Introduction:
Sinonasal melanoma is an uncommon condition involving the nasal cavities and paranasal sinuses (empty cavities within the bone connecting the nasal cavity). Sinonasal melanoma is derived from neural crest cells of the nasal mucosa. It is an aggressive tumor involving nasal cavity cells and ethmoidal cells and causes destruction of the cribriform plate of ethmoids in advanced cases. Sinonasal mucosal melanomas appear as solid, exophytic growth (an abnormal growth that sticks out from the outer surface of tissue), bulky, and with lightly pigmented areas.
What Is the Prevalence of Sinonasal Melanoma?
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Sinonasal mucosal melanomas account for 0.1 to 2 % of all melanomas and less than four percent of all head and neck cancers.
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Sinonasal melanoma involves the maxillary sinus in 16 % of cases and the nasal cavity in 60 to 70 % of cases.
What Is the Incidence?
Sinonasal mucosal melanomas mainly affect people in the age group of 60 to 90 years of age. It is more common in males than females.
What Are the Causes?
The exact cause of sinonasal melanoma is unknown, but the risk factors include:
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Genetics: Genetic alterations in the DNA (deoxyribonucleic acid) of the cells lining the nasal mucosa and sinuses.
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Exposure to Ultraviolet (UV) Light: Long-term exposure to UV (ultraviolet) rays causes alteration in the cells of the nasal mucosa.
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Workplace Exposure: Exposure to industrial chemicals like mustard gas, radium, nickel, and chromium dust by inhalation for long periods.
What Are the Signs and Symptoms?
Different signs and symptoms of sinonasal melanoma are:
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Nasal obstruction.
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Difficulty in breathing.
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Epistaxis (bleeding from the nose).
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Headaches.
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Facial pressure and tenderness (pain).
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The swelling was observed within the oral cavity (if the maxillary sinus is involved) or face.
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Fever.
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Vision disturbance.
What Are the Diagnostic Criteria?
Sinonasal melanoma is a slowly progressing tumor and shows the symptoms very late, so the diagnosis is usually delayed leading to a poorer prognosis (difficult to predict the outcome of the treatment and recovery from the condition). Various diagnostic techniques for sinonasal melanomas are :
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Computed Tomography (CT) Scans: These scans help to determine the size of the tumor mass and the extent of the spread. It also shows areas of cribriform plate destroyed by the tumor.
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Magnetic Resonance Imaging (MRI) Scans: A contrast scan is done by injecting a contrast material like gadolinium through the vein before taking scans. These scans help to diagnose the areas of the spread of cancer and neck lymph nodes involvement in advanced cases.
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Biopsy: A small piece of tissue is collected from the mass of the tumor and is sent to the lab for histopathological (microscopic examination of tissue) examination to confirm the accurate diagnosis.
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Histopathological Assessment: On histopathological examination of tissue, sinonasal melanoma usually presents with spindle-shaped neoplastic cells and areas of melanin (skin pigment produced by the body) pigmentation.
What Are the Treatment Modalities?
Various treatment modalities of sinonasal melanoma are:
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Surgical Removal: If the tumor mass is small, it is removed surgically with some margins of normal tissue to prevent the recurrence of the tumor. It is done either by open surgery or an endoscopic approach.
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Neck Dissection: It is done in advanced cases when cancer involves lymph nodes of the neck. All the involved lymph nodes of the neck are removed surgically.
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Radiotherapy: Radiation therapy is given to destroy the cancer cells and prevent the recurrence of the tumor.
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Immunotherapy or Biological Therapy: It is given after the surgical procedure to boost the immune system of the body to fight against cancer cells. Immuno-modulatory drugs (monoclonal antibodies) like Nivolumab and Cetuximab are given. These monoclonal antibody drugs bind to the cancer cells and destroy them. It inhibits the multiplication of cancer cells. Immunotherapy is proven to be effective in patients with a distant spread of cancer.
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Chemotherapy: Chemotherapeutic drugs like Dacarbazine are used to kill cancer cells and reduce their growth. The role of chemotherapy has proven to be ineffective in cases of sinonasal melanoma as compared to immunotherapy.
Can Sinonasal Melanoma Recur After Treatment?
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The risk of local recurrence is around 30 to 85 percent, and distant metastasis (spread to various body parts) is around 25 to 50 percent.
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Sinonasal melanoma is most often diagnosed in the advanced stage.
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The chances of recurrence of the tumor are high in advanced cases of sinonasal melanoma because of its aggressive spread to other organs of the body.
What Is the Survival Rate?
According to the research, because of the aggressive nature of the tumor, the survival rate of sinonasal melanoma in advanced cases is approximately five years due to the poor course of the disease.
What Research Is Going On for Newer Treatment Techniques?
Various clinical trials are going on to identify the exact cause of sinonasal melanoma and the development of new immunotherapeutic drugs and targeted therapies for the complete treatment of sinonasal melanoma and reduction in recurrence in advanced cases.
Conclusion:
Sinonasal melanoma is a slowly progressing tumor that presents the symptoms very late, which results in a delay in the diagnosis of the tumor leading to poor prognosis (difficult to predict the recovery) of the condition and, in turn, delaying the treatment. Early diagnosis and management of sinonasal melanoma are very crucial to prevent the spread of the disease to other parts of the body as it makes the outcome of treatment very complex because of the aggressive nature of the tumor. Although there are various treatment modalities for sinonasal melanoma, some of the treatments, like immunotherapies or chemotherapy, are effective for the complete cure of the disease. Further research in the development of new treatment modalities is yet to be done to decrease the death rate of patients suffering from sinonasal melanoma.
