S-100 Negative Granular Cell Tumor of Oral Cavity with Aggressive Clinical Behavior

Abstract

Abstract Introduction/Objective Granular cell tumors (GCTs) are neoplasms with neuroectodermal (Schwann cell) differentiation that is typically benign and cured by surgical excision. These tumors characteristically display strong expression of S-100 protein. Similar tumors without expression of S-100 protein are called “S-100 negative granular cell tumors.” The few reported cases of S-100 negative GCT in the oral cavity describe indolent clinical behavior. We report a case of a 49-year-old male with recurrent S-100 negative GCT in the oral cavity. Methods/Case Report The patient presented initially with a mass in the hard palate, which was resected and diagnosed as an S-100 negative GCT. One year later, the patient developed severe epistaxis and anemia (hemoglobin 7.2 g/dL). A large tumor of the hard palate was the source of bleeding. It was resected and diagnosed as recurrent S-100 negative GCT. Histologically, this tumor consists of small nests of epithelioid to spindled cells with moderately abundant granular eosinophilic cytoplasm, round central nuclei with vesicular chromatin and distinct eosinophilic nucleoli, and significant mitotic activity. The cells are immunoreactive for SOX10 and negative for S-100, melan-A, keratin AE1/AE3, p40, synaptophysin, smooth muscle actin, desmin, and myogenin. Results (if a Case Study enter NA) N/A Conclusion S-100 negative GCTs are rare, and only a few case reports describe their involvement in the oral cavity. We report this case because of its rarity and aggressive clinical behavior. Recognition of this entity and its potential for locally aggressive growth is important. Management of this tumor by complete excision seems advisable.