Subungual (Nail) Melanoma: Causes, Diagnosis, Treatment

Subungual (Nail) Melanoma: Causes, Diagnosis, Treatment


Melanoma is a type of skin cancer that starts in the epidermis, the top layer of skin. Specifically, this type of cancer affects the melanocytes, the cells that give your skin its pigmentation or color. When melanoma begins in or around the fingernail or toenail, it’s called subungual melanoma, or nail melanoma for short.

Nail melanoma is uncommon. As part of a broader category of cancers called acral-lentiginous melanoma, it’s only responsible for about 2-3% of skin melanomas. However, nail melanoma is often found in its later stages, which affects treatment success.

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Many people know to check their skin for warning signs of cancer, like new or changing moles, but forget to examine their nails for any changes. These are the most common signs and symptoms of nail melanoma: 

  • Dark streak: Also called longitudinal melanonychia, this is the most common symptom of nail melanoma and often the first to appear. It looks like a dark brown or black streak running vertically along the entire length of the nail plate.
  • Inflammation: You may notice red or pink bumps on or under your nail or experience swelling or infection of the nail.
  • Skin discoloration: The skin around the edges of your nail may become discolored. It may look brown or black, also called Hutchinson’s sign. It could lack normal pigmentation (amelanotic), appearing pinker or redder than your normal skin tone.  
  • Nail splitting: The nail may split or crack vertically down the middle.
  • Onycholysis (nail bed separation): Nail melanoma can cause the nail to lift away from the nail bed or even fall off completely.
  • Bleeding: The areas around or underneath your nail plate may bleed, causing thin red streaks.

Subungual melanoma is usually caused by a type of cancer called acral-lentiginous melanoma. When an excess amount of melanocyte cells is produced, some may grow abnormally, causing tumors or destroying surrounding tissue. Nail melanoma usually starts in the nail matrix, which is located at the base of the nail and is responsible for forming new nail growth.

Unlike many other melanomas, nail melanoma is usually not caused by ultraviolet (UV) light exposure. The most common causes are your overall melanin production, physical trauma or damage to the nail, or certain medical conditions (like nail psoriasis).

Risk Factors

Nail melanoma is rare compared to other types of melanomas and skin cancers, but some people are more at risk of developing it than others, primarily because of their family history, ethnicity, and age: 

  1. Family history: You are more likely to develop nail melanoma if you have a first-degree relative with any type of acral-lentiginous melanoma.
  2. Age: Nail melanoma is most commonly diagnosed in people between the ages of 50-70.
  3. Ethnicity: Although subungual melanoma affects all races fairly equally, it represents a far greater percentage of melanomas in African Americans, Asians, and Hispanics. 

To diagnose nail melanoma, your healthcare provider will take your medical history and do a physical examination. After that, some type of biopsy—a tissue sample taken to be studied under a microscope in a lab—is usually needed to confirm that you have melanoma and not another condition with similar symptoms. The biopsy is typically taken from your nail matrix but could also come from your nail bed.

Sometimes, a non-invasive nail clipping taken by your provider can give them enough information to diagnose you with melanoma or another condition. But many people need to have one of several types of biopsies performed to diagnose nail melanoma:

  • Punch biopsy: Your provider may use a sharp circular tool to extract a tissue sample from a deeper layer of the epidermis.
  • Shave biopsy: Less invasive than a punch biopsy, a shave biopsy removes skin cells from the skin’s surface with a surgical blade.
  • Excisional biopsy: This type of biopsy involves making an incision somewhere in the nail (in the nail matrix or nail bed or along one of the nail folds) to remove tissue surgically.

Depending on the part of your nail affected and the type of biopsy being done, your provider may need to remove part of the nail plate from the finger being biopsied. Nail biopsies can be painful, so you can expect to receive local anesthesia.

Bleeding and scarring are common complications of all nail biopsies, and the nail may not grow back correctly after your procedure.

Stages of Nail Melanoma

The stages of subungual melanoma follow the typical staging for all types of melanoma cancers: stage 0 through stage 4. The condition of the tumor, whether or not the cancer has reached the nearby lymph nodes, and whether or not the cancer has metastasized to other parts of the body all determine the stage of melanoma.

  • Stage 0: The tumor is small and only located in the epidermis (melanoma in situ). 
  • Stage 1: The tumor is less than two millimeters thick and has crossed into the dermis (the skin layer beneath the epidermis). The skin surrounding the tumor may or may not be ulcerated (broken down).
  • Stage 2: The tumor is at least one millimeter thick and could be more than four millimeters thick. It may or may not be ulcerated.
  • Stage 3: The tumor is any size and may or may not be ulcerated. It has spread to nearby lymph nodes but not other body parts.
  • Stage 4: The tumor is any size and may or may not be ulcerated. It may or may not have spread to nearby lymph nodes but has spread to other body parts.

Most people with nail melanoma will need to undergo a surgical procedure to remove the tumor-affected tissue, stop cancerous cell growth, and prevent cancer spread. Radiation and immunotherapy are also options. 

  • Surgery: Historically, providers have always recommended amputation of the affected nail or finger. More recently, some evidence has shown that the use of more conservative surgeries that only remove the cancerous areas and preserve more of the nail and finger are effective in some early-stage cases. Your healthcare provider can help you determine the best course of action for your diagnosis.
  • Radiation: Typically, radiation and chemotherapy aren’t used to treat subungual melanoma unless it has spread to nearby lymph nodes or other parts of the body.  
  • Immunotherapy: For people with certain stages of cancer, immunotherapy treatments may increase the success rate of the surgery and decrease the risk of melanoma returning. Immunotherapy medicines help your immune system work better, identifying and destroying cancerous cells. These treatments may be provided before or after surgery.

Unlike other skin melanomas, limiting your exposure to UV light won’t reduce your risk of nail melanoma since this type of cancer is not caused by UV light. You also can’t prevent nail melanoma’s most common risk factors—family history, ethnicity, and age.

The only preventable factor that increases your risk for nail melanoma is injury or trauma to the nail. While this isn’t always unavoidable, you can reduce your risk of nail injury by:

  • Keeping nails trimmed, clean, and dry to prevent infection
  • Wearing protective footwear and gloves during physical activity, such as sports and manual labor
  • Wearing well-fitting and supportive shoes
  • Avoiding nail biting or picking
  • Avoiding cutting your cuticles during manicures or pedicures

Treating nail melanoma as early as possible reduces the risk of complications. This type of melanoma can be difficult to detect and—since surgery is almost always required—there are potential complications even from early treatment.

  • Infection: Because surgery and cancer growth both disrupt the skin barrier, there is a risk of local infection before and after treatment for nail melanoma.
  • Scarring: The nail is a relatively small area to treat with surgery, so removing affected tissue without damaging the nail and surrounding skin is difficult. In some cases, the cancerous cells themselves can cause scarring.
  • Metastasis: If left untreated, nail melanoma can spread to other parts of the finger and hand and—in later stages—metastasize to nearby lymph nodes or even other parts of the body.

Nail melanoma, or subungual melanoma, is a type of skin cancer affecting the skin’s top layers—the epidermis and dermis. It’s caused by an overproduction of melanocytes, the cells responsible for giving your skin its pigment.

Unlike other skin melanomas, exposure to UV light doesn’t increase your risk for nail melanoma, which makes it difficult to prevent. Nail injury or trauma is the most common cause. People with dark skin and people of Asian descent are also more likely than other ethnicities to develop nail melanoma.

When found early, nail melanoma is usually treatable with surgery and has a high survival rate. However, nail melanoma is harder to detect than other skin melanomas, and the survival rate is lower in the later stages of the disease.

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