Solitary mucosal neuroma of the gingiva without multiple endocrine neoplasia type 2B: a rare case report and literature review

Mucosal neuroma (MN) is a benign neural tumor of peripheral nerves histologically characterized by irregular tortuous bundles of nerve cells with prominent perineurium that lie scattered throughout the submucosa. The tumor is usually associated with the multiple endocrine neoplasia type 2B (MEN 2B) but rarely occurs without the other components of MEN 2B. A 29-year-old woman presented to our outpatient department with an upper anterior teeth gingiva painless mass for 2-year. Intraoral examination revealed a small, tough, basal wide, well-defined mass in the labial gingival papilla between maxillary central incisor. Excisional biopsy showed that it was characterized by nerve bundles in various sizes surrounded by normal connective tissue in the submucosa under HE staining; Immunohistochemically, the mass showed strongly positive staining of S-100 protein, NSE, NF and weakly positive of EMA. The Laboratory examination and ultrasonography showed no signs of MEN 2B. In the first and second 6 months of follow-up, there was no evidence of recurrence and other components of MEN 2B. The patient was asymptomatic and she is still being followed up every 6 months. Based on these features, the lesion was finally diagnosed as a solitary gingival MN. In summary, this study showed a rare solitary MN in the gingiva papilla without MEN 2B that has not been reported yet. The histopathological evaluation can be helpful in the differential diagnosis of MN. It is hoped that a greater understanding of solitary MN without MEN 2B in the oral cavity will avoid potential misdiagnosis, and contribute to determining the correct management, which appears to be complete surgical excision with close follow-up for recurrence and other components of MEN 2B surveillance.