Facial Dermal Melanocytosis

From the standpoint of age of onset, there is overlap between classical nevus of Ota and Hori's or Sun's nevus. The distribution of pigmentation is identical between nevus of Ota and Hori's nevi, although mostly unilateral in nevus of Ota. The histology of Hori's and Sun's nevi is identical to nevus of Ota. These late-onset dermal melanocytoses appearing on the face can be treated by Q-switched lasers, as is the case with nevus of Ota. Therefore, these dermal melanocytoses are included in the same disorder, which we propose calling facial dermal melanocytosis (FDM). They are more common than infantile onset cases and are frequently observed in Asian countries. In our study of patients who complained of acquired hypermelanosis appearing on the face, 12.2% were diagnosed as FDM. If “dark rings under the eyes” is included in this category, the incidence of FDM is very high. Adult onset FDM is frequently and persistently confused with the other commonly acquired hypermelanosis, suchas melasma, ephelides, and solar lentigines. Misdiagnosis induces malpractice, because FDM can be treated easily by Q?switched lasers. Therefore, FDM signify differential diagnosis from the other acquired hypermelanosis.