You are in: eMedicine Specialties > Plastic Surgery > SKIN Skin Malignancies, MelanomaArticle Last Updated: Nov 17, 2006AUTHOR AND EDITOR INFORMATIONAuthor: Jonathan B Heistein, MD, Private Practice, Plastic and Reconstructive Surgery Jonathan B Heistein is a member of the following medical societies: Alpha Omega Alpha, American Society of Plastic Surgeons, Texas Medical Association, and Texas Society of Plastic Surgeons Coauthor(s): Robert L Ruberg, MD, Chair, Professor, Department of Surgery, Division of Plastic Surgery, Ohio State University College of Medicine Editors: Shahin Javaheri, MD, Chief, Department of Plastic Surgery, Martinez Veterans Affairs Outpatient Clinic; Consulting Staff, Advanced Aesthetic Plastic & Reconstructive Surgery; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jorge I de la Torre, MD, FACS, Professor of Surgery and Physical Medicine and Rehabilitation, Residency Program Director, Division of Plastic Surgery, University of Alabama at Birmingham; Director, Center for Advanced Surgical Aesthetics; Nicolas (Nick) G Slenkovich, MD, Practice Director, Colorado Plastic Surgery Center at Swedish Medical Center; Jorge I de la Torre, MD, FACS, Professor of Surgery and Physical Medicine and Rehabilitation, Residency Program Director, Division of Plastic Surgery, University of Alabama at Birmingham; Director, Center for Advanced Surgical Aesthetics Author and Editor Disclosure Synonyms and related keywords: skin malignancy, malignant melanoma, skin cancer, melanocytes, lentigo maligna melanoma, benign melanocytic nevi, benign melanocytic nevus, melanocytic nevi, melanocytic nevus, dysplastic nevi, dysplastic nevus, superficial spreading melanoma, nodular melanoma, acral lentiginous melanoma, mucosal lentiginous melanoma, desmoplastic melanoma, verrucous melanoma, sunburn INTRODUCTIONHistory Melanoma is a tumor that develops as a result of the malignant transformation of melanocytes. These cells are derived from the neural crest. Melanomas usually occur on the skin but can arise in other locations where neural crest cells migrate, such as in the gastrointestinal tract or brain. Melanoma predominantly affects adults, with a peak incidence in the fourth decade, and has no sex prevalence. A patient's risk of developing a second primary melanoma after diagnosis of the first one is 3-5%. Definition of problem Melanoma poses an increasingly difficult problem as more people are affected. The incidence is estimated to be rising by almost 6% per year. Recognition of this disease as an entity is crucial so that people may seek medical attention while the tumor is still in its early stages, prior to metastasis. Efforts should be directed toward public awareness campaigns. Frequency In the United States, the incidence of melanoma continues to increase, with the prevalence of trunk and extremity lesions rising relatively faster than that of head and neck lesions; however, survival rates are improving. An estimated 34,100 people developed melanoma in the United States in 1995, with 7,200 deaths. This is an increase from the 27,600 new cases in 1990 and the 6,300 deaths. Furthermore, approximately 44,200 new melanoma diagnoses were made in 1999, and approximately 7,300 deaths were reported. An estimated 59,580 new cases of melanoma will occur in the United States in 2005, with 7,770 deaths. Currently, approximately 1 in 55 men and 1 in 82 women born in the United States develops melanoma at some point in his or her lifetime. Internationally, incidence varies worldwide. White populations in Australia, New Zealand, South Africa, and the southern United States have the highest rates, while Asian populations in Hong Kong, Singapore, China, India, and Japan have the lowest rates. This suggests that whites who live in sunny areas are at significant risk. Etiology/risk factors
Pathophysiology Some researchers have suggested that benign melanocytic nevi are markers of melanoma risk rather than direct precursors; however, dysplastic nevi are believed to degenerate over time into melanoma. Lentigo maligna is believed to be a preinvasive precursor of lentigo maligna melanoma, and at least 5% progress to malignancy. Clinical presentation Patients usually present with skin lesions that have changed in size, color, contour, or configuration. The acronym "ABCDE" is the hallmark of international public awareness campaigns and may be used to remember the physical characteristics suggestive of malignancy. ABCDE stands for asymmetry, irregular border, color variations (especially