Melanoma is a type of skin cancer that starts in melanocytes, which are cells found in the outermost layer of skin (the epidermis). Melanocytes make a brown pigment called melanin. Melanin protects the deeper layers of skin (the dermis and subcutis layers) from the harmful effects of the sun.
When skin cancer becomes more advanced, it generally grows through this barrier and into the deeper layers where lymph and blood vessels are present. Compared to other skin cancers, melanoma is considered much less common but far more dangerous because it is more likely to spread into the deeper skin layers and metastasize.
Because most melanomas still make melanin, melanoma tumors are usually black or brown. However some melanomas do not make melanin and can appear pink, tan, or white. Melanomas can appear anywhere on the skin but are more likely to start in certain locations like the chest and back in men, the legs in women, or on the neck and face. Melanomas can also form in other parts of the body in mucosal tissue like in the eyes, mouth, and genitals but these are much less common than cutaneous melanomas. The focus for this overview is cutaneous melanoma.
Cutaneous melanomas are categorized into 4 main types: superficial spreading melanoma (the most common), nodular, lentigo maligna, and acral lentiginous melanomas.
Moles meeting the ABCDE rule (asymmetry, irregular borders, inconsistent color, diameter larger than the size of a pencil, evolving color, shape or size); a sore that does not heal; spread of pigment from the border of a spot to surrounding skin; redness or a new swelling beyond a mole border; a change in sensation-itchiness, tenderness or pain; change in the surface of a mole-scaliness, oozing, bleeding, or appearance of a bump or nodule.
Blood tests (CBC, blood chemistry tests, liver and kidney function tests, LDH tumor marker levels) and other imaging tests (chest X-ray, CT scan, CT-guided needle biopsy, MRI, PET scan) may also be ordered as part of the staging process and to plan treatment.
For patients who present with one or more signs or symptoms, a clinical exam is typically performed and may include the use of dermoscopy and digital images or photographs to better examine the suspected spot.
The primary treatment for early stage melanoma is wide surgical excision. Adjuvant therapy in the form of immunotherapy injections, radiation therapy, and/or chemotherapy may be given after surgery if there is thought to be a high risk of recurrence.
For regional melanomas, wide excision and a lymph node dissection is often performed plus possible adjuvant therapy.
If surgery cannot remove the entire tumor, other local treatments like immunotherapy injections or creams, ablation therapy, chemotherapy (local or systemic), or radiation therapy may be used instead for primary treatment.
Surgery is often possible and may be followed with entry into a clinical trial. Disseminated metastatic melanoma is typically treated with systemic therapy and may include chemotherapy, immunotherapy, and/or targeted therapy; if brain metastases are present, palliative surgery and/or radiation therapy is usually done first to prevent or ease CNS symptoms.
Demographics: Older age; male gender; ethnicity-Caucasian
Lifestyle: UV light exposure
Medical History: Dysplastic nevi; previous melanoma history; immune suppression; moles, congenital melanocytic nevi; fair complexion
Risk reduction options: Limit UV exposure; self-skin awareness; removal of abnormal moles
Inherited: Moles; congenital melanocytic nevi; fair complexion; family history of disease; inherited genetic syndromes
Associated Myriad MyRisk™ Genes: BRCA2, CDKN2A (p16INK4a), CDKN2A (p14ARF), CDK4, TP53