Solitary circumscribed neuroma (palisaded encapsulated neuroma) of the oral mucosa

Background. The solitary circumscribed neuroma or "Palisaded Encapsulated Neuroma" is an infrequent benign tumor of the skin of adults, often localised on the face, around the orifices. The involvement of the oral mucosa or of the vermilion border of the lips is rare. Case reports. In our 5 cases, a small painless and more or less protruding nodule had been present for years on the mucosa of the hard palate (50 year-old man, 43 year-old woman), the soft palate (63 year-old woman), the vermilion border of the lower lip (48 year-old woman), and the gingiva (26 year-old man). The non specific clinical aspect did not permit a correct diagnosis. Discussion. Histologically, the solitary circumscribed neuroma is formed by a proliferation of Schwann cells arranged in interlacing bundles, featuring one or several well-limited nodules, sometimes surrounded by a thin capsule. At first sight, this aspect might sometimes mimic schwannoma or neurofibroma. The lesion is interspersed with a variable amount of axons. An association with neurofibromatosis or MEN syndrome type Ilb has never been found. Even after incomplete excision the solitary circumscribed neuroma does not recur, a fact supporting a reactive rather than a neoplastic origin.