Acquired Compound Melanocytic Nevus on the Palate of a Child: Report of a Case.

Background: Oral melanocytic nevi are relatively rare in comparison to their cutaneous counterparts. The aim of this manuscript is to present a case of acquired compound oral melanocytic nevi on the hard palatal mucosa of a child.

Methods: A 5-year-old female girl was referred for evaluation of a pigmented lesion on the hard palate. The lesion was asymptomatic and present for approximately 2 months. Oral clinical examination revealed a well-circumscribed brownish macule on the hard palatal mucosa, adjacent to the left first primary upper molar. Considering the recent onset of the lesion, biopsy was recommended, but the patient returned 3 years later, when increase in size with slight asymmetry and colour variation were noticed. An excisional biopsy was performed.

Results: Microscopic examination revealed nevus cells randomly distributed along the basal cell layer and organized into nests along the junctional area and within the papillary layer of lamina propria, while immunohistochemical evaluation showed positivity of nevus cells for SOX-10 and Melan-A. A final diagnosis of compound melanocytic nevi was rendered, and the patient was advised to attend regular follow-up appointments.

Conclusions: Although oral melanocytic nevi are rare in childhood, their potential development should not be overlooked. Acquired oral melanocytic nevi need to be differentiated from several other common (e.g. amalgam tattoo) and uncommon (e.g. melanoma) oral pigmented lesions, as well as from the more rare congenital oral melanocytic nevi. Oral melanocytic nevi with junctional activity (i.e. junctional, compound subtypes) appear to be more common in children, possibly reflecting an earlier developmental stage.