Oral Melanoacanthoma: Case Series of 33 Cases and Review of the Literature

Oral melanoacanthoma (OM) is a rare, reactive, and benign proliferation of two cell types: keratinocytes and melanocytes. Biopsy is mandatory to not only confirm the diagnosis but also, rule out other entities, as clinical correlation simply, is not definitive.

We present a large series of OM with analysis of demographics, clinical appearance, histologic presentation, and review of the literature. To the best of our knowledge, this is the largest series of oral OM reported to date.

Following IRB approval, cases diagnosed as OM within the archives of the University of Florida Oral Pathology Biopsy Service (1998–2020) were included. Patient age, gender, location, clinical appearance, clinical impression, and duration of each lesion was collected.

A total of 33 cases were included with a mean age of 38.7 years (range of 5–73), and a female: male ratio of 2.6:1. The most common location in descending order was the buccal mucosa (n = 16, 48%), followed by palate (n = 11, 33%), tongue and labial mucosa (n = 2 each, 6%), maxillary and mandibular gingiva (n = 1 each, 3%). The lesions were most frequently brown/black in color, and most often described as macular. All cases were asymptomatic and reported duration was ranged from one week to twelve months. Clinical impression in descending order was pigmented macules (n = 15, 45%), melanosis (n = 4, 12%), nevus (n = 3, 9%), melanoma (n = 2, 6%), melanoacanthoma (n = 1, 3%), and racial pigmentation (n = 1, 3%). Ethnicity was only documented in only 6 out of 33 cases, of which 5 cases were African-American and one Caucasian. The majority of cases (n = 28, 84%) demonstrated hyperplastic/acanthotic surface epithelium with less common, atrophic (n = 4, 12.1%) or spongiotic epithelium (n = 2, 6.06%).

The demographics and clinical presentation of OM in our series was similar to previous findings but encompasses wider variability of histologic presentation. Awareness of OM in the clinical and histologic differential diagnosis of pigmented lesions should be reinforced as many patients are concerned for melanoma and clinicians are often unware of this condition.