Encyclopedia of Pathology

Living Edition
| Editors: J.H.J.M. van Krieken

Nevi, Intramucosal

  • Jacqueline E. van der WalEmail author
Living reference work entry
DOI: https://doi.org/10.1007/978-3-319-28845-1_744-1

Synonyms

Definition

Melanocytic nevi of the oral mucosa are benign tumors of melanocytes, the pigment-producing cells in the skin and juxtacutaneous mucous membranes, including the oral mucosa. Melanocytic nevi are much less common in the oral mucosa than on the skin (Buchner and Hansen 1987; Buchner et al. 2004; Müller 2010). The intramucosal nevus is the oral counterpart of the cutaneous dermal nevus.

In an intramucosal or subepithelial nevus, the (nests of) nevus cells are located within the underlying connective tissue and are often nonpigmented. They are usually small, 4–6 mm in greatest diameter, well-circumscribed macules or slightly raised papules.

Clinical Features

Incidence

Intramucosal nevi are the most common subtype (60–80%) of nevi.

Age

The age ranges from 3 to 87 years with a mean age for intramucosal nevi of 38 years.

Sex

A female preference has been reported (female to male ratio 1.5:1).

Site

The hard palate, buccal mucosa, and gingiva are the most common locations.

Treatment

No treatment is required for nevi. However, most adult-onset pigmented lesions are removed to rule out malignancy (malignant melanoma).

Outcome

After excision neither recurrences nor malignant transformation has been reported (Meleti et al. 2007).

Microscopy

Histologically, intramucosal nevi present as an unencapsulated proliferation of nests (thèques) of not atypical nevus cells (melanocytes) in the subepithelial connective tissue or both. The cells have small, uniform nuclei and a moderate amount of eosinophilic cytoplasm with distinct cell boundaries. The cells demonstrate a variable capacity to produce melanin, with pigment usually present in the superficial part of the lesion. The lesion is characterized by three zones of differentiation. The superficial cells are larger, epithelioid, and often pigmented with a tendency to cluster. Cells in the middle portion of the lesion are smaller and seldom pigmented. Cells at the base of the lesion are small or elongated and spindle shaped (Figs. 1 and 2).
Fig. 1

H & E stain of an intramucosal nevus, with nevus cells in the subepithelial connective tissue

Fig. 2

Detail of Fig. 1

Immunophenotype

No immunohistochemical stains are necessary for diagnosing an oral melanocytic nevus. However, nevus cells are positive for S100 and HMB-45 (Gazit and Daniels 1994).

Molecular Features

Cutaneous melanocytes frequently harbor oncogenic BRAF or less commonly NRAS or HRAS mutations. However, no molecular studies have been reported on oral melanocytic nevi.

Differential Diagnosis

References and Further Reading

  1. Buchner, A., & Hansen, L. S. (1987). Pigmented nevi of the oral mucosa: A clinicopathologic study of 36 new cases and review of 155 cases from the literature. Oral Surgery, Oral Medicine, and Oral Pathology, 63, 676–682.CrossRefPubMedGoogle Scholar
  2. Buchner, A., Merrell, P. W., & Carpenter, W. M. (2004). Relative frequency of solitary melanocytic lesions of the oral mucosa. Journal of Oral Pathology & Medicine, 33, 550–557.CrossRefGoogle Scholar
  3. Gazit, D., & Daniels, T. E. (1994). Oral melanocytic lesions: Differences in expression of HMB-45 and S-100 antigens in round and spindle cells of malignant and benign lesions. Journal of Oral Pathology & Medicine, 23, 60–64.CrossRefGoogle Scholar
  4. Meleti, M., Mooi, W. J., Casparie, M. K., & van der Waal, I. (2007). Melanocytic nevi of the oral mucosa – No evidence of increased risk for oral malignant melanoma: an analysis of 119 cases. Oral Oncology, 43, 976–981.CrossRefPubMedGoogle Scholar
  5. Müller, S. (2010). Melanin-associated pigmented lesions of the oral mucosa: Presentation, differential diagnosis, and treatment. Dermatologic Therapy, 23, 220–229.CrossRefPubMedGoogle Scholar

Copyright information

© Springer International Publishing AG 2018

Authors and Affiliations

  1. 1.Department of PathologyAntoni van Leeuwenhoek Hospital, The Netherlands Cancer InstituteAmsterdamThe Netherlands