red, white, and blue tones in a brown or black lesion), diameter greater than 6 mm, and elevated surface. Lesions may itch, bleed, ulcerate, or develop satellites. Perform excisional biopsy on these suggestive lesions so that a pathologist can confirm the diagnosis. Shave biopsies and electrodesiccation are inadequate; a full thickness of skin is essential for proper histologic diagnosis and classification. The most important prognostic indicator for stage I and II tumors is thickness; obtain a full-thickness biopsy specimen for adequate pathologic interpretation. Biopsy results ultimately determine the margins of resection and which patients are candidates for sentinel lymph node biopsy and other adjuvant treatment. Patients who present with metastatic disease or with primary sites other than the skin have signs and symptoms related to the affected organ system(s). INDICATIONS AND GUIDELINESPerform biopsy on all lesions suggestive of melanoma; sample the thickest part of the lesion. Maintain a low threshold to perform biopsy because the procedure is easy and safe. If the resection will not result in a disfiguring defect, excisional biopsy with a 2-mm skin margin and extension to the subcutaneous tissue is suggested for lesions less than 1.5 cm in diameter. Take care to leave scars in locations where re-excision is not difficult. If the lesion is large or located in an anatomic area where skin removal would cause disfigurement, an incisional biopsy may be performed. A full-thickness core punch biopsy in the most raised or irregular area is suggested, with the understanding that this area may not be the thickest area. Contraindications Biopsy of a suggestive lesion has no contraindications. Even with widely metastatic melanoma, local control can be attempted. RELEVANT ANATOMYThe skin is composed of multiple layers. The epidermis is the most superficial layer, and it contains keratinocytes in various stages of development. Melanocytes are located in the deepest layer of the epidermis. A basement membrane separates the epidermis from the underlying dermis, which is divided into 2 zones, papillary dermis and reticular dermis. Subcutaneous tissue is deep to the reticular dermis. In 1874, Sappey performed an anatomic study of cutaneous lymphatic drainage, which is the foundation for current knowledge of this subject. Sappey's results demonstrated the lymphatic drainage based on anatomic location. His findings were modified later, but then the advent of lymphoscintigraphy led to more accurate lymphatic mapping. Norman et al then redefined the lymphatic basins in a definitive report. They concluded that an extensive overlap of basins drains the head, neck, shoulders, and trunk and that a specific basin cannot be predicted based on cutaneous location. Perform lymphoscintigraphy to define the exact lymphatic drainage for each patient. HISTOLOGIC CLASSIFICATIONMelanomas are classified into 4 major types based on growth pattern. They are superficial spreading melanoma, nodular melanoma, lentigo maligna melanoma, and acral lentiginous melanoma. Other more unusual types include mucosal lentiginous melanoma, desmoplastic melanoma, and verrucous melanoma. Superficial spreading melanoma Superficial spreading melanomas constitute approximately 70% of melanomas. Histologically, the characteristic cells can be present singly or in nests along the dermal-epidermal junction, but they also may migrate into the stratum granulosum or stratum corneum. These cells can invade the papillary dermis with an inflammatory lymphocytic infiltrate. Clinically, they usually arise in a preexisting dysplastic nevus. Typically, this lesion changes slowly over several months to years. They are usually flat but may become irregular and elevated in later stages. The lesions average 2 cm in diameter with variegated colors and peripheral notches, indentations, or both. Nodular melanoma Histology of nodular melanomas is characterized by extensive vertical growth into the dermis with a minimal radial component. They comprise approximately 15-30% of melanoma diagnoses. These tumors typically are blue-black but may lack pigment in some circumstances. They are known to arise without a preexisting lesion. Lentigo maligna melanoma Lentigo maligna melanomas represent 4-10% of melanomas. On a cellular level, dermal and epidermal changes from sun exposure must be present. The histologic appearance is one of irregularly shaped hyperchromatic cells that form spindle-shaped nests. The epidermis is atrophic, while the dermis contains solar