Very dark, irregular patches on the vulva characterize vulvar melanosis. Though it may look similar to cancerous lesions, it’s typically harmless and doesn’t require treatment.

Irregular lesions of the vulva can sometimes be a warning sign of skin cancer. However, this isn’t always the case. Though vulvar melanosis closely mimics the appearance of cancerous skin lesions, like vulvar melanoma, it’s benign and typically isn’t a reason for concern.

That being said, due to the similarities to cancerous lesions, it’s always a good idea to visit a medical professional for a diagnosis. Here’s what to know.

Vulvar melanosis lesions are relatively rare. The appearance may:

  • be asymmetrical or irregularly bordered
  • occur on the labia minora, followed by the labia majora, but may occur on any mucosal area in the region
  • not change in size or shape over time in about 70% of incidences
  • gradually change in size or pigmentation over the course of about 18 months in about 30% of instances

The exact cause of vulvar melanosis remains unknown, but scientists think it’s at least partly linked to the hormone estrogen. This is because estrogen may stimulate skin pigmentation by increasing melanin production in the vulva. However, further research is still needed to confirm this link.

With that in mind, experts associate this condition with:

  • people of childbearing age
  • those undergoing estrogen hormone therapy
  • those taking birth control pills

Experts also associate the condition with lichen sclerosis, a chronic inflammatory skin condition, and human papillomavirus (HPV) infections.

However, experts aren’t sure why there’s an association between those with these conditions and vulvar melanosis yet. It is important to remember that correlation doesn’t necessarily mean causation, so more research is needed before drawing conclusions about its origin.

To determine whether the vulvar lesion is vulvar melanosis or another underlying condition, a doctor will typically:

  • Conduct a visual exam: This includes assessing the lesion’s size, color, shape, distribution, etc.
  • Perform a dermoscopy: Dermoscopy involves using a strong magnifying glass to assess the lesion’s characteristics in greater detail.
  • Take a detailed medical history: This includes assessing when the lesion first appeared, its changes over time, hormonal factors, and your family’s history of skin conditions.

If any features suggest a condition requiring treatment, the doctor will consider performing a biopsy, which involves taking a small skin sample for testing.

Keep in mind the condition doesn’t just mimic melanoma — it may also be mistaken for conditions, like:

  • vitiligo, characterized by pigmentation changes
  • atypical genital nevi, which are benign, irregularly shaped moles
  • seborrheic keratosis, which is harmless skin growth
  • other types of hyperpigmentation

Since vulvar melanosis is a benign condition, it doesn’t typically require treatment. The condition may fade over time, particularly in older patients. However, doctors recommend regular checkups to monitor any changes, just in case.

In a 2020 study of 129 women with vulvar melanosis, no cancerous evolution was found in any person during an average follow-up time of 13 years.

After you have your condition assessed, you should talk with a doctor about scheduling your next follow-up appointment. If you have a concurrent skin condition or other skin cancer risk factors, such as a family history, a doctor may recommend more regular testing.

Skin cancer: Self-checks and screening

It’s also a good idea to assess the area yourself often. If you notice any changes, such as in size or color, consider speaking with a doctor about another assessment.

When assessing for potential warning signs of skin cancer, the ABCDE rule is often used. It stands for:

  • Asymmetrical: Cancerous moles may be uneven in shape and size.
  • Border: They may have an irregular border.
  • Color: They may not be the same color all over.
  • Diameter: Moles larger than 1/4 inch may be more likely to be malignant.
  • Evolving: Their appearance may change.

The Skin Cancer Foundation also recommends scheduling a professional skin cancer screening at least once a year to remain protected. The process should typically take just 10 minutes.

If insurance or finances are prohibitory factors and you’re located in the United States, consider checking if any facilities offer free skin cancer screenings near you.

Can vulvar melanosis cause bleeding?

Vulvar melanosis can not cause bleeding. If you do experience symptoms, like bleeding, a lump on the vulva, or an open sore, you should speak with a doctor immediately. These symptoms can often be a sign of vulvar melanoma, which is a type of vaginal cancer.

Is vulvar melanosis serious?

Vulvar melanosis is a benign condition and isn’t life threatening. However, if you notice changes in the appearance of your vulva, such as dark spots, it is important to speak with a doctor to rule out any underlying conditions, like vaginal cancer.

Though vulvar melanosis may look very similar to melanoma, it’s harmless and doesn’t require treatment. That being said, it can be beneficial to have any questionable lesions evaluated by a healthcare professional.

Medical professionals recommend regular self-checks for skin changes on your entire body. Consider scheduling a professional skin cancer screening at least once a year to remain protected.