Vulvar melanoma typically appears as a dark brown or black spot on the vulva, often with irregular borders and uneven coloring. It accounts for 5% to 10% of all vulvar cancers, making it the second most common type after squamous cell carcinoma. Because the vulva isn’t an area most people examine closely or regularly, these lesions are often found late, which makes knowing what to look for especially important.
Color, Shape, and Size
Most vulvar melanomas are pigmented, meaning they contain visible color. The most common shades are black and dark brown, but lesions can also include patches of tan, red, blue, or white within the same spot. This uneven mix of colors within a single lesion is one of the hallmarks that separates melanoma from a normal mole or freckle.
In terms of shape, these lesions are usually asymmetrical, meaning one half doesn’t mirror the other. The edges tend to be ragged or notched rather than smooth. Most vulvar melanomas measure over 7 millimeters across (roughly a third of an inch), and they most often appear flat against the skin. Some present as raised bumps or nodules instead. Over time, a lesion may change in size, shape, or color, which is a key warning sign.
The ABCDE Rule Still Applies
The same screening framework used for skin melanoma elsewhere on the body works here too:
- Asymmetry: the two halves of the spot don’t match
- Border irregularity: edges are uneven, jagged, or blurred
- Color variation: multiple shades of brown, black, or other colors in one lesion
- Diameter: larger than 6 millimeters (about the size of a pencil eraser)
- Evolution: any change in size, shape, or color over weeks or months
Any pigmented spot on the vulva that meets one or more of these criteria warrants a closer look. The challenge is that vulvar skin is mucosal, so normal pigmentation in this area can already look uneven, making self-assessment harder than it is on, say, an arm or leg.
When There’s No Dark Color at All
Roughly 2% to 10% of vulvar melanomas are amelanotic, meaning they produce little or no melanin pigment. Instead of appearing dark, these lesions look pink, reddish, or grayish-white. They can resemble a small polyp or fleshy bump, which makes them easy to mistake for other conditions like a cyst, wart, or even squamous cell carcinoma. Amelanotic vulvar melanoma is more common in postmenopausal women. Because it lacks the classic dark coloring people associate with melanoma, it’s frequently diagnosed later than pigmented forms.
Where It Usually Appears
Vulvar melanoma can develop anywhere on the vulva, but the most common locations are the inner lips (labia minora) and the clitoral area. These are mucosal or semi-mucosal surfaces that don’t get sun exposure, which is one reason vulvar melanoma behaves differently from sun-related skin melanomas on other parts of the body. Its causes aren’t fully understood, and the usual risk factor of UV exposure doesn’t apply here the way it does for melanoma on the arms, legs, or face.
How It Differs From Harmless Dark Spots
Vulvar melanosis, a benign condition, causes dark patches on the vulva that can look strikingly similar to melanoma. These harmless spots range from light tan to deep black and can be asymmetrical with poorly defined borders. In some cases, vulvar melanosis is so dark it’s nearly indistinguishable from melanoma to the naked eye.
There are subtle differences, though. Benign melanosis typically shows only shades of brown and black. When a pigmented vulvar lesion also contains gray, blue, or white coloring, that combination points more strongly toward melanoma. Under dermoscopy (a magnified skin exam), melanomas frequently show a blue-white veil and abnormal blood vessel patterns that benign spots lack. This is why a biopsy is the only way to confirm or rule out melanoma for any suspicious vulvar spot. Visual inspection alone, even by experienced clinicians, isn’t reliable enough.
Symptoms Beyond Appearance
Vulvar melanoma isn’t always painless. Common accompanying symptoms include persistent itching, burning, or bleeding on the vulva that doesn’t resolve on its own. Some people experience pelvic pain, particularly during urination or sex. Others notice no symptoms at all and only discover the lesion during routine self-examination or a gynecological visit. A spot that bleeds when touched or rubbed, or one that develops a sore or ulcer on its surface, is particularly concerning.
Why Thickness Matters
Once a vulvar melanoma is biopsied, the single most important measurement is how deep it has grown into the skin, reported in millimeters. Lesions 1 millimeter or thinner are considered early-stage and carry a significantly better outlook. Those between 1 and 4 millimeters are intermediate, while anything thicker than 4 millimeters is classified as deep and carries the highest risk of spread. Whether the surface is ulcerated (broken open) also affects staging. Unfortunately, vulvar melanomas are often diagnosed at greater depths than melanomas on sun-exposed skin, partly because the location makes them harder to spot early.
Who Is Most Affected
Vulvar cancer overall is most commonly diagnosed around age 69, and melanoma of the vulva follows a similar pattern, predominantly affecting postmenopausal women. Non-Hispanic white women have the highest rates of vulvar cancer at 3.1 per 100,000, while non-Hispanic Asian and Pacific Islander women have the lowest rates at 1.0 per 100,000. Unlike squamous cell vulvar cancer, vulvar melanoma is not strongly linked to HPV infection. Its rarity means many women and even some healthcare providers aren’t aware it exists, which contributes to diagnostic delays.
Regular self-examination of the vulva using a mirror can help you notice new or changing spots early. Any pigmented lesion that is new, growing, multicolored, or symptomatic deserves professional evaluation and likely a biopsy.