elastosis with chronic inflammatory infiltrates. From a clinical standpoint, lentigo maligna melanomas are often larger than 3 cm, flat, tan, and begin as small, frecklelike lesions. They occur in sun-exposed areas (eg, face and neck of older individuals). Marked notching of the borders is present. Lentigo maligna melanoma usually arises within a Hutchinson freckle (lentigo maligna). When tumor thickness and location are taken into consideration, the prognosis for these melanomas is not believed to be worse than that for other subtypes. Acral lentiginous melanoma This tumor comprises 2-8% of melanomas in whites and 35-60% of melanomas in dark-skinned people. Cellular proliferation is present along the dermal-epidermal junction with microinvasion into the papillary dermis. The cells have increased melanin granule production, which fills their dendritic extensions. Acral lentiginous melanomas occur on the palms of the hands, beneath the nail beds, and on the soles of the feet. They may appear on the palms and soles as flat, tan, or brown stains with irregular borders. Subungual lesions can be brown or black, with ulcerations in later stages. No correlation with a worse prognosis is demonstrated for these lesions when tumor thickness is considered. Desmoplastic melanoma These lesions account for approximately 1% of melanoma cases; they are fairly rare. They demonstrate a tendency for perineural invasion, especially in the head and neck. They have a propensity for higher local recurrence rates but lower regional metastasis rates. CLASSIFICATION AND STAGINGTwo classification schemes have been developed, based on either the vertical thickness of the lesion in millimeters or the anatomic level of invasion of the layers of skin. The Breslow classification scheme is used almost exclusively now because it more accurately predicts future tumor behavior. The Clark level is now used only in the staging of thin (T1) melanomas. The TNM (tumor, node, metastasis) system is used for clinical staging as designated by the American Joint Committee on Cancer (AJCC) staging system.
TREATMENTMedical TherapyMedical therapy is of questionable value; use it as adjuvant treatment in advanced stages. Surgical TherapySurgical therapy for melanoma is based on the predicted risk of local recurrence and metastatic disease and the potential morbidity of the operation. If the lesion has not spread beyond the primary site, it is potentially curable. Most of these lesions are thin ( <1 mm or CL I or II). Stage 0 After making the diagnosis, widely excise the tumor or previous biopsy site. Use a 0.5- to 1-cm margin for melanomas in situ. No further therapy other than observation for nodal or recurrent disease is necessary. Stage I For a T1 lesion, 1-cm excision margins are adequate, but lesions greater than 1 mm require 2-cm margins. Studies demonstrate no improvement in recurrence or survival rates with larger margins of resection. Attempt primary closure and perform skin grafting or flap closure if necessary. For lesions with a depth greater than 1 mm, many authorities recommend sentinel lymph node biopsy at the time of wide local excision (see Stage II below). Stage II Perform a 2-cm surgical resection on stage II lesions. No recurrence or survival advantage is gained when 2-cm margins are compared with wider margins (4-6 cm). Smaller resection decreases the need for skin grafting and inpatient hospital stay. Perform a complete therapeutic lymphadenectomy on patients with suspected lymph node metastases based on physical examination findings. This consists of excision of all lymph nodes in the affected regional lymph node basin. Consider sentinel lymph node biopsy if no clinically positive nodes are present. With the use of blue dye, radioisotope, or both, injected at the site of the primary melanoma, the first-echelon node can be identified within the regional lymph node basin. Send this sentinel node to the pathologist for analysis using routine stains, immunohistochemistry, and even polymerase chain reaction in some centers. If the sentinel node is positive, then regional lymph node metastases is probable; importantly, perform a complete lymph node dissection. The correlation is based on the thickness of the primary tumor. If the sentinel lymph node is negative, the chance is 99% that all others are negative. This procedure is becoming the standard of care for tumors greater than 1 mm in depth. Hyperthermic arterial limb perfusion with melphalan for extremity melanomas has been studied as an adjuvant