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Epidemiology The incidence of melanoma has increased dramatically in recent times, with a 120.5% increase (6.4-14.0 cases per 100,000 white individuals) in the United States from 1973-1994. The incidence of melanoma of the head and neck has similarly increased (1.7- 4.1 cases per 100,000 white individuals). Much of this increase can be attributed to increased sun exposure in the general population, especially early in life, or to intense intermittent exposure. Most melanomas are thin, early lesions. However, the increased incidence of melanoma is observed in all thicknesses of lesion. Fortunately, the incidence of melanoma may be stabilizing, especially in females and young age groups. Risk factors Many risk factors for melanoma have been identified. The most important risk factor is exposure to sunlight, particularly UV-B radiation. Recreational or intermittent exposure is a particular risk factor because of the exposure of parts of the body that are not typically exposed to sunlight. Sunburns early in life and exposure to UV radiation from tanning beds are other factors in the development of melanoma. People with fair or red hair, blue eyes, and light-colored skin are most prone to develop melanoma, particularly if they burn easily. Freckling and benign nevi also indicate an increased risk for melanoma development. The number of nevi (especially if dysplastic) appears to be more important than the size of nevi. Having at least 1 affected first-degree relative also increases a person's risk of melanoma. For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education articles Skin Cancer and Skin Biopsy.
Great advances have been made in recent years in the treatment of melanoma. However, the best hope for the patient with melanoma remains early diagnosis. Classic warning signs and symptoms of melanoma that aid early diagnosis include any lesion that changes color; any lesions that becomes or friable; any lesion that changes size or elevation; any lesion that is tender, painful, itches, oozes, crusted, or ulcerated. Always keep in mind the ABCDEs of melanoma. Suspect melanoma in any skin lesion that is asymmetric (A), that has an irregular border (B), that is variegated or dark in color (C), that is larger than 6 mm in diameter (D), or that is elevated (E). Experienced visually inspection is often the key to distinguishing a melanoma from other common benign pigmented skin lesions (eg, lentigo simplex, junctional nevus, compound nevus, intradermal nevus, blue nevus, solar lentigo, seborrheic keratosis). A regular full-body cutaneous examination by the primary care provider is key to diagnosing melanoma in an early stage. Remember the ABCDEs when examining the entire cutaneous surface of the head and neck, and pay particular attention to sun-exposed areas. Certain areas are often overlooked: the scalp, the oral cavity, and the neck. The scalp can easily be examined by using a comb to separate the hair. The oral cavity is often forgotten in the search for melanoma; however, its importance cannot be understated. To achieve any hope of curing a mucosal melanoma, oral pigmented lesions must be found and a biopsy sample obtained early. The neck is important in the search for regional metastases. Types of cutaneous malignant melanomaThe 3 main types of cutaneous malignant melanoma on the head and neck are superficial spreading, lentigo maligna, and nodular lesions. Other types include acral lentiginous and mucosal lesions. Superficial spreading melanoma accounts for approximately 50% of all head and neck melanomas. The growth of superficial spreading melanoma is biphasic, with an initial radial growth phase, when growth is confined to the epidermis, followed by a vertical phase, when melanocytes invade deeply into the papillary and reticular dermis. Approximately 20% of head and neck melanomas are of the lentigo maligna type. These typically are flat melanomas with a long radial growth phase. Lentigo maligna are regarded as the least invasive form of melanoma. Lentigo maligna arise in sun-exposed areas, particularly the face, neck, and extremities. Nodular melanomas are aggressive lesions that have only a vertical growth phase. These lesions make up 30% of head and neck melanomas. Acral lentiginous melanoma is primary observed in dark-skinned individuals, particularly in non–sun-exposed areas, such as the palms of the hands, the soles of the feet, and the nail beds. This type of melanoma is rarely found in the head and neck. Mucosal melanoma is a rare form of melanoma that accounts for approximately 4% of cases of head and neck melanoma. These tumors are somewhat different from cutaneous melanoma in that tumoral thickness is not well correlated with the prognosis. Patients with mucosal melanoma of the head and neck have a poor prognosis regardless of the thickness of the primary lesion. StagingMany different staging systems for melanoma are available. The most common system simply classifies melanomas on the basis of their local, regional, and distant characteristics, as follows:
Clark levels Two popular microstaging systems for melanoma are the Clark levels and the Breslow thickness classifications. The Clark method is used to stage the melanoma according to its depth of penetration into the deep levels of skin, as follows:
In the Clark system, level I or II lesions are typically tumors growing in the radial phase. Level III and higher tumors have reached the vertical growth phase. Breslow thickness The Breslow thickness classification is used to stage melanoma according to the thickness of the lesion, as measured from the granular layer of the epidermis to the deepest point of tumor infiltration in the vertical dimension. The system is as follows:
The Breslow thickness classification is generally the most widely accepted method because its results are most consistently reproducible. Prognostic factorsThe 2 most important prognostic factors for cutaneous melanoma of the head and neck are the thickness of the tumor and the status of the regional lymph-node basin. Many other factors have been associated with prognosis (eg, site of lesion, presence of ulceration, histologic type of lesion, satellitosis, sex of the patient, mitotic rate). Although these other factors may be important contributors to the overall behavior of the lesion, they are relatively minor variables compared with the thickness and presence of lymphatic metastases.
