Melanocytic Nevi
Moles (melanocytic nevi) are the most common benign skin growths. They form from a localized proliferation of pigment cells (melanocytes) that have become nevus cells, sitting at the base of the epidermis, in the dermis, or in both. Although most moles are entirely benign, certain types (such as dysplastic or atypical nevi) carry a risk of progression or serve as an early warning marker for cutaneous melanoma. Telling apart a benign mole, a high-risk mole and an early melanoma is one of the core skills in dermatology and dermatopathology.
At Haute-Derma, we take a comprehensive approach to managing moles: high-resolution digital dermoscopy, total body photography for mole mapping, rigorous histological diagnosis, and medically safe cosmetic techniques that remove moles effectively while preserving the appearance of your skin.
Clinical Features and Pathology in Depth
How Moles Form and Their Histological Types
Moles arise from acquired growth-promoting gene mutations (mainly BRAF V600E, less often NRAS). These trigger an initial burst of melanocyte growth, which then switches itself off through a process called oncogene-induced senescence.
Based on where the clusters of nevus cells (nevus nests) sit under the microscope, melanocytic nevi fall into three main types:
| Histological type | Microscopic location | Typical clinical appearance |
|---|---|---|
| Junctional nevus | Nevus nests confined to the base of the epidermis, just above the basement membrane. | Flat, well-defined, dark brown or black, with normal skin markings preserved. Common in children and teenagers. |
| Compound nevus | Nevus nests in both the epidermis and the upper dermis. | Slightly raised, smooth papule, light to dark brown, with a clear border. |
| Intradermal nevus | Nevus nests located entirely in the dermis; the overlying epidermis is normal. | Dome-shaped or stalked (pedunculated), flesh-pink or light brown, sometimes with a hair in the center. Common in adults. |
Special Types and Melanoma Risk
- Dysplastic (atypical) nevus:
- Clinical: larger than 5 mm, irregular border, uneven color (a mix of brown, black, pink and red) and a fuzzy edge, often with a "fried-egg" look.
- Microscopic: atypical melanocytes at the junction growing in horizontal bands, papillary dermal fibroplasia and a lymphocytic infiltrate.
- Significance: the strongest independent risk factor for melanoma. People with five or more dysplastic nevi have about a tenfold higher risk of melanoma.
- Congenital melanocytic nevus (CMN):
- Present at birth or appearing within the first 2 years of life. Classified by projected adult size: small (< 1.5 cm), medium (1.5–20 cm), large (20–40 cm) and giant (> 40 cm).
- Giant CMN carries a 2–5% lifetime risk of developing melanoma.
- Halo nevus (Sutton nevus):
- A central mole surrounded by a round or oval ring of white, depigmented skin.
- The halo results from an autoimmune T-cell response against the central nevus cells. Careful dermoscopy is needed to rule out a melanoma that is driving the immune reaction.
- Blue nevus:
- A firm, raised blue-black or blue-gray papule. Its color comes from spindle-shaped melanocytes deep in the dermis, which scatter light and produce a bluish tint (the Tyndall effect).
Differential Diagnosis and Immunohistochemistry (IHC)
| Condition | Distinguishing microscopic and clinical features | IHC markers |
|---|---|---|
| Benign mole (melanocytic nevus) | Uniform nevus nests that mature from top to bottom (cells become smaller deeper in the dermis), with no abnormal mitoses. | S100 (+); SOX10 (+); Melan-A (+); very low Ki-67 (< 1–2%) at the base; diffuse p16 expression. |
| Melanoma | Large atypical melanocytes, loss of maturation with depth, abnormal mitoses in the dermis, and pagetoid cells climbing into the upper epidermis. | S100 (+); SOX10 (+); HMB-45 (+) in the deep dermis (loss of maturation); high Ki-67 (> 10–30%); loss of p16 (-). |
| Pigmented seborrheic keratosis | Proliferation of basaloid epidermal cells with horn pseudocysts and an intact basement membrane; not of melanocytic origin. | S100 (-); SOX10 (-); cytokeratin (+). |
| Vascular lesions (cherry angioma / glomangioma) | Vascular proliferation of dilated capillaries, dark red to purple, fading under glass pressure (diascopy). | CD31 (+); CD34 (+); S100 (-). |
Our Approach to Treating Moles
Haute-Derma manages melanocytic nevi according to two guiding principles: medical safety and the best possible cosmetic result.
- ABCDE screening and dermoscopy for every mole: every mole is examined with dermoscopy to rule out signs of malignancy before any removal or cosmetic treatment is planned.
- Mandatory biopsy when anything looks suspicious: we never laser or electrocauterize a mole with atypical features or unusual color without a confirmed pathology result.
- Treatment tailored to the histological type: we choose the technique that matches the depth of the lesion (ablative CO2 laser, picosecond laser, or surgical excision with cosmetic closure).
- Protecting appearance and preventing scars: micrometer-precise ablation combined with a scar-prevention plan (for depressed or hypertrophic scars) and post-procedure LED light therapy to support healing.
How We Diagnose and Manage Moles at Haute-Derma
To avoid missing an early melanoma and to choose the right treatment, Haute-Derma follows a four-step process:
- Clinical examination and ABCDE assessment:
- A (Asymmetry): one half does not match the other.
- B (Border): ragged, notched or jagged edges.
- C (Color): uneven coloring (black, brown, pink, gray).
- D (Diameter): larger than 6 mm.
- E (Evolving): rapid change in size, shape or color, or new symptoms such as itching, pain or bleeding.
- High-resolution dermoscopy and mole mapping: we assess the pigment network, dots and globules, blue-gray veil and vascular patterns, and use whole-body digital photography to track changes in each mole over time.
- Excisional biopsy: any mole with suspicious dermoscopic features is removed whole with a 1–2 mm safety margin.
- Pathology confirmation and treatment planning: IHC results (S100, Ki-67, HMB-45) confirm that the lesion is benign before any cosmetic treatment goes ahead.
How Moles Are Treated and Removed at Haute-Derma
Mole treatment at Haute-Derma is tailored to the histological depth of the lesion and the goal of treatment:
- Ultra-pulse CO2 laser ablation:
- Indications: small (< 3–4 mm) junctional or superficial compound nevi that look clearly benign on dermoscopy.
- Technique: layer-by-layer ablation in micron steps with precise depth control, sparing the deep dermis to prevent a depressed scar.
- Surgical excision with cosmetic closure:
- Indications: large intradermal nevi, raised dome-shaped moles, atypical nevi, or other deep lesions.
- Technique: an elliptical incision along the natural skin tension lines (Langer's lines), gentle dissection and intradermal closure with ultra-fine sutures (7-0 to 8-0) to make the scar as inconspicuous as possible.
- PicoSure / PicoWay laser:
- Indications: breaking up residual superficial melanin after laser ablation, or treating flat, light-gray moles.
- Aftercare and recovery:
- A healing cream containing epidermal growth factor (EGF), yellow/red LED light to reduce swelling, broad-spectrum sunscreen and silicone gel patches to help prevent scarring.
