Blue Naevus (Blue Mole) – Consultant Diagnosis & Monitoring in London

Understanding blue naevus

A blue naevus (also spelled “blue nevus”) is a benign mole that appears blue because the pigment is located deeper in the dermis rather than close to the surface. Light scattering through the skin (the “Tyndall effect”) makes brown pigment look blue, similar to how the sky appears blue. Most blue naevi are small, solitary, and long‑standing. They commonly occur on the hands, forearms, feet, face, or buttocks, but can appear anywhere. Many people first notice one in their teens or 20s; others have one from childhood and it simply stays the same for decades.

For the vast majority of people, a blue naevus is nothing to worry about. However, new blue‑coloured lesions or existing lesions that change deserve an expert review to make sure nothing else is going on. At Skinhorizon, our dermatology team uses careful history‑taking, dermoscopy (a specialised skin microscope), and where appropriate, removal with histology to give you clear answers and peace of mind.

Causes and mechanism

Blue naevi are made up of melanocytes—pigment‑producing cells—that have settled deeper in the dermis. When melanin is deeper in the skin, longer wavelengths of light are absorbed, and shorter blue wavelengths are reflected back to the eye, creating the characteristic blue hue. Unlike common moles (junctional or compound naevi) that lie at or near the surface, blue naevi do not usually show the typical brown network pattern seen on dermoscopy. Most are “common blue naevi”; a less frequent type called a “cellular blue naevus” is typically larger and firmer. Rare combined lesions have both a blue naevus component and a conventional mole in the same spot.

The exact trigger for a blue naevus is not fully understood. Some appear after minor trauma or irritation; others are present from early life. They are not caused by infection and are not contagious. Hormonal changes (for example, during puberty or pregnancy) may make pigment appear slightly darker, but rapid growth or major changes are not expected and should be assessed.

Who gets blue naevi?

Blue naevi can occur in any age group and any skin tone. They often appear in adolescents and young adults and may be noticed incidentally during a skin check. People with darker skin types may have lesions that look more slate‑grey or blue‑black. Having a blue naevus does not automatically put you at higher risk of skin cancer, though everyone should remain aware of new or changing lesions.

Recognising typical features

A typical blue naevus is a small (<1 cm), well‑defined, dome‑shaped papule with a uniform blue, blue‑grey, or blue‑black colour. The surface is usually smooth and not scaly; it does not ulcerate or bleed. Many patients describe it as a “steel‑blue bead” under the skin. When a lesion is larger, irregular, multi‑coloured, flat with a new blue hue, or associated with symptoms like bleeding, crusting, or pain, further evaluation—including possible removal—may be advised to exclude other conditions.

Diagnosis: clinical examination and when to biopsy

Diagnosis starts with a focused consultation: how long the lesion has been present, whether it has changed, any symptoms, and your personal and family skin history. Dermoscopy helps us see structures not visible to the naked eye; many blue naevi display uniform, structureless blue pigmentation without melanoma‑specific features. If the history or examination raises uncertainty—such as recent change, atypical size or shape, ulceration, or if the lesion appears in an unusual site—we may recommend complete excision so that a specialist pathologist can examine it under the microscope. Excision is both diagnostic and, if the lesion is benign, curative.

We also consider the broader picture. For example, a new blue‑grey lesion in someone with a history of melanoma elsewhere warrants particular care, as very rarely a deposit of melanoma can look blue. Your safety comes first; we will always explain why a biopsy or excision is (or isn’t) recommended in your case.

Management options for Blue Naevus

Many blue naevi require no active treatment and can simply be documented and observed. When removal is requested—because of diagnostic uncertainty, growth or irritation, or cosmetic preference—the most reliable approach is surgical excision under local anaesthetic. This removes the entire lesion and provides tissue for histology, giving a definitive answer. The scar is usually a thin line; our clinicians use meticulous techniques to minimise scarring and place incisions along relaxed skin tension lines where possible.

Selected small, flat lesions may be considered for pigment‑targeting lasers (for example, Q‑switched devices) when the diagnosis is clear and the goal is cosmetic lightening. However, because the pigment lies deep in the dermis, multiple sessions may be needed and lightening can be partial. Laser does not provide a histological diagnosis, so it is not appropriate when there is any diagnostic doubt. We will discuss the pros and cons for your individual lesion.

Aftercare and recovery

After a simple excision, you can usually return to normal daily activities the same day. We advise keeping the dressing dry for 24–48 hours, then gentle cleansing and application of a thin layer of petrolatum‑based ointment until the wound heals. Stitches (if used) are typically removed in 7–14 days depending on the body site. Early scars appear pink, then gradually fade over several months. Silicone gel or sheets and strict sun protection can help scars settle more quickly. If laser treatment is chosen, expect brief pinpoint crusting and temporary darkening before lightening occurs; rigorous sun protection is essential during the healing phase.

Prevention and self‑care

There is no proven way to prevent a blue naevus from forming. However, sensible skin habits make monitoring easier: photograph the lesion with a date stamp for comparison, protect exposed skin with broad‑spectrum SPF 30–50+, and avoid unnecessary picking or trauma. Build the habit of a quick monthly skin check—looking for new lesions or notable changes—and seek review if anything looks different from your usual pattern. If you are unsure whether a change is meaningful, we are happy to assess and document it for you.

Special circumstances: children, pregnancy, and skin of colour

Blue naevi in children are usually stable and harmless. Because children grow, a proportionate increase in size over time can be normal; sudden changes or symptoms should still be checked. During pregnancy, hormones can deepen pigmentation, making a lesion look darker without it truly growing—nonetheless, new or changing lesions should be examined. In darker skin tones, the colour can appear blue‑black; careful dermoscopy and clinical context help differentiate benign from suspicious lesions. Our clinicians are experienced in assessing lesions across the full spectrum of skin types.

Setting expectations

Most blue naevi remain unchanged and never need treatment. If you choose removal, excision provides clarity and typically a very good cosmetic outcome, though any procedure will leave a scar. Laser can soften colour in selected cases but rarely removes pigmentation completely; multiple sessions may be required and recurrence or incomplete lightening is possible. We will help you weigh the cosmetic benefit against the likelihood of residual colour and the importance of a firm diagnosis.

Why choose Skinhorizon?

Skinhorizon combines consultant‑led assessment with modern diagnostic tools to give you a clear plan. We provide high‑quality advanced dermatology and aesthetic services with a focus on safety and natural‑looking results. Where treatment is needed, minor surgical procedures are performed under local anaesthetic with careful attention to scar placement and closure. All excised specimens are sent to accredited pathology for definitive reporting. If non‑surgical options are appropriate, we will explain realistic outcomes and aftercare so you can make an informed choice.

Your first visit — what to expect

1. Focused consultation: we review your concerns, timeline, and any changes you have noticed.
2. Skin examination and dermoscopy: close inspection with a handheld dermatoscope to assess pigment patterns and depth.
3. Documentation: clinical photography for your records and future comparison, if helpful.
4. Discussion of options: monitoring versus removal, with benefits, limitations, and likely cosmetic outcomes.
5. Procedure (if chosen): local anaesthetic excision or other agreed treatment, with clear aftercare instructions.
6. Follow‑up: review of healing and, where relevant, pathology results explained in plain language.

Reviewed by: Dr Mohammad Ghazavi, Consultant Dermatologist
Skinhorizon Clinic, 4 Clarendon Terrace, Maida Vale, London W9 1BZ
Last reviewed: 20 August 2025