Dermal Pigment · Staged Laser · CityLink Mall
Hori's naevus, also called ABNOM, is grey-blue speckling over both cheekbones, caused by pigment cells that sit deep in the dermis. This page explains how it is told apart from melasma, why creams leave it unchanged, and why Dr Sin Yong stages laser slowly, when it is chosen, because darkening after treatment is common.
In most brown marks, the pigment-making cells (melanocytes) sit at the base of the epidermis, the outer layer of skin. In Hori's naevus they lie lower, in the dermis. Hori described the condition in 1984, and its longer name, acquired bilateral naevus of Ota-like macules (ABNOM), says what it looks like: marks resembling naevus of Ota, on both sides, arriving in adult life.
Onset is usually in the twenties to forties, and most people affected are women with East or Southeast Asian heritage.
Types
Hori's naevus forms speckled, separate spots, placed evenly over both cheekbones and sometimes on the temples, forehead, sides of the nose and upper eyelids. Their tone stays grey or bluish, and a day in the sun does not make them noticeably darker. The whites of the eyes and the inside of the mouth are not involved. How it compares with other facial pigment is set out in pigmentation types.
Dr SY examines the cheeks in daylight, under a Wood's lamp and through a dermatoscope. Under the lamp, surface pigment stands out while dermal pigment barely changes. Through the dermatoscope, dermal pigment shows a diffuse blue-grey pattern; surface pigment, a brown network.
The Decision
Lightening creams such as hydroquinone, azelaic acid, tranexamic acid, retinoids and vitamin C act on pigment made in the epidermis, or on how quickly surface cells shed. Hori's naevus lies below the basement membrane, beyond their reach, and is not carried off as skin renews. Facials and peels also act only at the surface, and the harsher ones can leave new brown marks.
The order of care. The diagnosis is confirmed first, and any melasma identified, because heat can darken it. Sun protection comes next and, where melasma is present, topical control. Only then does laser begin, conservatively and in stages, with the gap between visits set by how your skin responded rather than by a calendar. A small test area may come first where the reaction is hard to predict.
When to wait. Laser is put off after a recent tan or sunburn, while the cheeks are inflamed or infected, in pregnancy, and while you take medicines that make skin sensitive to light. If melasma on the same cheek is not yet under control, that comes first.
When to look further. A one-sided patch reaching the white of the eye suggests naevus of Ota, and an eye assessment comes before any laser. Any one spot that looks different, because it is new, irregular in outline or changing, is examined to rule out another cause. No laser at all is always one of the options.
At Atelier
Dermal pigment needs a short-pulse laser that breaks pigment into fragments while little heat spreads around it. In the published literature, 1064 nm Nd:YAG, Q-switched nanosecond or picosecond, is the mainstay, because it passes through surface melanin with less absorption. Shorter 532 nm light is absorbed mainly near the surface, which makes it a tool for superficial marks rather than for Hori's naevus.
At Atelier, the dermal spots are treated with a picosecond laser on the DEKA TORO platform, in staged, conservative sessions. Melasma on the same cheek is managed first, on its own plan; see melasma.
Hori's naevus usually needs several sessions over a year or more, and the spots can look darker for a while after each one. Dr SY goes through this before the first session. Dr Sin Yong holds a Key Opinion Leader appointment with DEKA.
Safety
The main risk is post-inflammatory hyperpigmentation (PIH), new brown marks that follow inflammation. It is common with this condition, and the risk is higher with higher energies, with sessions repeated too soon, with sun on freshly treated skin, and in Fitzpatrick III to V skin. It generally fades, helped by time and strict sun protection; see post-inflammatory hyperpigmentation.
Laser over unrecognised melasma can make it flare; a published report describes melasma appearing after 1064 nm treatment of ABNOM. Less common problems include pale spots, redness that lingers, blisters or crusts, and a smaller improvement than expected.
In the weeks after a session, contact the clinic if you see blistering or thick crusting, if pain is getting worse, or if the skin darkens markedly. For problems after laser elsewhere, see complication care.
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