Any change in a mole or pigmented lesion should be assumed to be malignant melanoma until proven otherwise.

Melanoma develops from melanocytes, which are pigment-producing cells derived from the neural crest that migrate during fetal development into the skin, eye, central nervous system, and mucous membranes. The most common site of melanoma is the skin, but these tumors can develop in any tissue that contains melanocytes. This cancer comprises 3% to 4% of malignancies, with 55,000 new cases each year in the United States (4). From the 1930s to the mid-1980s, there was a rapid rise in the incidence of this disease, doubling every 10 years (5). Epidemiologic studies from 1995 suggested that the incidence was leveling off in susceptible populations. Perhaps this reflects better attention to preventive measures as the causation becomes clearer (6).

The direct cause is unknown, but there is considerable evidence to suggest that ultraviolet light is the principal carcinogen. Susceptible people are those with pale complexions and reddish hair who are most prone to skin injury upon exposure to sunlight. An inverse relationship between latitude and incidence of disease has been noted for such people both in Australia and in North America. Melanoma most commonly occurs on the skin that is left uncovered, such as the back and chest in men and the arms and legs in women.

A survey of more than 8,500 malignant melanoma patients revealed a slight predominance in men (52%) over women (48%) with regard to the total number of cases reported (7). With regard to race, 98% of this group were white. In general, women tend to have a longer survival time than men. In blacks, malignant melanoma tends to occur on the palms of the hands, the soles of the feet, or beneath the nail plate; it tends to exhibit an aggressive growth pattern and early metastasis with a poor overall prognosis. The 5-year survival in the black population has been estimated to be as low as 23% (8).

Different patterns of sun exposure lead to a significant difference between men and women with respect to body location of melanoma. Men tend to have more lesions on their trunks, whereas women have more extremity lesions, particularly on the lower limbs. Melanomas in women tend to be thinner, with less tendency to ulcerate. It is unknown whether this is an inherent feature of the location or is due to easier detectability. As a result, regional lymph node involvement and distant metastases occur less often in women than in men. Therefore, men with a predominance of trunk lesions have a relatively poor prognosis, whereas women with a predominance of extremity lesions have a relatively good prognosis (5).

Yes. The dysplastic nevus syndrome is familial and is believed to be a precursor of malignant melanoma. This syndrome follows a familial pattern and is characterized by a large number of irregularly shaped nevi on the trunk. Those with dysplastic nevus syndrome are believed to have a cumulative lifetime risk of melanoma approaching 100% (9). Giant congenital nevi in children are believed to be premalignant, with a risk of malignancy reported to be as high as 40%.

Any change in size, shape, or color of a nevus, as well as any itching, ulceration, or bleeding, suggests that biopsy should be considered. Changes in size and shape occur in approximately 70% of melanomas. The change in color is usually toward increasing pigmentation; however, amelanotic melanomas do exist. In addition, pigment may fade in some areas (regression) while deepening in others. Ulceration and bleeding are late signs that usually indicate deeply invasive disease (10).

The histologic types of melanoma and their approximate incidences are as follows: superficial spreading (70%), lentigo maligna (5%), acral lentiginous (10%), and nodular (15%). Both lentigo maligna and superficial spreading melanomas have a relatively good prognosis if they are diagnosed early. These types of melanoma have a predominant horizontal growth pattern such that the melanocytes proliferate superficially along the epidermal-dermal junction and only later become locally invasive. For patients with these types of melanoma, changes in size, shape, or color can be detected while the tumor is locally noninvasive.

Acral lentiginous tumors, which develop on the palms and soles or beneath the nails, also have a prominent horizontal growth component, but they are a bit more invasive than the superficial types. These lesions, which are more common in African Americans (70% of melanomas) and Asians, present late and carry a worse prognosis. Nodular melanoma develops early deep invasion and tends to metastasize early. This type of melanoma most often presents as a uniform pigmented nodule, but 5% will be amelanotic.

Nodular melanoma carries the worst prognosis.

An incisional biopsy entails removal of only a portion of the lesion. The size of the incision varies, but the specimen must be large enough to permit an adequate diagnosis. It is best to include the most raised area of the lesion to allow adequate microstaging. An excisional biopsy entails removal of the entire lesion, leaving only normal tissue at the excised wound edge.

An excisional biopsy is preferable because it provides the pathologist with the entire lesion. This allows the deepest extent of the tumor to be determined for microstaging purposes (discussed later). Sometimes, an incisional biopsy permits only a histologic diagnosis and not an accurate determination of the depth of invasion. In addition, excision with adequate margins may obviate further intervention when a thin melanoma or preinvasive lesion is encountered. When an incisional or punch biopsy is used, it should be obtained from the most raised portion of the lesion. This will provide the greatest chance of determining depth of invasion, which in turn determines the ideal margins for excision. When the clinical appearance leaves little doubt about the diagnosis, punch biopsy allows histologic confirmation and staging with minimal disruption of lymphatics for later nodal mapping by lymphoscintigraphy.

The remaining lesion should be excised.