What is a blue nevus?

Moles, also called nevi, can appear on your skin in a variety of shapes, sizes, and colors. One type of mole is the blue nevus. This mole gets its name from its blue color.

Although these moles may seem unusual, they’re generally benign and not a cause for concern. But like any mole, you’ll want to keep an eye on it for changes over time. Keep reading to learn more.

What does a blue nevus look like?

Tips for identification

Moles can actually appear in all sorts of shades, not just the typical brown- or tan-colored variety you might expect.

These moles appear blue because the patch of pigmented skin creating them is set lower in the skin than brown-colored moles and freckles. The shade of a blue nevus can range from light to dark blue.

Other common characteristics are:

  • small size
  • round shape
  • raised or flat surface
  • smooth surface
  • size between 1 and 5 millimeters

It’s possible to have another type of blue nevus beyond the common variety. One of these is the cellular blue nevus.

This type:

  • sticks out more from the skin, like a nodule
  • is firmer
  • is larger in size
  • may grow with time

In extremely rare cases, your blue nevus may be malignant. Cancerous nevi may appear as a common or cellular blue nevus but develop at a later age and may start to look like ulcers. They may also have a more nodular or plaque-like form.

Blue nevi can appear in many places on the body and are generally isolated. This means you likely won’t see more than one nevus in a given area.

Some places you may encounter a blue nevus on your body include your:

  • scalp
  • neck
  • bottom of the back or buttocks
  • hands
  • feet

What causes this and who’s at risk?

It isn’t clear what causes blue nevi. They often appear in children and young adults and more frequently in women. Malignant blue nevi are rare. Men in their 40s may have a higher risk for this type.

Blue nevi can appear at any age. You may have one at birth or it could develop later in your life.

It isn’t unusual to have other types of moles in addition to a blue nevus. Most people have between 10 and 40 moles, and those with fair skin may have more moles than others. You may even notice that moles change in color, tone, or size as you grow from childhood.

When to see your doctor

Moles that develop in adulthood may be a cause for concern. If you have a blue nevus or other mole appear after age 30, see your doctor. It may be a sign of skin cancer like melanoma.

Changes to blue nevi or other moles may also be cause for concern. Keeping an eye on any abrupt or subtle shifts on your skin and moles will ensure that you catch early signs of skin cancer.

You should flag blue nevi, along with other moles, when they:

  • look asymmetrical in shape
  • have an edge that isn’t smooth
  • change in color
  • grow in size or are larger than 6 millimeters
  • stick out on top of the skin
  • are bothersome, painful, itchy, oozing, or bleeding

If you notice any of these changes, see your doctor for an evaluation.

Although your doctor may be able to diagnose the blue nevus immediately upon looking at it, they may recommend a biopsy. This can determine whether the mole is malignant.

Is removal necessary?

A blue nevus typically isn’t problematic. You can have a benign blue nevus on your skin for your entire lifetime. The only time your doctor will recommend removal is if the mole is malignant.

You can also talk to your doctor about removal if the mole is causing you discomfort. For example, if it’s rubbing against your skin or causing other irritation.

Your doctor can remove the mole by cutting it out completely or shaving it off with a surgical knife. You will likely receive a local anesthetic and may need stitches. The skin surrounding the removed mole will heal with time.

If the blue nevus reappears after removal, contact your doctor. This could be a sign of skin cancer.

Outlook

Finding a blue mole on your skin usually isn’t cause for alarm. These moles are typically benign. But if the mole appears later in life, or if a previous mole is changing over time, you should see your doctor. They can check for malignancy and advise you on your next steps.