Malignant melanoma is a type of skin cancer that arises from pigment-producing cells known as melanocytes. Most melanocytes are found in the skin, although some also occur in the eye, brain, gut, and other organs.
Although melanoma accounts for a small percentage of all skin cancers, it is one of the most dangerous because of its ability to spread (metastasize) if not diagnosed early. Melanoma may occur on sun-exposed or, occasionally, sun-protected areas and may arise within existing moles or as a new lesion.
Over the years, a set of criteria known as the ABCDE’s of melanoma has been developed to help distinguish between benign moles and malignant melanoma.
How Is Malignant Melanoma Diagnosed?
Lesions suspicious for skin cancer are sampled, or biopsied, for microscopic examination. In the case of malignant melanoma, suspicious lesions are often removed with a thin margin of normal skin during the initial biopsy to provide the pathologist with the most complete specimen for diagnosis.
Melanoma Progression and Prognostic Factors
Melanomas begin in the epidermis, the outer layer of the skin. The earliest stage is known as melanoma in situ, meaning the cancer is confined to its site of origin. At this stage, cure rates are nearly 100%.
As melanoma progresses into the deeper layers of the skin, it becomes invasive. The most important prognostic factor for invasive melanoma is the depth of invasion into the dermis, known as Breslow’s depth. This is measured in millimeters during microscopic examination.
Superficial melanomas, with a depth under 1 mm, are typically associated with excellent cure rates, often over 95%. Deeper melanomas, especially those greater than 4 mm, carry a significantly higher risk of metastasis and lower cure rates.
Additional prognostic factors include the rate of cell division (mitotic rate) and the presence or absence of ulceration within the lesion.
Subtypes of Malignant Melanoma
The most common subtypes of melanoma include:
- Superficial spreading melanoma – tends to spread laterally within the epidermis before invading deeper layers
- Nodular melanoma – tends to grow more rapidly and invade the dermis earlier
- Acral lentiginous melanoma – occurs on distal extremities such as the feet and toes and may be diagnosed later in its course
- Lentigo maligna melanoma – occurs on chronically sun-damaged skin, such as the face or scalp, and often arises from lentigo maligna (a form of melanoma in situ)
Additional subtypes with important clinical implications include desmoplastic melanoma, which produces a scar-like reaction, and amelanotic melanoma, which lacks pigment and may appear flesh-colored.
Treatment Options for Malignant Melanoma
Early melanomas, including melanoma in situ and those less than 1 mm in depth, are typically treated with surgical excision alone. Wide local excision with appropriate margins is the most commonly used treatment. Margin width depends on the depth of invasion and may range from 0.5 cm for melanoma in situ to over 1 cm for deeper melanomas.
Although Mohs surgery is commonly used for other skin cancers, its role in melanoma treatment is still being evaluated and is not universally accepted.
Deeper melanomas may require additional staging procedures, such as sentinel lymph node biopsy, and referral to oncology specialists. In cases where melanoma has spread, newer treatments such as immunotherapy may be recommended and are typically managed by oncologists.
Follow-Up and Long-Term Monitoring
Patients with a history of melanoma or melanoma in situ require regular follow-up examinations, preferably by a dermatologist. Follow-up visits may initially occur every 3 to 6 months and can later be spaced out to annual visits.
Sun protection and regular self-examinations are essential. Due to a potential genetic component, first-degree relatives, including siblings and children, may also benefit from periodic skin cancer screening.
Frequently Asked Questions
Is melanoma a common skin cancer?
Melanoma accounts for a smaller percentage of skin cancers but is considered one of the most serious due to its potential to spread.
What is Breslow’s depth?
Breslow’s depth measures how deeply a melanoma has penetrated into the skin. It is one of the most important factors in determining prognosis.
Can melanoma be cured?
Yes. When detected early, especially at the melanoma in situ stage, cure rates are very high.
What treatments are used for melanoma?
Treatment typically involves surgical excision. More advanced cases may require lymph node evaluation, imaging, or systemic treatments such as immunotherapy.
How often should I be checked after melanoma?
Follow-up is usually every 3 to 6 months initially and may decrease to yearly visits over time, depending on individual risk factors.
If you have a concerning mole or have been diagnosed with melanoma, Dr. Berlin can provide evaluation, treatment planning, and coordinated care with appropriate specialists when needed.