therapy. One study found it to be beneficial in that it produced higher response rates and overall survival rates than those for surgery alone. Other studies do not demonstrate benefit. Adjuvant chemotherapy and/or biological therapy are also undergoing clinical evaluation. One study demonstrated that high-dose interferon alfa-2b resulted in prolonged relapse-free survival and overall survival compared with no adjuvant therapy. A follow-up study by the same group demonstrated preliminary results indicating high-dose interferon achieved a relapse-free survival benefit over no adjuvant treatment but not over low-dose interferon. Neither high- nor low-dose interferon had a significant overall survival advantage compared with observation alone. High-dose interferon can be associated with significant toxic/adverse effects (ie, liver toxicity), and some patients require dose reduction because it may not be well tolerated. Stage III Wide local excision of the primary tumor with 2-cm margins remains first-line therapy. No survival advantage is demonstrated with wider resection margins. Skin grafting or other tissue-transfer techniques may be necessary to close the defect. Perform regional lymph node dissection because a stage III melanoma represents nodal disease. If the nodal status is unknown, consider a sentinel lymph node biopsy to determine if the disease is stage I, II, or III. As in stage II disease, the treatment failure rate is higher with wide local excision alone in this group compared with stages 0 and I. Many clinical trials currently are exploring similar options as adjuvant therapy. Stage IV Advanced metastatic melanoma is usually refractory to standard therapy; thus, consider these patients for clinical trials. Some treatments have yielded various objective responses, although they are usually short-lived. Dacarbazine (DTIC) and the nitrosoureas, carmustine (BCNU) and lomustine (CCNU), produced a 20% objective response rate. Response rates for interferon alfa and interleukin 2 range from 8-22% and 10-20%, respectively. Currently, other studies in progress are comparing other cytotoxic and biologic drug regimens. Surgical resection of isolated metastases in the gastrointestinal tract, the brain, the lungs, or bone may be performed for palliation, with occasional long survival. Metastatic lymph nodes also may be removed for palliation. Radiation may provide symptomatic relief for metastases to bone, the brain, or viscera. In-transit metastases arise in the lymphatics or soft tissue between the primary lesion and the regional lymph node basin at a rate of 2-3%. In addition to wide surgical excision as for a primary lesion, isolated hyperthermic limb perfusion is probably the most effective treatment for extremity lesions. Radiation and intralesional BCG vaccine injections have had varied success. Recurrent melanoma Surgical excision offers the most efficacious results in sites where it can be accomplished; however, melanoma is usually refractory to most standard systemic therapy. Preoperative DetailsEvaluate for metastases. Begin this evaluation with a detailed history and physical examination. The most common metastatic sites, in descending order, are the regional lymph nodes, skin and subcutaneous tissue (in-transit lesions), and lungs. Other possibilities include the brain, the liver, and bone. In the absence of signs or symptoms of metastatic disease after performing the history and physical examination, obtain a chest radiograph. If abnormalities are observed, follow this with a chest CT scan. Check serum alkaline phosphatase and lactate dehydrogenase levels. If these are abnormal or if the patient has a history of weight loss, anorexia, or abdominal pain, obtain a liver ultrasound, abdominal CT scan, or both. Any abnormalities in the neurologic examination or a history of headaches, vertigo, numbness, or weakness warrant a head CT scan. A bone scan also may be indicated for isolated bone pain or an elevated alkaline phosphatase level. Use lymphoscintigraphy to identify the correct lymph node basin(s) that drain the site of the primary tumor. This is an essential aid in preoperative planning. Intraoperative DetailsWhen performing the wide local excision, first consider the surgical margins. If primary closure is not feasible, skin grafting or tissue transfers may be needed. The use of blue dye and radiotracer together provides excellent results and is sensitive in finding the sentinel lymph node. Frozen section specimens have largely been abandoned because the process