Melanoacantoma oral: estudo clinicopatológico e imunoistoquímico

Abstract

Oral melanoacanthoma is a rare, benign, black-brown pigmented lesion, characterized by its sudden appearance and rapid growth. The pathogenesis of oral melanoacanthoma remains uncertain, but most authors suggest a reactive process The aim of the present study is to present a case series of oral melanoacanthoma, exploring its clinical, histopathological, and immunohistochemical features. Nine cases of oral melanoacanthoma were retrieved. Clinical data were collected from biopsy charts. Hematoxylin-eosin slides were reviewed for histopathological analysis. Immunohistochemistry for TRP2, CD3, and CD20 was done. The mean age was 47.1 years (± 19.0), with a female to male ratio of 2:1. Lesion mean size was 11.0 mm (± 9.3). Clinical presentation was mostly of macular lesions (77.8%), with brown or black coloration (77.8%). Multiple sites were affected in 3 cases, followed by lower lip and soft palate (2 each). The evolution time ranged from 1 to 96 months. Lesions commonly showed epithelial acanthosis (66.7%), spongiosis (55.6%), and exocytosis (77.8%). Melanin was detected in the lamina propria of 8 cases. Seven cases showed inflammatory infiltrate in the lamina propria, from which all showed lymphocytes. Plasma cells were visualized in 4 cases, while eosinophils, neutrophils, and mast cells were rarely seen. CD3-positive cells predominate over the CD20-positive cells in five of the seven cases that presented inflammation. TRP2 positive melanocytes were identified in the basal and spinous layer of all cases, and in the superficial layer of three cases. Oral melanoacanthoma occurs mainly in female patients, and a wide age range may be affected. Lesions usually arise as brown/black macules, and the lips are the most common site. T-lymphocytes and TRP2-positive melanocytes were consistently found and should participate in the pathogenesis of oral melanoacanthoma.