Mucosal melanomas

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Melanomas are malignancies that begin in the melanocytes, which are cells of the epidermis that define the colour of the skin. Much more rarely, in less than 5% of cases, melanomas can originate from melanocytes located in extracutaneous sites, such as inside the ears, in the nose, mouth and genital areas. In this case, tumours are called mucosal melanomas.

Mucosal melanomas of the aerodigestive tracts are extremely rare tumours. Their usual sites are the cervico-facial region, in most cases in the paranasal sinuses and in the oral cavity. 

Both the melanoma of the oral cavity and the mucous melanomas of the nasal cavity and paranasal sinuses are difficult to diagnose, extremely aggressive and with a tendency to metastasize. In fact, these types of tumour are difficult to control because of their multifocal nature and the anatomical limitations of the cervico-facial region.

Causes of mucosal melanomas

The causes of mucosal melanomas of the head and neck are still unknown, although according to some studies even these forms of melanoma could be affected by massive exposure to UV rays. In fact, it seems that excessive sun exposure can cause alterations of melanocytes regardless of their position in the human body. Other recent studies have shown mutations of the c-Kit receptor in some mucosal melanomas.
In any case, some risk factors that can contribute to the development of mucosal melanomas include:

• Age >50
• Smoking habit
• Unhealthy lifestyle
• Immunodeficiency disorders
• Continuous contact with potentially harmful chemical substances

These risk factors are common to all non-cutaneous melanomas.

Symptoms of mucosal melanomas

Mucosal melanomas are often asymptomatic and the first symptoms usually arise at an already advanced stage.

These symptoms also depend on the location of the tumour and can include:

• Presence of nodules/masses in the oral or nasal cavities
• Nosebleed
• Appearance of dark spots inside the mouth
• Ulcers formation

Diagnosis of Mucosal melanomas

Mucosal melanomas develop in areas that are not much exposed and are difficult to control; as a result, a delay in diagnosing the tumour when it is already at an advanced stage is not uncommon.

In case of suspected mucosal melanoma, a biopsy is required in order to define with certainty the condition of the lesion found by analysing the epithelial tissue sampled. 

If the diagnosis is confirmed, imaging techniques (such as MRI, CT scanning and X-rays) are advisable in order to evaluate the extent of tumour spread to the rest of the body, particularly in the cervico-facial area.

Treatment of mucosal melanomas

Given the extreme aggressiveness of this type of melanoma, a multidisciplinary approach is recommended in order to integrate all the available techniques and improve the patient's outcome.

Although the reference treatment is surgery followed by radiation therapy, numerous studies have confirmed the effectiveness of irradiation techniques such as hadrontherapy, especially in cases of patients not eligible for surgery. 

In addition, hadrontherapy, thanks to its dosimetric selectivity, makes it possible to treat tumours located in critical sites, such as mucosal melanomas of the head and neck.