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Melanoma

One of the most dangerous tumors, malignant melanoma arises from cells of the melanocytic system. Melanoma has the ability to metastasize to any organ, including the brain and heart. The incidence of melanoma is increasing and may be reaching epidemic proportions. The lifetime risk of cutaneous melanoma for white Americans in 1987 was 1 in 123. It is projected to be 1 in 90 by the year 2000. Many deaths due to melanoma may be prevented by screening those individuals at greatest risk for melanoma, melenoma, melonoma

Prevention and sun exposure.

Increased recreational sun exposure and alterations of the upper atmosphere by pollutants resulting in increased radiation may be the two most important factors in the disproportionate rise in the incidence of

Sunscreen effectiveness.

Chemical sunscreens block UVB but are less effective at blocking UVA, which makes up 90% to 95% of ultraviolet energy in the solar spectrum. Sunscreens prevent erythema and sunburn, but inhibit accommodation of the skin to sunlight, therefore their use may permit excessive exposure of the skin to

ABCDs of malignant melanoma recognition.

The goal is to recognize melanomas at the earliest stage. Compared to common acquired melanocytic nevi, malignant melanomas tend to have Asymmetry, Border irregularity, Color variegation, and

Characteristics of benign moles.

Benign moles have a more uniform tan, brown, or black color. The border is regular and the lesion is

Clinical classification

Melanoma either begins de novo or develops from a preexisting lesion, such as a congenital or atypical mole. A classification into several different types was devised after observing that the microscopic

Superficial spreading melanoma.

SSM is most common in middle age, from the fourth to fifth decade. It develops anywhere on the body, but most frequently on the upper back of both sexes and on the legs of women

Nodular melanoma.

NM occurs most often in the fifth or sixth decade. It is more frequent in males than females, with a ratio of 2:1. It is found anywhere on the body.

NM is most commonly dark brown, red-brown, or red-black and is dome-shaped, polypoid, or

Lentigo maligna and lentigo maligna melanoma.

LMM usually presents in the sixth or seventh decade. Most are located on the face, but 10% are on other exposed sites, such as arms and legs.

The radial growth phase is called lentigo maligna (LM) or Hutchinson's freckle. The radial growth phase may last for years and never develop a vertical growth phase. The risk of progression of LM to LMM varies with age, but is lower than commonly believed. For a patient aged 45 years with LM, the estimated risk of developing LMM by age 75 is 3.3%. Estimated lifetime risk of transformation to melanoma is 4.7%. For a patient aged 65 years with LM, the risk of developing LMM is 1.2%, and the lifetime risk of transformation to melanoma is 2.2%. These risk estimates apply to patients in whom LM is discovered incidentally.

LMM may have a complex patten. Years of migration and regression can produce lesions with a shape more varied and bizarre than that of SSM. The color is more uniform than SSM, but red and white may later occur. Tumors are generally in the center of the lesion, away from the border. LMM may ulcerate or undergo changes similar to other lesions when they enter the tumor stage. Nodules are usually single and generally appear when the lesion has assumed a size of 5 to 7 cm, but may occur in much smaller lesions. LMM does not have a better prognosis than other forms of melanoma; as with other types of melanoma, the prognosis depends on tumor thickness.

Acral-lentiginous melanoma.

ALM appears on the palms, soles, terminal phalanges, and mucous membranes.Similar in clinical presentation to LM and LMM, ALM has the same colors and tendency to remain flat. Like LM, plantar melanomas may remain latent for a number of years, making patients with these lesions good candidates for therapeutic cures if detected early. ALM is most frequent in blacks and Asians. The sole of the foot is the most prevalent site of malignant melanoma in non-Caucasians. Small areas of elevation may be associated with deep invasion; the tumor is very aggressive and metastasizes early. The sudden appearance of a pigmented band originating at the proximal nail fold (Hutchinson's sign) is suggestive of acral-lentiginous melanoma. Acquired melanocytic lesions on the sole larger than 7 mm in maximum diameter should be examined histologically.

Dermoscopy

Most pigmented lesions can be diagnosed on the basis of clinical criteria. However, there are many small lesions in which the distinction between a benign and malignant process cannot be made by examination with the naked eye.

Dermoscopy (epiluminescence microscopy) is a technique used to see a variety of structures in pigmented lesions that are not discernible to the naked eye. Lotion or mineral oil is applied to the surface of the lesion to make the epidermis more transparent. Then examination with a 10 ocular scope, a microscope ocular eyepiece (held upside down), or a dermatoscope (available from surgical supply houses) reveals several features that are helpful in differentiating between benign and malignant pigmented lesions. This technique provides additional criteria for the diagnosis of melanoma.

BIOPSY

Excisonal biopsy.

The prognosis and extent of surgery are based on tumor type, thickness, and level of invasion. The pathologist is capable of reporting this information if provided with an excisional biopsy of the entire lesion that is deep enough to include subcutaneous fat. Whenever possible, a margin of 1 cm should be used, as this is an adequate and definitive treatment in melanomas up to 1 mm in Breslow thickness.

Incisional or punch biopsy.

Incisional or punch biopsies are sometimes necessary in surgically sensitive areas, such as the nose and periorbital or digital regions. If total excision is impractical, an incisional biopsy should be taken from what is considered to be the deepest part of the tumor; that is, the area with the highest surface elevation. The darkest area should be sampled in flat lesions. Punch biopsy may not be sufficient because it yields such a small piece of tissue that the problem may go undetected. Studies suggest that cutting into a melanoma by incisional or punch biopsy before definitive surgery does not dislodge malignant cells that could result in systemic metastases.

PATHOLOGY REPORT

The pathologist determines the following in the pathology report:

Tumor thickness (Breslow microstage).

The tumor is step sectioned. The section with the deepest level of penetration of tumor is used to measure thickness. An ocular micrometer is placed on the microscope. The pathologist measures the thickness of the tumor in millimeters from the granular cell layer to the deepest part of the tumor. The report is given as Breslow level, followed by the depth reported in millimeters.

Tumor thickness (Clark level).

The tumor depth is reported by anatomic site (i.e., epidermis, depth in dermis, etc.) and assigned a Clark level of invasion.

Radial growth phase vs. vertical growth phase.

The growth phase of the tumor is determined by histologic criteria (see Table 22-7) (Table Not Available) .

Mitotic rate.

The mitotic rate per mm is reported.

Tumor-infiltrating lymphocytes.

The degree to which lymphocytes infiltrate and disrupt the tumor cell is reported.

Histologic regression.

Areas of epidermis that have no recognizable tumor and are flanked by areas of melanoma indicate regression.

CLINICAL STAGING, INITIAL INVESTIGATIONS, AND FOLLOW-UP

Clinical staging.

Clinical staging refers to the extent of disease as determined by physical examination. Stage I consists of local disease. Stage II is enlarged regional lymph nodes, as determined by palpation. In stage III, there is clinical evidence of disseminated disease through, for instance, positive liver scan or chest x-ray.

SURGICAL MANAGEMENT OF CLINICAL STAGE I MELANOMA

Clinical stage I melanoma is managed surgically. The surgeon must determine the resection margins and decide whether or not to perform a