Melanoma

Melanoma

Melanoma is a malignant form of skin cancer originating from melanocytes, the cells that produce melanin, which gives skin its color. It is known for its potential to spread (metastasis) to other organs, including the lung, liver, bone, or brain, making it one of the most dangerous types of skin cancer. Early detection and treatment significantly improve prognosis.

Photography of a large acral lentiginous melanoma

Etiology and Risk Factors

Factors that increase the risk of melanoma include excessive exposure to ultraviolet (UV) radiation from sunlight or tanning beds, a history of sunburn, having many moles or unusual moles called dysplastic nevi, a family history of melanoma, fair skin, light hair and eye color, and weakened immunity.

Melanoma with diameter change

Pathophysiology

Melanoma begins in melanocytes in the basal epidermal skin layer. It can arise from pre-existing moles or appear on normal skin. Genetic mutations caused by UV radiation exposure can lead to uncontrolled cell growth and tumor formation.

Melanoma

Types of Melanoma

Melanoma is categorized into several types, including:

• Superficial spreading melanoma: The most common type, which grows outward before penetrating deeper into the skin.
• Nodular melanoma: Grows downward into the skin quickly and is more aggressive.
• Lentigo maligna melanoma: Occurs in older adults, mainly in sun-damaged skin.
• Acral lentiginous melanoma: Appears on the palms, soles, or under the nails and is more common in individuals with darker skin.

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Melanoma, brown lesion

Signs and Symptoms

The first signs of melanoma often involve changes in an existing mole or the development of a new pigmented or unusual-looking growth on the skin. The ABCDE rule outlines the features of early melanoma:

• Asymmetry: One half of the mole does not match the other.
• Border: Irregular, ragged, notched, or blurred edges.
• Color: Varied shades within the mole.
• Diameter: Larger than 6 millimeters, though melanomas can be smaller.
• Evolving: Changes in size, shape, color, or symptom (itching, tenderness).

Advanced melanomas might present with hardness, lumpiness, oozing, bleeding, or ulceration.

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3D melanoma cell

Diagnosis

Diagnosis involves a skin examination followed by a biopsy if melanoma is suspected. The biopsy, including excisional, incisional, or punch biopsy, is the only definitive way to diagnose melanoma. Pathological examination under a microscope confirms the presence of melanoma cells.

Differences Between a Common Mole, a Dysplastic Nevus, and Melanoma

Common Mole (Nevus):

• Not cancerous.
• Found in the majority of the population.
• Small, evenly colored, round or oval, with a sharp border.
• Does not change over time.

Dysplastic Nevus:

• Not cancerous but may have a higher likelihood of becoming melanoma.
• Larger than common moles, with mixed coloration and irregular borders.
• May change over time but does not necessarily turn into melanoma.

Melanoma:

• Cancerous.
• Can vary greatly in appearance; often presents with ABCDE characteristics.
• May develop from an existing mole or on previously normal skin.
• Capable of growing back after removal and can spread to other parts of the body.

Treatment

Treatment depends on the stage of melanoma and may include surgical removal, immunotherapy, targeted therapy, chemotherapy, and radiation therapy. Early-stage melanomas can often be cured with surgery alone, while advanced melanomas may require a combination of treatments.

Prevention

Preventative measures include avoiding excessive sun exposure, using sunscreen, wearing protective clothing, and avoiding tanning beds. Regular skin examinations for new or changing moles are crucial for early detection.

FAQs

Q: Can melanoma be completely cured? A: Yes, especially if caught early. The survival rate decreases as the cancer advances but can be managed with treatment.

Q: How often should I check my skin for melanoma signs? A: Monthly self-examinations are recommended. Additionally, regular skin exams by a healthcare professional, typically once a year, are advisable for individuals at higher risk.

Q: Can melanoma appear on parts of the body not exposed to the sun? A: Yes.

Q: How many people have melanoma? A: Melanoma is much less common than other kinds of skin cancer. But every year, about 2 in 10,000 Americans develop melanoma.

