Definition: Pigmented cellular nevi are benign malformations of melanocytes and “nevus cells,” common in the skin and rare in the oral mucosa.
Etiology: Developmental. Melanocytes and nevus cells of neural crest origin.
Clinical features: Based on histological criteria, oral pigmented nevi are classified into four types: intramucosal, junctional, compound, and blue. Clinically, the lesion appears as an asymptomatic, well-demarcated, flat or slightly elevated, brown, black, or blue spot or plaque (Fig. 90). The lesion is usually solitary, with a diameter of less than 1 cm. The palate, gingiva, buccal mucosa, and lips are the sites of predilection.
Laboratory tests: Histopathological examination.
Differential diagnosis: Ephelis, lentigo, melanoma, amalgam tattoo.
Treatment: Usually, no treatment is required. Conservative surgical excision is carried out in some cases.