A recent article published in Der Hautarzt discussed that nevus of Ota, nevus of Ito and nevus of Hori are special melanocytic nevi, which are slate-brown or blue or grey in color. These are pigmented disorders characterized by their heterotopic melanocytic dermal location and blue or brown unilateral, and sometimes, bilateral facial patch—in case of nevus of Ota, and in the supraclavicular, scapular and deltoid regions—in case of nevus of Ito. It is more common in patients with Asian and dark-skinned ethnic backgrounds. 

Histological features include – elongated, dendritic melanocytes, scattered mainly throughout the upper third of reticular dermis. An acquired variant – Horis nevus, has a more bilateral facial distribution, resembling melasma. 

The authors stated that dermal melanocytosis can also occur on other sites, for instance, inside the mouth. Although it’s a benign lesion, patients frequently seek therapy owing to the facial involvement. 

This article informed that quality-switched (QS) lasers are efficacious in treating these lesions, and the number of treatment sessions depends on the clinical improvement. However, post laser hypo- and hyperpigmentation are common side effects, especially in patients with darker skin.

Source: Der Hautarzt.2020 Dec;71(12):926-931. doi: 10.1007/s00105-020-04710-3.