Melanoma

1

What is melanoma?

The term melanoma implies a malignant tumor that arises from melanocytes. The most malignant of all skin cancers, melanoma usually forms from a preexisting nevus or mole but may develop de novo. It accounts for <1% of all skin cancers, but the vast majority of skin cancer deaths.

2

What is the incidence of melanoma?

It is the sixth most common cancer in the United States and currently is the cancer with the most rapid rise in incidence in the United States. The overall incidence is approximately 20/100,000 population, with a lifetime risk of approximately 1 in 75. Over 76,000 new cases of melanoma are reported each year, with more than 10,000 deaths from the disease.

3

What are the types of moles (nevi)?

• Intradermal: The most benign form

• Junctional: The junctional component may be the site of melanoma formation

• Compound: Intradermal and junctional together; intermediate activity

• Spitz: Once called juvenile melanoma, it is actually a spindle cell epithelioid nevus that is quite benign

• Dysplastic: The most likely to turn malignant (especially in dysplastic nevus syndrome)

4

What are the risk factors in melanoma formation?

• Large number of moles (>50 moles >2 mm in diameter)

• Changing nevi

• History of melanoma

• Family history of melanoma

• Light, poorly tanning skin; blonde or reddish-brown hair

• History of episodic, acute, severe sunburns

• Dysplastic nevus syndrome, or familial atypical multiple mole melanoma syndrome (FAMMM)

5

What is the familial melanoma syndrome?

The inherited FAMMM syndrome has been defined as the occurrence of melanoma in one or more first- or second-degree relatives and the presence of >50 moles of variable size, some of which are atypical, histologically. The risk of melanoma in this syndrome runs as high as 100% in the person’s lifetime. People with FAMMM frequently have a mutation in p16 mapped to chromosome 9.

6

What are common sites of melanoma development?

The most common sites are the posterior trunk in men and lower extremities in women. All sun-exposed areas are possible sites. Less common sites for melanoma formation are the soles of the feet, palms, and genitalia. Unusual noncutaneous sites for melanoma formation are the eye, anus, and gastrointestinal tract.

7

What are the warning signs of melanoma?

Skin lesions that display:

• A = A symmetry

• B = Irregular b order

• C = C olor: Variable, spotted, often very black with irregular tan areas, red or pink spots, ulcerated when advanced (bleeds easily)

• D = D iameter (>5–6 mm)

• E = E nlargement or E levation

8

What are the main types of melanoma and their incidence?

• Superficial spreading: 75% of all cases; most common

• Nodular: 15% of cases; most malignant, well circumscribed, deeply invasive

• Lentigo maligna melanoma: 5% of cases; relatively good prognosis.

• Acral lentiginous: 5% of cases; most common type in people of color; appears on the soles, palms, subungual sites.

• Other rare types include desmoplastic, ocular, and mucosal melanomas

9

Which moles should be considered for removal?

Growing and darkening nevi should be excised, especially in sun-sensitive patients. Itching is a sign of early malignant change. Ulceration is a late sign. Because melanoma may be familial in origin, children of patients with melanoma should be carefully screened for very dark nevi.