Multifocal melanoacanthoma of the gingiva and hard palate

Gingival melanoacanthoma is an uncommon reactive lesion, typically appearing as a solitary pigmented macule. This article reports a previously undescribed case of multifocal melanoacanthoma affecting the maxillary and mandibular gingiva and the hard palate. A literature review of melanoacanthoma of the gingiva is also provided.

An otherwise healthy 60-year-old white female sought care for a periodic dental prophylaxis. The intraoral examination was remarkable for numerous painless, brown macular lesions in all four gingival quadrants and on the hard palate (eight on the gingiva and six on the palate). The lesions ranged in size from 2 to 4 mm. The patient had only been aware of one of these lesions, estimating its existence to be <1-year duration. The unusual and widespread presentation of these lesions warranted biopsy.

On microscopy, all surgical specimens revealed an acanthotic population of epithelium, with dendritic melanocytes distributed throughout, and numerous melanophages contained in the connective tissue. The dendritic melanocytes were immunoreactive for HMB-45 and S-100. Ultrastructural studies confirmed the presence of keratinocytes and dendritic melanocytes containing melanosomes. A 5.5-month follow-up recall disclosed six new pigmented lesions (four on the gingiva and two on the hard palate), clinically identical to the previously discerned melanoacanthomas. There has been no recurrence of any of the biopsied lesions.

Gingival melanoacanthomas may present as a solitary lesion or involve multiple sites. Pigmented gingival lesions of recent origin and without etiologic factors should undergo histopathologic review. A conservative biopsy for gingival melanoacanthoma may be sufficient for lesion identity and definitive treatment.