Melanoma

Melanoma is the most dangerous type of skin cancer, originating in the melanin-producing cells known as melanocytes. It primarily occurs in the skin but may also appear in the mouth, intestines, or eyes. In women, melanomas commonly occur on the legs, while in men, they are frequent on the back. The primary cause is ultraviolet (UV) light exposure, either from the sun or tanning devices.

Signs and Symptoms

Early signs of melanoma include changes in the shape or colour of existing moles or the appearance of a new lump on the skin. Later stages may show itchiness, ulceration, or bleeding. The mnemonic "ABCDEEFG" helps in identifying melanoma:

• Asymmetry
• Borders (irregular)
• Colour (variegated)
• Diameter (greater than 6mm)
• Evolving over time
• Elevated above the skin surface (for nodular melanoma)
• Firm to touch (for nodular melanoma)
• Growing (for nodular melanoma)

Causes and Risk Factors

The primary cause of melanoma is DNA damage from UV light exposure. Genetics also play a significant role, particularly in individuals with dysplastic nevus syndrome. Risk factors include having many moles, family history, and poor immune function. UV radiation from tanning beds and occupational exposure, such as working in aeroplanes, increases the risk.

Diagnosis

Diagnosis involves visual inspection, dermoscopy, and sometimes reflectance confocal microscopy for better sensitivity. Biopsies confirm the diagnosis, with methods including excisional, incisional, or punch biopsies. Histopathologic examination determines the melanoma type, such as superficial spreading, nodular, lentigo maligna, or acral lentiginous melanoma.

Prevention

Preventive measures include minimising UV exposure by using sunscreen, wearing protective clothing, and avoiding tanning beds. Sunscreens with SPF 50 or higher are recommended. Balancing sun exposure is essential to maintain adequate vitamin D levels without increasing melanoma risk.

Treatment

Surgery

Surgical excision with adequate margins is the standard treatment for melanoma. Depending on tumour size, sentinel lymph node biopsy may be performed. Mohs surgery or margin-controlled excision is used for melanomas in situ.

Immunotherapy

Immunotherapy, including checkpoint inhibitors like pembrolizumab and nivolumab, shows significant improvement in survival rates for metastatic melanoma. Cytokine therapies (e.g., IL-2) and immune checkpoint inhibitors (e.g., ipilimumab) are used, though they can have severe side effects.

Chemotherapy

Chemotherapy, such as dacarbazine, is used for metastatic melanoma. Targeted therapies, especially for BRAF mutations, involve BRAF inhibitors like vemurafenib and MEK inhibitors like trametinib. Combination therapies often yield better outcomes.

Radiotherapy

Radiation therapy is used post-surgically or for inoperable metastases. It can reduce local recurrence rates but does not improve overall survival.

Prognosis

Prognosis depends on tumour thickness, ulceration presence, lymph node involvement, and metastasis. Stage IV melanoma, with distant metastasis, has a poor prognosis with a five-year survival rate of less than 10%. Early detection and treatment significantly improve outcomes.

Epidemiology

Globally, melanoma incidence is highest in Australia and New Zealand. In the UK and the USA, melanoma rates are increasing, particularly among people of European descent. Fair-skinned individuals are at higher risk due to lower melanin levels providing less UV protection.

---

Self-assessment MCQs (single best answer)

What is the primary cause of melanoma?

Which mnemonic is used to help identify melanoma?

In women, where are melanomas most commonly located?

Which of the following is not a sign of melanoma?

What type of biopsy is commonly used to confirm a melanoma diagnosis?

Which treatment has shown significant improvement in survival rates for metastatic melanoma?

Which of the following is not a preventive measure against melanoma?

Which type of melanoma is characterised by being firm to touch and growing?

What is the prognosis for Stage IV melanoma?

Which country has the highest incidence of melanoma?