Glossary

• Acral lentiginous melanoma - A type of melanoma that occurs on the palms of the hands, soles of the feet, or under the nails, often appearing as a black or brown discoloration.

• Amelanotic melanoma - A form of melanoma that lacks the dark pigment melanin, making it harder to recognize. It can appear pink, red, or have a normal skin tone, which can delay diagnosis.

• Animal-type melanoma - A term used to describe melanomas that resemble those found in animals, particularly in their histopathological features, though its usage can vary.

• Clear cell sarcoma - A rare cancer that often resembles melanoma under the microscope, also known as melanoma of the soft parts, typically affecting tendons and aponeuroses.

• Desmoplastic melanoma - A rare form of melanoma characterized by fibrous tissue, presenting as a firm, skin-colored or slightly pigmented lump, often on sun-exposed skin.

• Epigenetics and melanoma - The study of changes in gene expression in melanoma cells that do not involve alterations to the underlying DNA sequence, affecting how genes are turned on or off in cancer development.

• Equine melanoma - Melanomas that occur in horses, often developing as benign tumors but can become malignant. They are particularly common in grey horses.

• Lentiginous melanoma on sun-damaged skin - A subtype of melanoma that develops on skin with significant sun damage, characterized by the presence of lentiginous (linear) melanocytic proliferation.

• Lentigo maligna - A precancerous condition caused by sun damage, particularly in the elderly, which can evolve into lentigo maligna melanoma if not treated.

• Lentigo maligna melanoma - A type of melanoma that begins as lentigo maligna. It is often found in areas of chronic sun exposure and can spread across the surface of the skin before penetrating more deeply.

• Melafind - A diagnostic tool that uses multispectral analysis to evaluate pigmented lesions for potential melanoma, helping clinicians decide on the need for a biopsy.

• Melanoma of the soft parts - Another term for clear cell sarcoma, which highlights the melanoma-like aspects of this rare cancer that typically affects the limbs.

• Melanoma with features of a Spitz nevus - A melanoma that histologically shares characteristics with a Spitz nevus, a type of benign mole, making diagnosis and treatment planning challenging.

• Mensacarcin - A compound with potential anticancer properties, including activity against melanoma cells, derived from natural sources or synthesized.

• Mucosal melanoma - A rare form of melanoma occurring on mucous membranes of the body, such as the nasal passages, mouth, esophagus, anus, and vaginal or urethral areas.

• Nevoid melanoma - A variant of melanoma that resembles a benign mole (nevus), making it difficult to diagnose based on appearance alone.

• Nodular melanoma - A type of melanoma that appears as a new growth or changes in an existing mole, typically presenting as a raised, firm, and darkly pigmented lesion.

• Polypoid melanoma - A subtype of melanoma characterized by a polyp-like growth, projecting above the surface of the skin, often with a fast growth rate and significant pigmentation.

• Seborrheic keratosis-like melanoma - A melanoma that mimics the appearance of seborrheic keratosis, a common benign skin growth, making clinical diagnosis challenging without biopsy.

• Small-cell melanoma - A rare subtype of melanoma characterized by the presence of small, round, and highly malignant cells, requiring careful histological examination for accurate diagnosis.

• Soft-tissue melanoma - Refers to melanomas arising in soft tissues, similar to clear cell sarcoma, emphasizing the importance of distinguishing these malignancies from more common forms of melanoma.

• Spitzoid melanoma - A type of melanoma that histologically resembles a Spitz nevus, often seen in younger patients, and requires careful evaluation to differentiate from benign lesions.

• Superficial spreading melanoma - The most common type of melanoma, which tends to grow horizontally across the top layer of the skin before penetrating deeper into the skin layers, often presenting as a flat or slightly raised lesion with varying colors.

• Uveal melanoma - A rare form of melanoma that occurs in the eye, specifically in the iris, ciliary body, or choroid, which are parts of the uvea. It is the most common primary intraocular malignancy in adults.

• Vaginal melanoma - A rare and aggressive form of melanoma that develops in the vaginal mucosa, often diagnosed at an advanced stage due to its hidden location and nonspecific initial symptoms.

Melanoma Resources
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