Polypoid S-100-negative granular cell tumor of the oral cavity: a case report and review of literature.

This is a report of a case of an S-100-negative polypoid granular cell tumor arising in the lower lip of a 4-year-old patient that may represent the entity primitive polypoid granular cell tumor. Unlike the usual granular cell tumors arising in the tongue or buccal mucosa, such lesions are not S-100 positive and can exhibit mitoses and cytologic atypia, features that may suggest a low-grade mesenchymal malignancy necessitating aggressive therapy. However, this is in fact a nonaggressive neoplasm that is not associated with significant morbidity and therefore should be treated with simple excision.