Acquired Bilateral Nevus of ota-like Macules with Mucosal Involvement: A New Variant of Hori's Nevus.

Acquired bilateral nevus of Ota-like macules (ABNOM) or Hori's nevus, a rare form of acquired dermal melanocytoses, presents as bilateral facial blue-gray macules without ocular or mucosal involvement. This condition is mostly found in women of Asian descent and usually appears in the fourth or fifth decade of life. Pathogenesis is unknown, though few theories have been proposed. Effective treatment has been found to be achieved with pigment-specific lasers. Herein, we report a case of Hori's nevus with mucosal involvement. A 42-year-old male patient, presented to us with blue-gray discoloration on either side of his face, both eyes, and in the mouth since the age of one year. Histopathological examination showed clusters and singly dispersed pigmented melanocytes within the upper and mid-dermis regions. Special staining of melanocytes using Masson-Fontana stain was positive. Diagnosis of Hori's nevus was made by correlating clinical and histopathological findings. Patient was informed of his treatment options, but refused treatment. A similar case of Hori's nevus with mucosal involvement has not been reported so far.