Oral Melanoma

Oral cancer is a deadly condition that forms due to abnormal growth of mucosal cells in the mouth. Several cancer variants develop in the mouth; one among them is oral melanoma.

Oral melanoma is a pigmented entity that may develop in the oral tissues. Usually, the pigmentation depends on the source of initiation and ranges from light brown to blue-black, red or purple.

Some of the common sites prone to the formation of oral melanoma are a lower lip, tongue, and soft tissues of the mouth.

Although oral conditions with melanin pigmentations are quite common, oral melanoma itself is a rare condition.

Long term studies have shown that the incidence rate of oral melanoma has been stable for almost 25 years now.

The cause of oral melanoma is still unknown. However, it is believed that melanoma results as a consequence of sun exposure, irritation due to an oral appliance, poor oral hygiene, and risk factors like smoking and alcohol.

Treatment of oral melanoma usually depends on the severity of the lesion. Chemotherapy and radiation commonly suffice while treating oral melanoma.

Severe cases may require an additional surgical intervention to remove the lesion altogether.

In today’s article, we will discuss the causes of oral melanoma and its treatment.

What is oral melanoma?

Oral melanoma is an oral condition that primarily arises from pigment-producing cells called melanocytes.

Melanocytes are mostly present in the basal cell layer of mucosal tissue in the mouth. (1)

In the oral cavity, melanocytes are present in a ratio of 1:10 basal cells. Unlike any other forms of oral cancer, melanocytic hyperplasia is a rare condition.

Most commonly, males above 40 years of age are affected more by oral melanoma as compared to older females.

What causes oral melanoma?

Unlike cutaneous melanoma, which is caused by sun exposure, the exact cause of oral melanoma is still not clear.

However, some of the general factors that are included as risk factors of oral melanoma include –

  • Poor oral hygiene
  • A habit of smoking or alcohol consumption
  • Irritation of the soft tissue by teeth, dentures or any oral appliance
  • Presence of nevi (melanocytic proliferation)

The transformation of melanocytic cells in an existing nevus trigger accelerated growth and invasive potential.

On average, oral melanoma accounts for around 0.2 – 8% of all the oral cancers, and this incidence has been stable for almost 25 years. (2)

What are the signs and symptoms?

The most common sites involved in the formation of oral melanoma include the mandible, tongue, palate, and buccal mucosa. Often melanoma in the mouth is clinically silent.

Typical signs and symptoms of oral melanoma may include – (3)

  • Presence of a macular or nodular pigmented growth
  • Pigmentation may vary from light brown to blue-black
  • Pain and discomfort
  • Ulcerations and bleeding may be seen in advanced stages
  • Malignant lesions may include elevation and color variation
  • Swelling of the lymph nodes in the neck

How is oral melanoma diagnosed?

Diagnosis of oral melanoma is confirmed by a combination of an oral examination, pathological, and imaging studies.

Usually, oral signs and symptoms, as mentioned above, provide a tentative diagnosis of oral melanoma.

Following studies are then carried out to conclude a definitive diagnosis –

Imaging studies

CT scan is often advised to observe the extent of the tumor. Contrast enhancement can determine the exact borders of the lesion.

Additionally, contrast-enhanced CT scans can determine whether the melanoma is localized, regional, or metastatic.

Bone scan and chest x-rays are beneficial to rule out metastasis of malignant melanoma. MRI scans are used for soft tissue diagnosis.

Positive nodes on clinical examination may require surgical lymph node harvesting to determine metastasis of oral melanoma in the neck.

Pathological reports

One of the most crucial and gold standard tests to diagnose an oral melanoma is tissue biopsy.

The biopsy usually contains a part of the abnormal growth along with intact non-affected surrounding tissue.

Based on all the reports and test results, oral melanoma can be divided into three stages –

  • Stage I – localized lesion
  • Stage II – regional lymph node metastasis
  • Stage III – Distant metastasis

What are the treatments for oral melanoma?

Treatment of oral melanoma usually includes surgical approach along with drug therapy.

Surgical treatment

Early intervention enhances the survival rate. Cryotherapy and electrodesiccation are the primary treatment modalities that are advised for superficial and early lesions.

However, the treatment of choice for most oral melanomas is ablative surgery.

Ablative surgery is performed to remove the entire lesion in the mouth, leaving the site with tumor-free margins. (4)

Relapse of oral melanoma after surgical excision is believed to be around 10-20%.

Medication

Although the choice of treatment for oral melanoma is always aggressive surgical intervention, chemotherapeutic medications can be used for palliative relief.

Interferon, dacarbazine, and BCG are some of the immunotherapies suggested for patients with oral melanoma.

Follow up is crucial to check the signs of healing and relapse if any. Periodic oral examinations and radiological assessments are helpful to evaluate the current progress.

Usually, there are no preventive measures for oral melanoma. However, educating the patient and encouraging them to examine their mouth periodically can help to detect the changes at an early stage.

Take away message

Oral cancers occur as a consequence of substantial abnormal growth of the mucosal cells in the mouth.

These lesions can be benign or malignant depending on the extent and severity of the condition.

Oral melanoma is one among them and is considered as one of the most unique and rare occurrences in the mouth.

Oral melanoma is formed by increased growth of pigment-producing cells called melanocytes. This is the reason why melanotic tumors are often seen as light brown or bluish black.

The cause of this oral condition is unknown. However, some of the risk factors may include, male above 40 years of age, the habit of smoking, poor oral hygiene, and mucosal irritation due to teeth, denture, or other oral appliances.

The standard gold test to diagnose oral melanoma is tissue biopsy. Once the condition is diagnosed, the main course of treatment includes surgical excision followed by medication therapy.

Prognosis of oral melanoma is good with a five-year survival rate. Chances of relapse may be around 10-20% in aggressive and advanced cases.

Usually, no precautionary measures are followed for oral melanoma. However, the patients should be educated and encouraged to examine their mouth or visit a dentist for routine checkups.