Biopsy The key to biopsy of suspected melanoma lesions is to full-thickness biopsy because the prognosis and treatment of the melanoma depends on the thickness of the lesion. Excisional biopsy is the best choice for small lesions or for large lesions in cosmetically favorable locations. Excisional biopsy should extend down to the subcutaneous fat, with a small (2-3 mm) peripheral margin. Punch biopsy can be performed for large lesions or for lesions with a low suspicion of melanoma in a cosmetically unfavorable location. Perform punch biopsy at the highest or thickest point of the lesion. Incisional biopsy is not recommended. Likewise, techniques that do not permit a full-thickness sample, such as shave or curette biopsy, are not recommended. Do not definitively treat pigmented lesions with laser therapy, electrocautery, or freezing unless biopsy analysis proves them to be noncancerous. Excision Surgeons operating in the head and neck face the difficult dilemma of removing enough tissue to obtain adequate tumor-free margins yet retaining normal tissue in a cosmetically sensitive area. The desire to retain tissue may contribute to the generally increased recurrence rate of head and neck melanoma. In 2 prospective trials, Balch et al in 1993 and Veronesi et al in 1988 examined the local recurrence rate of melanoma. On the basis of the results, margins of 1 cm are proposed for lesions smaller than 1 mm, and margins of 2 cm are proposed for lesions of 1-4 mm. In general, the margin of excision should be approximately 10 times as wide as the deepest penetration of tumor; therefore, a 2-cm margin is recommended for a lesion that is 2 mm thick. Mohs surgery The indications for Mohs micrographic surgery have been widely expanded in recent years. The American Academy of Dermatology has now recognized Mohs micrographic surgery as a useful technique for the treatment of melanoma, particularly of the face. The National Institutes of Health also recognizes Mohs surgery as a potentially useful technique for melanoma. However, in its 1997 Melanoma Surgical Practice Guidelines, the Society of Surgical Oncology maintains that Mohs surgery is inappropriate for the treatment of melanoma. In 1997, Zitelli et al showed that the 5-year survival and metastatic control rates for Mohs surgery were equivalent to or better than rates in matched historical controls treated with wide local excision. Using the Mohs technique, the authors were able to spare normal tissue because 83% of the tumors were excised with a 6-mm margin. |
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Elective dissection of the lymph nodes For most solid tumors, including cutaneous malignant melanoma, the most powerful predictor of survival is the status of the regional lymph nodes. As the understanding of the tumor biology of malignant melanoma continues to evolve, the traditional role for lymphadenectomy in the evaluation and management of the regional nodes at risk has been challenged. For the patient with clinical evidence of regional nodal metastases at presentation, lymph node dissection with treatment of the primary lesion is appropriate. The procedure can often be selective neck dissection to remove the specific lymphatic sites involved with disease because of the tendency of regional melanoma metastases to grow in a pushing rather than an invasive fashion. For clinically evident, extensive regional metastases in the neck, comprehensive neck dissection is appropriate. The site of the primary lesion must be considered when neck dissection is planned to remove the intervening lymphatic drainage to the suspicious or positive node. The primary site must also be considered when one plans elective lymph-node dissection (ELND) for clinically negative necks. For primary lesions involving the parietal or frontal scalp, temple, lateral forehead, lateral cheek, or ear, superficial parotidectomy in conjunction with neck dissection is appropriate because the parotid may harbor the primary echelon nodes. For a primary lesion on the scalp posterior to a line drawn from the tragus to the vertex of the scalp, posterior-lateral neck dissection, which includes the postauricular, suboccipital, external jugular, and posterior triangle nodal groups, is appropriate. For the patient with an unknown primary lesion with evidence of neck nodal disease, a level I-V comprehensive neck dissection is appropriate. Notable controversy arises in the treatment of the clinically negative nodal basin. For thin (<0.75 mm) melanomas, the risk of occult lymphatic metastases is sufficiently low that prophylactic neck dissection is unwarranted. Patients with thick (>4.0 mm) melanomas have a poor prognosis, and prophylactic neck dissection does nothing to alter that prognosis. The strongest support for elective treatment of the clinically negative nodal basin is for melanomas of intermediate thickness (0.75-4.00 mm). Several retrospective studies have shown a possible survival benefit for elective treatment of the clinically negative nodal basin, but data from 2 large prospective multicenter trials did not show such an advantage. The Intergroup Melanoma Trial was the first prospective randomized trial to show a survival benefit in a subset of patients with melanoma treated with elective node dissection. Until recently, a strong argument could be made for the wait-and-see approach to the clinically negative nodal basin because of the morbidity of dissection without a clear survival benefit. Results of the Eastern Cooperative Oncology Group trial (ECOG EST 1684) of high-dose interferon (IFN) alfa-2b as adjuvant treatment for high-risk melanomas indicated that elective nodal dissection should not be delayed until disease is clinically detectable. In this randomized prospective trial, the relapse-free survival and overall survival rates improved in patients treated with IFN alfa-2b versus controls subjects. Striking differences were noted in a small subset of patients who had occult nodal metastases treated with IFN versus control. Data