Melanoma (Mucosal)

Melanomas are a type of cancer that develop from melanocytes, which are the cells that produce pigment, generally in the skin (cutaneous melanoma). However, they can also develop in the eye (ocular melanoma) and possibly other parts of the body. Mucosal melanoma refers to melanomas that occur in the mucosal surfaces of the body.

Mucosal membranes are protective membranes that line the internal structures of the body that are exposed to air, such as the respiratory, gastrointestinal, and genitourinary tracts. Their primary function is to produce and secrete mucous that lubricates the underlying tissues in the body, and traps foreign material such as bacteria.

Mucosal melanoma is more common in females, and is generally diagnosed in people over 70. However, anyone can develop this disease.

Types of Mucosal Melanoma

There are three types of mucosal melanoma, which are classified by the mucosal areas they develop in.

Head and Neck Mucosal Melanoma

Mucosal melanomas of the head and neck are the most common subtype of this disease. This type of mucosal melanoma generally presents in the nasal cavity, paranasal sinuses, and oral cavity; however, some cases have been reported in the pharynx, larynx and/or oesophagus. Unfortunately, the prognosis for head and neck melanomas is usually poor.

Vulvovaginal Melanoma

Melanomas of the vulva and vagina are less common than those of the head and neck. As the name suggests, this type of melanoma develops in the mucosal membranes of the vulva and/or vagina of the female reproductive tract. Unfortunately, the prognosis for vulvovaginal mucosal melanoma is usually poor.

Anorectal Melanoma

Melanomas of the anus and rectum are a less common subtype of mucosal melanomas. This type of melanoma often develops in the transitional zone of the anal canal (the point where normal skin meets the mucus membrane), however they can also develop in the skin of the anal verge (the area where the anal canal meets the outside skin), the transitional epithelium of the anal canal (an area where the cells lining the rectum become transition into the cells lining the anus), or in the rectal mucosa. Unfortunately, the prognosis for anorectal mucosal melanoma are usually poor.

Treatment

If mucosal melanoma is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.

Cancers can be staged using the TNM staging system:

T (tumour) indicates the size and depth of the tumour.
N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
M (metastasis) indicates whether the cancer has spread to other parts of the body.

This system can also be used in combination with a numerical value, from stage 0-IV:

Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.

Cancers can also be graded based on the rate of growth and how likely they are to spread:

Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.

Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.

Treatment is dependent on several factors, including location, stage of disease and overall health.

Treatment options for mucosal melanomas may include:

Surgery (usually a wide local excision).
Radiotherapy.
Immunotherapy.
Clinical trials.
Palliative care.

For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.

Risk factors

Because of how rare mucosal melanomas are, there has been limited research done into the risk factors of this disease. However, due to the locations that this disease develops in it is unlikely that exposure to ultra-violet (UV) radiation would be a risk factor.

Early symptoms

The symptoms of mucosal melanomas vary with location.

Head and Neck

Symptoms of head and neck mucosal melanomas may include:

Discolouration of the mouth.
Painless and/or bleeding lump.
Mouth ulcers.
Dentures no longer fitting.
Nasal obstructions.
Persistent nose bleeds.
Loss of smell.

Vulvovaginal

Symptoms of vulvovaginal mucosal melanomas may include:

Vulva discolouration.
Genital itching.
Unusual vulvar or vaginal bleeding and/or discharge.
Genital ulcers.
A lump or mass on the vulva or vagina.
Pain during/after intercourse.

Anorectal

Symptoms of anorectal mucosal melanomas may include:

Anal bleeding.
A mass on the anus.
Anal or rectal pain.
Changes in bowel habits, such as constipation and diarrhoea.

Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.

Diagnosis/diagnosing

If your doctor suspects you have a mucosal melanoma, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.

Physical examination

Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities. Depending on where it is suspected the cancer is, this may include an endoscopic inspection of the nasal/oral cavities, a pelvic exam and/or a rectal exam.

Imaging & blood tests

The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), positron emission tomography scan (PET scan) and/or ultrasound, depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.

Biopsy

Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells.

Prognosis (Certain factors affect the prognosis and treatment options)

While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage mucosal melanomas have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.

References

^{Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.}