Mediastinal Granular Cell Tumor in a 16-Year-Old Boy: A Surgical and Pathologic Perspective.

Granular cell tumor is a benign tumor of likely neural or neuroectodermal origin that occurs most commonly in the subcutaneous tissues of the trunk, breast, and extremities of adults. Congenital gingival lesions comprise the majority of the pediatric granular cell tumors. Granular cell tumors are generally small and asymptomatic, and while 1 in 10 patients has multiple tumors, recurrence and malignancy are very rare. Mediastinal granular cell tumors have been reported, most occurring in young adult or middle-aged women. We present a case of a 16-year-old asymptomatic boy with a large mediastinal granular cell tumor incidentally identified after a motor vehicle accident, and we review the intraoperative, microscopic, and ultrastructural features of this tumor. Both the patient's age and anatomical location are unusual for this tumor, which presented technical and diagnostic challenges to the patient care team.