from this trial strongly supports an elective nodal staging procedure in all patients with intermediate-thickness malignant melanoma. Biopsy of sentinel lymph nodes The concept of the sentinel lymph node (SLN), as Morton first described it, has emerged as a potential solution to the debate over elective node dissection (Morton, 1993). The SLN is the first node in the drainage pattern of a tumor. After malignant cells pass through the SLN, they can then pass to second-echelon nodes. Therefore, by sampling the SLN, the surgeon can detect the earliest evidence of regional disease in the clinically negative nodal basin. The techniques of biopsy and examination of the SLN have evolved rapidly over the past few years. In essence, radioactive material and/or blue dye is injected at the periphery of the tumor, and preoperative lymphoscintigraphy and an intraoperative handheld gamma probe are used to locate the first node or nodes draining the tumor. These nodes are then sent for pathologic evaluation. Patients with pathologically positive SLNs next receive therapeutic nodal dissection. The technique of intraoperative lymphatic mapping and SLN biopsy are a highly sensitive surrogate that reflects the histologic status of the entire nodal basin. With the combination of lymphoscintigraphy with blue dye and a gamma probe, SLN biopsy has a success rate of over 90% with a false-negative rate of 2% or less. The technique of SLN biopsy has many potential advantages over ELND. First, preoperative lymphoscintigraphy is used to identify all nodal basins involved in the drainage of the primary site, whereas ELND has traditionally been directed at the most likely site of nodal drainage. In several studies, lymphoscintigraphy revealed that many tumors drain more than a single basin or that it can drain basins that were not predicted, particularly those in rich lymphatic areas, such as the head and neck. Nodal dissection can be misdirected in up to 50% of the cases. The use of preoperative lymphoscintigraphy helps avoid these misdirected nodal dissections. A second advantage of SLN biopsy over ELND is that an average of 1-2 nodes rather than an entire nodal basin are sampled with SLN biopsy. This feature allows more thorough examination of those nodes for evidence of metastatic disease with SLN biopsy than with ELND. Typical examination of a lymph node involves the staining of 1-2 sections through the middle of the node with routine hematoxylin and eosin; with this technique, less than 1% of the submitted material is examined. This technique can be used to detect 1 tumor cell in the background of 1000 healthy cells. Newer techniques have been developed that increase the sensitivity of tumor cell detection. These include immunohistochemical techniques, cell culture, and polymerase chain reaction (PCR)–based techniques that increase sensitivity up to 1 tumor cell in 100,000 healthy cells, an increase of 2 magnitudes. These sophisticated methods are too costly and labor intensive to be routinely applied to the entire contents of a lymphatic basin. The third advantage of SLN biopsy is that it targets the most likely node in a basin to reflect metastatic disease. This feature, combined with the above-mentioned pathologic techniques, provides surgeons with the most accurate information for prognosis and staging. This information is of particular advantage in planning for adjuvant therapy. The fourth advantage is that the SLN biopsy technique has less morbidity than ELND. With the addition of lymphoscintigraphy and intraoperative gamma-probe localization to the blue dye technique, the precise location of the node can usually be identified in 3 dimensions to within 1 cm. The node can then be removed through a skin incision that often is shorter than 1 cm, typically on an outpatient basis. SLN biopsy in the head and neck Four articles specifically addressing SLN biopsy for malignant melanoma of the head and neck region have been published. These papers present convincing evidence that this technique is accurate for the detection of melanoma metastases in the head and neck. The data strongly support the accuracy of SLN biopsy for the evaluation of the nodal basin in malignant melanoma of the head and neck. The success of localizing the SLN was 90% or better in all 4 articles. With the use of blue dye plus the gamma probe, 3 studies had success rates of 95% or better. The rate of tumor-containing SLN was 11-17%, with a 0% false-negative rate. Therefore, this strategy can apparently help more than 80% of patients to avoid neck dissection. More long-term studies must be carried out to evaluate whether these data have any prognostic importance in melanoma of the head and neck. However, these data show that the SLN theory applies to the head and neck region.
Chemotherapy has yielded poor results. No single agent has a >25% response rate, and even multiagent chemotherapy rarely yields a response rate >40%. Immunotherapy trials have shown encouraging results in the adjuvant treatment of melanoma (see ECOG Trial EST 1684); however, the long-term ramifications of IFN alfa-2b therapy are unknown. Many other vaccination and immunomodulation agents, such as bacille Calmette-Guérin (BCG) and recombinant interleukin-2 (rIL-2), are being tried experimentally. Although melanoma has traditionally been considered a radiation-resistant tumor, data from recent trials show that external-beam radiation may be valuable as an adjuvant therapy for melanoma. For patients with evidence of multiple positive lymph nodes or those with extracapsular spread, postoperative radiation therapy after neck dissection is appropriate. Radiation can also be used to palliate metastatic disease. However, surgery remains the primary treatment modality for most localized melanomas.
The incidence of melanoma of the head and neck has been increasing dramatically in the last several decades. Much of this change is related to increased sun exposure in the general population.
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