Acquired Bilateral Nevus of Ota-Like Macules: A Case Report.

ABSTRACT

Facial melanoses (FM) present complex diagnostic and therapeutic challenges, particularly in the setting of dermal melanocytoses (DM). We present a case that illustrates these challenges as it does not fit within existing classification frameworks. Initially considered as Ota nevus, characterized by blue or dark pigmentation and scleral involvement, histopathological findings suggested acquired bilateral nevus of Ota-like macules (ABNOM). While ABNOM, more common in Asians, rarely affects the sclera or children, recent studies indicate that it may be underdiagnosed in these groups. Differential diagnosis ruled out other FM causes due to mucosal involvement. Correct classification is essential for epidemiological accuracy and treatment decisions, especially given varying responses to Q-switched laser therapy and melanoma risks associated with Ota nevus and ABNOM. While the pathogenesis remains unclear, a two-hit model involving shared melanoma mutations in melanocytes has been proposed and warrants further molecular study.