A case of palisaded encapsulated neuroma arising in the lower lip

Abstract

Palisaded encapsulated neuroma (PEN), defined by Reed et al. in 1972, is a benign nerve sheath tumor with characteristic clinical and histological features. Clinically, the lesion is a solitary, firm, asymptomatic nodule; histopathologically, it is a well-circumscribed, partially or completely encapsulated tumor. The tumor cells are composed of interlacing fascicles of spindle cells. Nuclear palisading is found on occasion, but Verocay bodies are unremarkable. Axons are also found in the fascicles. In European countries there have been many reports of PEN by dermatologists, but PEN arising in the oral mucosa is rare. In Japan there has been no reported case of PEN arising in the oral mucosa, although several cases involving the skin have been described by dermatologists. In this article, we present a case of PEN arising in the lower lip mucosa. A 36-year-old man visited our clinic because of a mass of the lower lip. We suspected a mucous cyst the basis of the clinical course and other findings, and the mass was removed under local anesthesia. The pathological diagnosis of the specimen was PEN. There was no sign of recurrence 8 months after surgery.