destroys the ability to analyze the node using immunohistochemistry. Postoperative DetailsSend the lesion and lymph node specimens to experienced pathologists for review. After the primary tumor is evaluated, the lymph node(s) should undergo hematoxylin and eosin staining. If findings are negative for melanoma, use immunohistochemical techniques. Specific staining for S-100 protein and HMB-45 monoclonal antibody increases the detection of lymph node micrometastases. More elaborate techniques using reverse transcriptase polymerase chain reaction are still investigational. They can detect the tyrosinase gene, which is specific for the melanocyte. Follow-up careClose follow-up care is essential to monitor for new primary lesions, recurrence, or metastases. History and physical examination are the cornerstones, with further testing (eg, chest radiography, blood chemistries) if suggestive findings are encountered. Most practitioners observe patients every 3-6 months initially and then eventually decrease the frequency, although no consensus exists. Physicians observe patients with thicker tumors more frequently than patients with thinner lesions. Follow-up care with a dermatologist is strongly recommended. Educate patients on self-examination for detection of new or recurrent lesions and for recognition of the signs and symptoms of metastatic disease because the risk of developing a second melanoma or having recurrence is well recognized. For excellent patient education resources, visit eMedicine's Cancer and Tumors Center and Procedures Center. Also, see eMedicine's patient education articles Skin Cancer, Skin Biopsy, and Mole Removal. COMPLICATIONS, PROGNOSIS, AND OUTCOMEComplications Inability to close the excision site primarily is not truly a complication; however, wound dehiscence, skin necrosis, or both can occur from closure under tension. Wound infection is a potential complication. Seromas and lymphoceles occur up to 27% of the time with axillary node dissection, while nerve dysfunction and/or pain can occur 22% of the time, and hematoma can occur 1% of the time. Lymphedema of the upper and lower extremities can complicate axillary and groin lymph node dissections. The rates vary from 2-39%. Avoid incomplete resection at all costs. Careful preoperative evaluation and meticulous attention to detail intraoperatively should help minimize the risk of these complications. Poor prognostic factors include the following:
Outcome The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Relative survival rates take into consideration the fact that people may die of other causes besides melanoma. With relative rates, anyone who died of another cause, such as heart disease, is not counted. This is considered to be a more accurate way to describe the prognosis for people with particular types and stages of cancer. Of course, 5-year survival rates are based on patients diagnosed and initially treated more than 5 years ago. Improvements in treatment often result in a more favorable outlook for recently diagnosed patients.
In a study from Alabama, patients with 1, 2-4, or more than 4 positive node(s) had survival rates of 58%, 27%, and 10%, respectively. Patients with spread to the lymph nodes have an 85% chance of developing occult disease. The worst outcome is predicted for patients with distant metastasis (stage IV). With a single metastatic site, the 1-year survival rate is 36%, but this drops to 13% with 2 sites. Patients with 3 or more sites of metastatic disease essentially have a 0% survival rate in the first year. These rates all vary somewhat according to the prognostic characteristics (see Prognosis). FUTURE AND CONTROVERSIESThe continuation of clinical trials to search for beneficial chemotherapy, gene therapy, biologic therapy, immunotherapy, and other adjunctive procedures is necessary to improve the prognosis for patients with melanoma. This is especially important as the number of patients continues to rise. As with all disease, methods for early detection in addition to careful physical examination are of utmost concern. Reverse transcriptase polymerase chain reaction currently is undergoing evaluation on a prospective basis in the national multicenter Sunbelt Melanoma Trial. Continued searches for serum markers and genetic markers are also essential. Creation of a successful public awareness campaign, such as those in Australia and New Zealand, is crucial. MULTIMEDIA
REFERENCES
Skin Malignancies, Melanoma excerpt Article Last Updated: Nov 17, 2006 | |||||||||||||||||||||