Vulval Melanosis: Symptoms, Causes, and UK Management Guide

Vulval melanosis, also known as vulvar lentiginosis, is a benign (non-cancerous) condition where flat, dark brown or black patches appear on the vulval skin. These patches are caused by an increase in the production of melanin, the pigment that gives skin its colour, rather than an increase in the number of pigment-producing cells.

In the UK, it is estimated that around 1 in 10 women may have some form of vulval pigmentation. These marks are often discovered during routine cervical screening or self-examination. While the appearance of new dark spots can be alarming, vulval melanosis is not infectious, not related to hygiene, and does not lead to cancer. However, because it can visually mimic more serious conditions, understanding how to monitor these spots is essential for women's health.

Vulval melanosis typically presents as one or more flat patches of skin that are darker than the surrounding area. Key characteristics include:

• Colour: Patches are usually dark brown, black, or tan.
• Shape: The edges are often irregular or blurred, which can sometimes cause concern as this is also a feature of melanoma.
• Size: Patches can range from a few millimetres to several centimetres in diameter.
• Texture: The skin remains smooth and flat; there is no raised lump, scaling, or crusting.
• Lack of Sensation: Unlike thrush or dermatitis, vulval melanosis does not cause itching, pain, or burning.

These patches can appear on the labia majora, labia minora, or around the vaginal opening. They may stay the same size for years or slowly enlarge over time.

The exact cause of vulval melanosis remains unknown. Unlike skin cancer on other parts of the body, it is not linked to ultraviolet (UV) light exposure from the sun. Research suggests a possible hormonal influence, as the patches sometimes appear or darken during pregnancy or while taking hormonal contraceptives.

It is most commonly diagnosed in women between the ages of 20 and 50. There is no evidence to suggest that vulval melanosis is hereditary, although some women may be more prone to hyperpigmentation generally. It is important to note that this condition is entirely distinct from sexually transmitted infections (STIs) and is not caused by sexual activity.

The primary concern for both patients and clinicians in the UK is distinguishing benign melanosis from vulval melanoma, a rare but serious form of skin cancer. While melanosis is common and harmless, melanoma accounts for only about 1% of all melanomas in women.

According to British Association of Dermatologists guidelines, a biopsy may be recommended if a lesion shows specific 'ABCDE' warning signs: Asymmetry, irregular Borders, multiple Colours, large Diameter, or Evolving (changing) features. Because vulval melanosis can naturally have irregular borders and multiple shades of brown, a professional assessment is the only way to ensure peace of mind.

The Role of Biopsy

If a GP or online doctor is uncertain about the nature of a pigmented patch, they will refer you to a gynaecologist or dermatologist. A small skin sample (biopsy) may be taken under local anaesthetic. This is a quick procedure that confirms whether the cells are benign melanosis or something that requires further treatment.

If you notice a new dark spot or patch on your vulva, it is natural to feel anxious. Speaking to an online doctor is a discreet and efficient way to start your clinical journey. During a video consultation, you can discuss your symptoms, how long the patch has been there, and whether you have noticed any changes.

A UK-based GP can provide:

• Initial Assessment: A review of your medical history and a description of the lesion.
• Referral Advice: If the doctor feels the patch needs a physical examination or biopsy, they can guide you on the next steps within the NHS or private sector.
• Reassurance: If the symptoms are consistent with benign melanosis, the doctor can help explain the condition and what to look out for in the future.
• Mental Health Support: Addressing health anxiety related to new skin changes.

Seeking help early is always recommended. While most vulval spots are harmless, early detection is vital for the small number that are not.

In the UK, the standard diagnostic pathway involves a visual examination by a healthcare professional, often using a dermatoscope (a specialized magnifying tool). If the lesion is confirmed as vulval melanosis, no treatment is necessary. The condition does not pose a health risk, and the patches do not need to be removed.

Laser therapy or surgical excision is generally discouraged for benign melanosis as it can lead to scarring and discomfort without any medical benefit. The focus of management is 'watchful waiting'—monitoring the area for any significant changes in appearance. Many women find that once they have a formal diagnosis, the anxiety surrounding the spots resolves.