Oral melanoma is a cancer that forms in the mucosal tissues of the mouth. An individual with oral melanoma may have no initial symptoms, and the condition may only become apparent when it is advanced.

Oral melanoma is uncommon, and doctors remain unsure about its causes and risk factors. Unlike other skin melanomas, there is no relation to sun exposure. However, experts believe that alcohol and tobacco use may increase the likelihood of developing it.

This article discusses oral melanoma’s symptoms, causes, and treatment options. It also considers an individual’s outlook following an oral melanoma diagnosis.

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Oral melanoma is a rare cancer with a poor outlook.

Oral melanoma occurs due to malignant changes in a person’s melanocytes. These cells produce the pigment melanin that gives skin its color. However, melanocytes also exist in the mucosal membranes of the mouth and other areas of the body.

According to a 2021 paper, melanoma of the head and neck account for around 25% of all melanomas, but mucosal melanomas are rare, accounting for less than 1% of all melanomas.

Around 80% of oral malignant melanomas develop in the mucosa of the upper jaw and most often in the roof of the mouth. However, it can occur on the lips, gums, or tongue.

The causes of oral melanoma remain unclear and are not related to sun exposure. However, potential causes may include:

That said, experts have not determined a direct relationship between any of these factors and the development of oral melanoma.

The initial symptoms of oral melanoma often include swelling alongside a brown, dark blue, or black macule. A macule is a flat, discolored area of skin with a normal texture and thickness.

The primary tumor may have numerous groups of tumor cells surrounding it, called satellite tumors.

As with skin melanomas, oral melanoma may have irregular borders and an asymmetrical shape.

Oral melanomas often have minimal symptoms until an advanced stage — 33% of people are asymptomatic at the time of diagnosis.

Later symptoms may also include erythema, or redness of the mucosa, and ulceration.

Oral melanomas can present with a diverse range of characteristics, making them challenging for doctors to diagnose.

Other similar conditions can include:

Doctors use the “ABCD” scoring system to help them differentiate malignant oral melanoma from benign lesions. They look for the following characteristics:

  • A: Asymmetry.
  • B: Irregularity of the border, often including an irregular notch or indentation.
  • C: Color variations such as red, white, and blue.
  • D: Diameter greater than 0.6 millimeters.

A doctor will then take a tissue biopsy for examination in the laboratory, which is required for a definitive diagnosis of any cancer.

They may also order imaging studies such as computerized tomography (CT) or magnetic resonance imaging (MRI) to check if the tumor has spread.

Surgery is the primary treatment for oral melanoma and aims to remove the tumors and a margin of disease-free healthy tissue.

Doctors may also recommend radiotherapy, which involves using high-energy X-rays to destroy any cancer cells that remain after surgery. They may use it to control local disease that has not spread as it can help improve an individual’s chances of achieving relapse-free survival.

As oral melanoma is rare, doctors are not certain about using chemotherapy and immunotherapy as part of the treatment regime. However, they may recommend these therapies to help prevent the cancer from spreading.

Generally, the outlook for oral melanoma is poor. Compared with other melanomas, oral mucosal melanomas have the lowest 5-year survival rate, at approximately 15–30%. This means that fewer than 1 in 3 individuals are alive 5 years following their diagnosis.

This is likely because oral melanoma is often overlooked, and people may not develop obvious symptoms until the disease is advanced.

As with causes, the risk factors for oral melanoma are largely unknown. Possible risk factors include:

  • Age: The peak age for diagnosis of mucosal melanoma is 65–79 years.
  • Sex: Mucosal melanomas are more common in females than males. However, with oral malignant melanoma, the distribution is equal. With melanoma of the lip, slightly more males are at risk.
  • Race: Malignant melanoma of the mouth is more common in Black people and individuals from Japan and South Asia.
  • Human Papillomavirus (HPV): Some sources suggest an association with HPV infection, but this is not well-researched.
  • Genetic mutations: Preliminary research, using a very small sample, found mutations present in several people with oral melanomas.

Oral melanoma is a rare cancer of the oral mucosa. As it is uncommon, the causes and risk factors are mainly unknown. However, it seems that alcohol and tobacco smoke play a role in developing the disease.

Surgical excision of the site is the primary treatment of oral melanoma. Doctors may also recommend radiotherapy to kill any remaining cancer cells following the surgery.

Typically, the outlook for an individual with oral melanoma is poor. Doctors may overlook these tumors, or an individual may not notice symptoms until later, meaning oral melanoma is often in its advanced stages at diagnosis.