melanoma

melanoma
Name	Melanoma
Caption	A typical melanoma lesion, showing asymmetry, border irregularity, color variation, and a diameter larger than 6mm.
Field	Oncology, Dermatology
Symptoms	Changing mole, new pigmented growth
Complications	Metastasis to lymph nodes, liver, brain, lungs
Onset	Any age, most common >50
Risks	Ultraviolet light exposure, many moles, fair skin, family history
Diagnosis	Dermatoscopy, biopsy
Treatment	Surgery, immunotherapy, targeted therapy, radiation therapy, chemotherapy
Prognosis	Depends on Breslow thickness, ulceration, metastasis
Frequency	Increasing globally
Deaths	~60,000 annually worldwide

melanoma is a serious form of skin cancer that arises from pigment-producing cells known as melanocytes. It is known for its potential to spread aggressively to other parts of the body, a process called metastasis, if not detected and treated early. The global incidence has been rising for several decades, particularly in regions like Australia, New Zealand, North America, and Europe. Major advances in treatment, especially with immunotherapy and targeted therapy, have significantly improved outcomes for many patients in recent years.

Signs and symptoms

The most common sign is a change in an existing mole or the appearance of a new pigmented or unusual-looking growth on the skin. Clinicians often use the ABCDE mnemonic to describe suspicious features: Asymmetry, Border irregularity, Color variation, Diameter greater than 6mm, and Evolving size, shape, or color. Melanomas can occur anywhere on the body, including under nails, on the soles of feet, and in the eye, known as uveal melanoma. Symptoms like itching, tenderness, or bleeding from a lesion are also warning signs. The most aggressive subtype, nodular melanoma, may appear as a rapidly growing black, blue, or red bump.

Causes and risk factors

The primary environmental cause is exposure to ultraviolet radiation from the sun and artificial sources like tanning beds. This radiation damages the DNA in skin cells. Major personal risk factors include having fair skin, light hair and eye color, a history of severe sunburn, especially in childhood, and a high number of moles or atypical moles known as dysplastic nevus syndrome. Genetic predisposition plays a role, with mutations in genes like CDKN2A identified in familial cases such as familial atypical multiple mole melanoma syndrome. A weakened immune system from medications or conditions like HIV also increases risk.

Diagnosis

Diagnosis begins with a clinical examination, often aided by a dermatoscope, a handheld tool that provides magnified visualization of skin structures. Any suspicious lesion is completely removed via an excisional biopsy or an incisional biopsy for pathological analysis. The biopsy sample is examined by a pathologist to confirm the presence of malignant melanocytes and to determine key prognostic features, primarily the Breslow thickness measured in millimeters and the presence of ulceration. For confirmed cases, further staging tests like sentinel lymph node biopsy, computed tomography, positron emission tomography, and magnetic resonance imaging may be used to assess for metastasis.

Prevention

Primary prevention focuses on reducing exposure to ultraviolet radiation. This includes seeking shade, wearing protective clothing, broad-brimmed hats, and sunglasses, and regularly applying broad-spectrum sunscreen with a high sun protection factor. Public health campaigns like Slip! Slop! Slap! in Australia have been instrumental in raising awareness. Avoiding the use of tanning beds is strongly recommended by organizations like the World Health Organization. Secondary prevention involves regular skin self-examination and professional screening, particularly for high-risk individuals, to enable early detection.

Treatment

The mainstay of treatment for early-stage disease is wide local excision surgery, where the tumor and a margin of healthy skin are removed. For tumors with certain features, a sentinel lymph node biopsy may be performed during surgery. If lymph nodes are involved, a more extensive lymph node dissection may be required. For advanced or metastatic disease, treatment has been revolutionized by systemic therapies. These include immunotherapy drugs like ipilimumab, nivolumab, and pembrolizumab, which block checkpoints like CTLA-4 and PD-1. Targeted therapy agents such as vemurafenib, dabrafenib, and trametinib are used for tumors with specific mutations like BRAF V600E. Radiation therapy and traditional chemotherapy are used in specific palliative or adjuvant settings.

Prognosis

Prognosis is highly dependent on the stage at diagnosis, defined by the American Joint Committee on Cancer staging system. The most critical factor is the Breslow thickness; thin tumors have a very high cure rate with surgery alone. The presence of ulceration worsens the outlook at any thickness. Once metastasis occurs to distant organs like the lungs, liver, brain, or distant skin, the disease is considered stage IV and historically had a poor prognosis. However, with modern immunotherapy and targeted therapy, long-term survival and even durable responses are now possible for a significant subset of patients with advanced disease. Ongoing research by institutions like the National Cancer Institute continues to seek improved treatments.

Category:Types of cancer Category:Dermatology