Oral melanoacanthoma: a report of 10 cases, review of the literature, and immunohistochemical analysis for HMB-45 reactivity.

Oral melanoacanthoma (MA) is rare reactive mucosal lesion that, like cutaneous MA, demonstrates hyperplasia of spinous keratinocytes and melanocytes. Unlike MA of the skin, oral MA is unrelated to seborrheic keratosis. This series adds 10 cases to the limited number of previous reports of oral MA. The clinicopathologic features of the cases in this series are generally consistent with those previously reported in the literature; that is, although documented in various intraoral locations in patients of differing ethnicity, oral melanoacanthoma most often presents as an enlarging flat or slightly raised area of hyperpigmentation on the buccal mucosa of adult black women. The current series provides evidence of occurrence over a wider age range (5-77 years) than previously reported. Additionally, the reactivity of oral melanoacanthoma to HMB-45 was investigated. Strong HMB-45 reactivity was present in all cases, thus demonstrating its limited utility in distinguishing oral MA from malignant melanoma.