Nevus of Hori
Nevus of Hori, known medically as acquired bilateral nevus of Ota-like macules (ABNOM), is a benign, acquired dermal hyperpigmentation. It shows up as gray-brown, brown-black or blue-gray spots arranged symmetrically over both cheekbones, the temples, the sides of the nose, the forehead and the eyelids. It most often appears in Asian women between the ages of 20 and 40.
Although it is harmless to physical health, nevus of Hori can take a real toll on facial appearance. Because it is so often mistaken for melasma, freckles (ephelides) or sun spots (solar lentigines), many patients end up on the wrong treatment: overuse of acid peels, long courses of hydroquinone, or heat-based spot treatments that leave depressed scars, white patches of lost pigment and marked post-inflammatory hyperpigmentation (PIH).
Standard treatments fail mainly because the pigment cells (melanocytes) in nevus of Hori sit deep in the papillary and reticular dermis, a depth no topical product can reach. At Haute-Derma, we use a standardized protocol built around ultra-short-pulse 1064 nm picosecond laser, combined with care for the surrounding skin, to break down the dermal pigment without damaging the epidermis above it.
Pathogenesis and Cellular Mechanisms of Nevus of Hori
Nevus of Hori stems from melanocytes that are abnormally present in the dermis and later become active again. Three biological processes are involved:
- Incomplete Embryonic Migration: During fetal development, pigment-cell precursors (melanoblasts) travel from the neural crest toward the epidermis. In people who develop nevus of Hori, some of these cells stop short in the dermis and remain dormant.
- Reactivation by Hormones and Environmental Triggers: In adulthood, these dermal melanocytes can be switched on by estrogen and progesterone (a pattern often seen in pregnancy or with oral contraceptives), ultraviolet (UV) radiation, chronic inflammation or aging. They then start producing large melanosomes and release melanin that collects in the dermal connective tissue.
- The Tyndall Effect: Because the melanin lies deep in the papillary and reticular dermis, light passing through the overlying epidermis is scattered, with shorter wavelengths scattered more strongly. This is why the spots look characteristically gray-blue, blue-black or gray-brown, rather than the dark or light brown of pigment sitting in the superficial epidermis.
Telling Nevus of Hori Apart From Other Facial Pigment Disorders
| Nevus of Hori (ABNOM) | Nevus of Ota | Dermal / Mixed Melasma |
|---|---|---|
| Acquired (age 20–40) | Congenital or early onset (before age 20) | Acquired (age 20–50) |
| Discrete gray-brown or gray-blue spots, 1–5 mm | Broad, diffuse gray-blue to blue-black patches | Hazy patches or coalescing spots, brown to gray |
| Symmetric on both sides: cheekbones, temples, sides of the nose | Usually one-sided (unilateral), following the V1 and V2 trigeminal branches | Symmetric: cheeks, forehead, chin, upper lip |
| No involvement of the mucosa or the sclera of the eye | Involves the sclera and oral mucosa (> 50%) | No mucosal involvement |
| Papillary and reticular dermis | Deep dermis (full dermal thickness) | Epidermal, dermal or mixed |
| No response to topical creams | No response to topical creams | Partial response to hydroquinone and retinoids |
How We Examine, Use Dermoscopy and Grade Nevus of Hori at Haute-Derma
- Multi-Layer Pigment Analysis With VISIA Evolution
- We map the shape and depth of the spots under cross-polarized and UV light.
- This also picks up coexisting problems, such as epidermal melasma or vascular lesions alongside nevus of Hori.
- Detailed Dermoscopy
- Dermoscopic features of nevus of Hori: gray-blue or gray-brown speckled or cloud-like dots (a speckled/globular slate-blue pattern) scattered irregularly in the dermis, with no relation to the ridges and furrows of the epidermis.
- Wood's Lamp Test
- Under Wood's light (365 nm), nevus of Hori spots do not become more prominent and may even look fainter, because the pigment lies deep in the dermis. This is a reliable way to confirm that the lesion is dermal.
- Clinical Grading and Assessment of Coexisting Conditions
- Isolated type: dermal nevus of Hori spots only, on otherwise healthy skin.
- Complex mixed type: nevus of Hori overlapping with melasma, or on skin that is sensitive or shows dilated blood vessels.
Our 1064 nm Picosecond Laser Protocol at Haute-Derma
Since the pigment in nevus of Hori is entirely dermal, peels and ablative resurfacing lasers do not work and tend to cause complications. At Haute-Derma, we use the 1064 nm picosecond laser as our gold-standard treatment.
- Deep Penetration: Epidermal melanin absorbs 1064 nm light less than it absorbs 532 nm or 755 nm, so more of the beam reaches the reticular dermis where the nevus cells lie.
- Photoacoustic Breakdown: Ultra-short picosecond pulses generate a shock wave that shatters dermal pigment cells and melanosomes into very fine, dust-like particles.
- Natural Clearance via the Lymphatic System: Macrophages engulf these melanin fragments and gradually carry them away through the lymphatics, leaving dermal collagen and blood vessels intact.
Our Three-Phase Treatment Plan:
- Preparing the Skin and Treating Superficial Coexisting Lesions: If nevus of Hori sits on top of melasma, we first bring the melasma under control and repair the basement membrane with gentle laser toning, tranexamic acid electroporation and restorative skincare, so the melasma does not flare.
- Deep-Acting 1064 nm Picosecond Laser: We treat each spot at 1064 nm with a 3–4 mm spot size. The desired immediate response is slight raising of the spot or light gray-white whitening (mild frosting), with no bleeding. A course runs 4–8 sessions spaced 6–8 weeks apart, giving macrophages time to clear the pigment.
- Recovery and PIH Control: Right after the laser, we apply an intensive soothing mask and perform cryo-electroporation with 5% tranexamic acid plus repair peptides. Patients are also shown how to use a broad-spectrum PA++++ / PPD > 16 sunscreen.
