Oral pigmentation in McCune-Albright syndrome.

IMPORTANCE: The differential diagnosis for oral lentigines includes several syndromes with important associated systemic findings. McCune-Albright syndrome (MAS), a mosaic condition associated with café au lait pigmentation, is not typically considered a mucosal lentiginosis syndrome. The clinical phenotype of MAS is variable because of mosaicism, but oral pigmentation developing in mid-childhood to early adulthood should be recognized as a clinical feature of MAS. OBSERVATIONS: We present 4 patients with MAS who developed oral mucosal pigmentation during childhood or early adulthood. All patients had other characteristic findings of MAS including hyperfunctioning endocrinopathies, polyostotic fibrous dysplasia, and café au lait pigmentation. CONCLUSIONS AND RELEVANCE: Oral pigmentation is an underrecognized finding in MAS and presents later in development compared with the other mucosal lentiginosis syndromes. The diagnosis of MAS is most commonly a clinical diagnosis because mutational analysis is challenging in mosaic conditions. Expanding the cutaneous phenotype to include oral pigmentation further characterizes the clinical findings in this mosaic condition, broadens the differential diagnosis of syndromes with oral pigmentation, and in some cases may aid in earlier diagnosis of MAS.