Oral Melanoacanthoma: A series of 33 cases and Review of the Literature

Abstract

<h3>Background</h3> Oral Melanoacanthoma (OM) is an unusual, likely reactive heavily pigmented, benign epithelial proliferation. OM often grows rapidly mimicking melanoma and leading to anxiety for both the patient and the clinician. We present a large series of OM including demographics, description of clinical appearance and characteristics, histology, and literature review. To the best of our knowledge, this is the largest series of OM reported to date. <h3>Materials and Methods</h3> Following IRB approval, OM cases from the University of Florida Oral Pathology Biopsy Service archives (1998-2020) were included. Demographics and clinical features were collected and slides were reviewed. <h3>Results</h3> 33 cases were included with a mean age of 38 years, female: male ratio of 2.6:1. The most common location was buccal mucosa (n = 16, 48.48%), followed by palate (n = 11, 33.33%), tongue and labial mucosa (n = 2 each, 6.06%), maxillary and mandibular gingiva (n = 1 each, 3.03%). Most lesions are dark black/brown, and often described as macular in nature. Duration ranged from one week to twelve months, and all cases were asymptomatic. The clinical impression in the majority of cases were that of a benign melanotic lesion. Ethnicity was only documented in 6/33 cases, of which five cases were African American and one was Caucasian. Histomorphologically, majority of cases (n=27, 81.8%) were hyperplastic/acanthotic, while atrophic epithelium cases were (n=4, 12.1%) and less commonly, spongiotic epithelium cases were (n=2, 6.06%). <h3>Conclusion</h3> The findings of this study are consistent with those in the literature concerning demographics and clinical presentation. Histologically, presence of dendritic melanocytes extending into the spinous cell layer along with acanthosis of the spinous cell layer is diagnostic for OM when combined with the clinical presentation. However, it is important to add cases of OM to the literature so clinicians can be more aware of this lesion.