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Oral Melanoacanthoma — MFDS Part 1 MCQ

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HardOral PathologyOral MelanoacanthomaMFDS Part 1

A 34-year-old patient presents with a rapidly enlarging, asymptomatic, irregular brown-black macule on the buccal mucosa. Because the clinical appearance cannot reliably exclude melanoma, an incisional biopsy is performed. Which histopathological finding most strongly supports a diagnosis of oral melanoacanthoma?

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Correct answer: D — Acanthotic or spongiotic epithelium containing numerous benign dendritic melanocytes extending through the spinous layers

The correct answer is D. Oral melanoacanthoma is a benign, usually reactive pigmented mucosal lesion that may enlarge rapidly and clinically resemble melanoma. Its characteristic microscopic feature is an acanthotic, sometimes spongiotic, epithelium containing prominent benign dendritic melanocytes distributed among keratinocytes through multiple epithelial layers. Option A describes oral malignant melanoma, with cytological atypia, pagetoid spread and invasion. Option B is characteristic of Kaposi sarcoma or another vascular spindle-cell lesion. Option E indicates granulomatous inflammation, as may occur in orofacial granulomatosis or sarcoidosis. Option C describes suprabasal acantholysis, classically associated with pemphigus vulgaris. Because clinical appearances overlap with melanoma, suspicious or rapidly changing oral pigmentation requires biopsy rather than diagnosis by appearance alone.

Reference: Abed SS, Fitzpatrick SG, Bhattacharyya I, Islam MN, Cohen DM. Oral Melanoacanthoma: Case Series of 33 Cases and Review of the Literature. Head and Neck Pathology. 2023;17(2):364-370. https://pubmed.ncbi.nlm.nih.gov/36478543/