Cancerous Toenail
Patients with toenail melanoma usually have worse outcomes than those with other types of melanomas.

A cancerous toenail, also known as a toenail melanoma or subungual melanoma, is a form of malignant melanoma of the skin that develops in the nail's internal tissues.

Subungual melanomas are incredibly uncommon, accounting for about 0.7 to 3.5 percent of all malignant melanomas globally. The big toe and thumb are the sites where 75 to 90 percent of subungual melanoma cases have been reported.

What are the symptoms of a cancerous toenail?

A cancerous toenail may have the following symptoms:

  • Brown-black discolorations of the nail bed (may look like a dark, narrow band in the nail or a wide and irregular area of pigmentation)
  • Nail thickening
  • Nail splitting
  • Nail separating from the nail bed (the white top edge of the nail may look longer as the nail lifts)
  • Bump or nodule under the nail 
  • Destruction or cracking of the nail

What are the causes of a cancerous toenail?

The exact cause of subungual melanomas is not known; however, certain factors may increase the risk of this condition. These consist of the following:

  • Multiple moles or freckles
  • A personal or family history of melanoma
  • Old age
  • Male gender
  • Immunosuppression in individuals, such as people with advanced HIV infection or organ transplant recipients

Sun exposure is one factor that doesn’t seem to have a role in subungual melanoma.

How is a cancerous toenail diagnosed?

Patient history, a physical examination, and certain other investigations are used to determine whether a toenail is cancerous (subungual melanoma).

To determine whether a pigmented nail lesion is likely to be a melanoma, doctors frequently use the "ABCDEF guidelines," which consist of the following:

  • Age between 50 and 70 years; African, Japanese, Chinese, and Native American ethnicities
  • Brown-black band more significant than 3 mm with an irregular border
  • Change in size and growth rate of the lesion
  • Digits, such as the big toe, thumb, or index finger
  • Extension of discoloration into the skin surrounding the nail (Hutchinson’s sign)
  • Family history of melanoma

A full-thickness biopsy of the nail bed is performed to confirm the diagnosis of melanoma if it is suspected.

A lymph node biopsy may be performed to evaluate whether the malignancy has progressed to lymph nodes.

Self-examination for subungual melanoma 

The American Academy of Dermatology advises examining both the skin and nails for malignancy. This may lead to early diagnosis and treatment may. Look out for the following:

  • Brown or black bands or streaks on the nails that typically appear on the thumb or big toe
  • Darker skin near the nail
  • A nail that lifts away from the finger or toe
  • Nails that are split down the middle
  • Nodules or bumps under the nail

SLIDESHOW

Skin Cancer Symptoms, Types, Images See Slideshow

What are the treatments of a cancerous toenail?

Treatment largely depends on the stage of cancer. The lesion is typically removed as part of treatment for a cancerous toenail (subungual melanoma; excision). Wide margins of healthy surrounding tissue must be removed in addition to the tumor to reduce the risk of recurrence. 

Lymph nodes must be removed if the malignancy has reached them.

Other cancerous toenail treatments include:

  • Chemotherapy used alone or with surgery
  • Radiation therapy used alone or with surgery
  • Immunotherapy, a more recent type of cancer treatment, works by triggering the immune system to fight cancerous cells
  • Targeted therapy, such as medications that specifically target the genetic KRAS and BRAF mutations that are frequently identified in subungual melanoma

What is the survival rate of a cancerous toenail?

The stage of cancer can have a significant effect on the response to treatment. Patients with subungual melanoma typically have worse outcomes than those with other types of melanomas; this is frequently the result of a delay in seeking diagnosis and treatment.

In a study that included 118 patients with subungual melanoma who underwent sentinel lymph node biopsies:

  • Stage I subungual melanoma was detected in 33 people.
  • Stage II subungual melanoma was detected in 56 people.
  • Stage IV subungual melanoma was detected in 29 people.

In this group, the overall five-year survival rate was 69.5 percent, whereas the prognosis for people with stage IV subungual melanoma was only 15 to 20 percent.

If a person sees any changes in their nail or skin that seem abnormal or don't improve, they should take immediate action, considering the subungual melanoma survival rates. The best approach to ensure treatment effectiveness is through early intervention.

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Medically Reviewed on 10/27/2022
References
Image Source: iStock image

What Is a Subungual Melanoma? https://www.webmd.com/melanoma-skin-cancer/what-is-subungual-melanomas#091e9c5e821d56bf-1-2

Melanoma: https://www.mayoclinic.org/diseases-conditions/melanoma/symptoms-causes/syc-20374884

Subungual Melanoma https://www.ncbi.nlm.nih.gov/books/NBK482480/