Hori's Nevus vs Melasma: Treating Deep Pigment

Hori's nevus — medically, acquired bilateral nevus of Ota-like macules (ABNOM) — is a pigmentation made of pigment cells sitting deep in the dermis. It usually appears as symmetrical greyish-brown or blue-brown patches on the cheeks and temples, often in adult Asian women, and is very commonly mistaken for melasma.

The distinction matters enormously, because the two are treated almost oppositely. Melasma is shallow-to-mixed and easily worsened by aggressive lasers; Hori's is deep and actually needs laser to reach and clear it. Getting the diagnosis right is the whole game.

The defining feature of Hori's nevus is depth. Its pigment cells sit in the dermis, well below the surface, which gives it that characteristic grey or blue-brown tone (deep pigment reads cooler through the skin). Topicals and gentle peels work at the surface, so they simply cannot reach it — which is why creams disappoint.

Pigment lasers, by contrast, can deliver energy to that depth and break the pigment up for the body to clear. This is the reverse of melasma, where reaching deep and hard is exactly what causes trouble.

They overlap in appearance and location, which is why they are confused — and sometimes they coexist. But several clues help: Hori's is often greyer/bluer, tends to appear later and stay stable, and does not respond to the creams that help melasma. Melasma is browner, fluctuates with sun and hormones, and worsens with aggressive treatment.

Because misdiagnosis leads to the wrong treatment intensity, a proper assessment (sometimes with skin imaging) is the safe way to tell them apart before treating.

Pigment-specific laser is the mainstay. Because the pigment is deep and dense, it takes a series of sessions spaced out over time to gradually break it down and let the body clear it. Improvement is cumulative, and results tend to hold well rather than relapse the way melasma does.

Sun protection still matters to protect the skin and avoid post-treatment pigmentation, and where melasma coexists, the plan has to balance treating the deep pigment without provoking the shallow melasma — a genuinely doctor-led balancing act.

If greyish-brown patches have resisted creams, or you have been treated for 'melasma' without success, it is worth being assessed for Hori's nevus. Getting the diagnosis right changes the entire approach — from cautious-and-topical to laser-led.

At DrPlus in Johor Bahru, pigmentation is assessed carefully to separate deep dermal pigment from melasma before any treatment.