with a posterior antebrachial cutaneous nerve graft. Results: Histopathology showed pleomorphic polygonal cells with granular cytoplasm and mild nuclear atypia. Immunohistochemical staining was positive for S100, CD68, SOX10, NKI/C3, inhibin, and TFE3, confirming the diagnosis of a benign GCT. The tumor was successfully excised with clear margins. Conclusions: Here we present the 5th documented case of GCT originating from the digital nerve and first-ever case treated with excision and posterior antebrachial cutaneous nerve graft reconstruction. The successful use of a nerve graft in this case underscores the value in preserving sensory function after tumor excision. Long-term follow-up is essential to monitor for recurrence and ensure favorable outcomes.