Oral melanoacanthoma: a case report and review of the literature

Abstract

Introduction: Oral melanoacanthoma is a rare, benign pigmented lesion characterized clinically by the sudden appearance and rapid growth of a macular brown-black lesion and histologically by acanthosis of the superficial epithelium and proliferation of dendritic melanocytes.

Case presentation: We present a case report of oral melanoacanthoma in a 24-year-old Asian Indian man. He presented with an intra-oral brown macular lesion on the left buccal mucosa with a duration of one and a half months. Microscopic examination revealed acanthosis of stratified squamous surface epithelium and dendritic melanocytes diffusely distributed in the epithelium; the Masson-Fontana silver impregnation technique was used to demonstrate the dendritic melanocytes. Based on the history, clinical features and histological presentation, the lesion was diagnosed as melanoacanthoma.

Conclusion: This is the first reported instance of oral melanoacanthoma in the Indian sub-continent. This report details the course of the lesion from diagnosis to its resolution. Melanoacanthoma must be differentiated from other intra-oral pigmented lesions and biopsy may be required to rule out melanoma.

Figure 1

Brownish-black macular lesion on left buccal mucosa adjacent to molar teeth with Class V glass ionomer cement restorations (arrows).

Figure 2

Hematoxylin and eosin stained sections (A, B and C) revealed stratified squamous non-keratinized epithelium exhibiting acanthosis and numerous dendritic melanocytes throughout the entire thickness of the epithelium; Masson-Fontana (M-F) special stain reveals numerous melanocytes.

Figure 3

Follow-up of lesion after 1 week (A), after 2 weeks (B) and complete resolution after 2 months (C).