Oral Melanoma: Causes, Symptoms, Diagnosis, Treatment

Oral melanoma is a term used for cancer of the mucosa of the mouth. The condition gets known only when the symptoms advance and not in the initial stages. Oral melanoma is rare cancer and has a poor outlook. Mucosal melanoma account for 1% of all melanomas. ⁽¹⁾ About 80% of oral melanomas are known to occur in the mucosa of the upper jaw and mostly on the roof of the mouth. It can also occur on lips, tongue, and gum.

The causes of oral melanoma are not clear, neither it is related to the exposure to the sun.⁽¹⁾ The potential cause of this condition may include:

• Irritation due to denture
• Smoking and other tobacco use
• Alcohol
• Genetic mutations.⁽²⁾

However, no exact relationship is found between the above factors and oral melanoma.

Possible risk factors of oral melanoma include:

• Age: The mucosal melanoma diagnosis is seen mostly at the age of 65-79 years.
• Sex: Mucosal melanoma is more commonly seen occurring in females than males. Oral melanoma occurs equally in both men and women. Melanoma of the lip occurs more in males.
• Race: Oral melanoma occurs more commonly in black people and those from Japan and South Asia.

Initially, there are not many symptoms but swelling is visible alongside a brown, dark blue, or black macule.⁽¹⁾ Macule is a flat, discolored area of skin that has a normal texture and thickness.

The primary tumor has numerous groups of tumor cells surrounding it. These are known as satellite tumors.⁽³⁾

Oral melanomas have irregular borders. They show minimal symptoms until the tumor reaches the advanced stages, around 33% of people remain asymptomatic at the time they are diagnosed.⁽⁴⁾ In a later stage, symptoms such as erythema, redness of mucosa, and ulceration are seen.

Oral melanoma has a diverse range of characteristics. This makes them similar to various conditions and in turn difficult to diagnose.

These conditions include:

• Addison disease
• Kaposi sarcoma
• Drug-induced melanosis
• Melanoma macule
• Post-inflammatory pigmentation
• Peutz-Jeghers syndrome
• Moles

An ABCD scoring system is used to differentiate malignant oral melanoma from other benign lesions. This scoring system looks at:

• A- The asymmetry
• B- Border irregularity that often includes irregular notch or indentation
• C- Variation in the color that includes red, white, and blue
• D-Diameter of the lesion if its greater than 0.6 mm

The tissue is taken for biopsy in the laboratory. This is needed for a definitive diagnosis of cancer. The spread of the tumor is checked with the help of computed tomography and magnetic resonance imaging.

The primary treatment of melanoma is surgery and it aims to remove the tumor and a margin of healthy tissue that is disease-free.

Radiotherapy is recommended and it involves using high-energy x-rays to destroy the cancer cells that are left behind after surgery. This helps in achieving relapse-free survival as it controls the spread of local disease. Similarly, chemotherapy and immunotherapy are also suggested to prevent cancer from spreading.

Oral melanoma is a rare cancer of the mucosa of the mouth. The outlook is poor. The tumor is often overlooked as the symptoms go unnoticed and are diagnosed mostly in the later stages. It is best to avoid the causative factor for those who fall in the risk factor group.