A malignant neoplasm that arises from melanocytes, malignant melanoma is relatively rare and accounts for only 1% to 2% of all malignancies. However, the incidence is greatly increasing with a noted 300% increase in the past 40 years. The four types of melanomas are superficial spreading melanoma, nodular malignant melanoma, lentigo maligna, and acral lentiginous melanoma.
Melanoma spreads through the lymphatic and vascular systems and metastasizes to the regional lymph nodes, skin, liver, lungs, and central nervous system (CNS). Its course is unpredictable, however, and recurrence and metastasis may not appear for more than 5 years after resection of the primary lesion. The prognosis varies with tumor thickness. Generally, superficial lesions are curable, whereas deeper lesions tend to metastasize. The Breslow level method measures tumor depth from the granular level of the epidermis to the deepest melanoma cell. Melanoma lesions less than 0.76 mm deep have an excellent prognosis, whereas deeper lesions (more than 0.76 mm) are at risk for metastasis. The prognosis is better for a tumor on an extremity (which is drained by one lymphatic network) than for one on the head, neck, or trunk (drained by several networks).
Several factors seem to influence the development of melanoma:
❑Excessive exposure to sunlight — Melanoma is most common in sunny, warm areas and usually develops on parts of the body that are exposed to the sun.
❑ Skin type — Most persons who develop melanoma have blond or red hair, fair skin, and blue eyes; are prone to sunburn; and are of Celtic or Scandinavian ancestry. Melanoma is rare among Blacks; when it does develop, it usually arises in lightly pigmented areas (the palms, plantar surface of the feet, or mucous membranes).
❑ Hormonal factors — Pregnancy may increase risk and exacerbate growth.
❑ Family history — Melanoma is slightly more common within families.
❑ Past history of melanoma — A person who has had one melanoma is at greater risk of developing a second.
Melanoma is slightly more common in women than in men and is rare in children. Peak incidence occurs between ages 50 and 70, although the incidence in younger age-groups is increasing.
Common sites for melanoma are on the head and neck in men, on the legs in women, and on the backs of persons exposed to excessive sunlight. Up to 70% arise from a preexisting nevus. It rarely appears in the conjunctiva, choroid, pharynx, mouth, vagina, or anus.
Suspect melanoma when any skin lesion or nevus enlarges, changes color, becomes inflamed or sore, itches, ulcerates, bleeds, undergoes textural changes, or shows signs of surrounding pigment regression (halo nevus or vitiligo). (See Recognizing potentially malignant nevi, page 134.)
Each type of melanoma has special characteristics:
❑Superficial spreading melanoma, the most common, usually develops between ages 40 and 50. Such a lesion arises on an area of chronic irritation. In women, it's most common between the knees and ankles; in Blacks and Asians, on the toe webs and soles (lightly pigmented areas subject to trauma). Characteristically, this melanoma has a red, white, and blue color over a brown or black background and an irregular, notched margin. Its surface is irregular, with small, elevated tumor nodules that may ulcerate and bleed. Horizontal growth may continue for many years; when vertical growth begins, prognosis worsens.
❑Nodular melanoma usually develops between ages 40 and 50, grows vertically, invades the dermis, and metastasizes early. Such a lesion is usually a polypoidal nodule, with uniformly dark discoloration (it may be grayish), and looks like a blackberry. Occasionally, this melanoma is flesh-colored, with flecks of pigment around its base (possibly inflamed).
❑Lentigo maligna melanoma is relatively rare. It arises from a lentigo maligna on an exposed skin surface and usually occurs between ages 60 and 70. This lesion looks like a large (3- to 6-cm) flat freckle of tan, brown, black, whitish, or slate color and has irregularly scattered black nodules on the surface. It develops slowly, usually over many years, and eventually may ulcerate. This melanoma commonly develops under the fingernails, on the face, and on the back of the hands.
A skin biopsy with histologic examination can distinguish malignant melanoma from a benign nevus, seborrheic keratosis, and pigmented basal cell epithelioma; it can also determine tumor thickness. Physical examination, paying particular attention to lymph nodes, can point to metastatic involvement. (See Staging malignant melanoma, page 135.)
Baseline laboratory studies include complete blood count with differential, erythrocyte sedimentation rate, platelet count, liver function studies, and urinalysis. Depending on the depth of tumor invasion and metastatic spread, baseline diagnostic studies may also include chest X-ray and a computed tomography (CT) scan of the chest and abdomen. Signs of bone metastasis may call for a bone scan; CNS metastasis necessitates a CT scan of the brain.
A patient with malignant melanoma requires surgical resection to remove the tumor. The extent of resection depends on the size and location of the primary lesion. Closure of a wide resection may require a skin graft. Surgical treatment may also include regional lymphadenectomy.
Deep primary lesions may merit adjuvant chemotherapy and biotherapy to eliminate or reduce the number of tumor cells. Clinical trials are currently under way to evaluate the effectiveness of isolated limb perfusion as chemotherapy for the management of malignant melanomas of extremities. Radiation therapy is usually reserved for metastatic disease. It doesn't prolong survival but may reduce tumor size and relieve pain.
Regardless of the treatment method, melanomas require close long-term follow-up to detect metastasis and recurrences. Statistics show that 13% of recurrences develop more than 5 years after primary surgery.
Management of the melanoma patient requires careful physical, psychological, and social assessment. Preoperative teaching, meticulous postoperative care, and psychological support can make the patient more comfortable, speed recovery, and prevent complications.
After diagnosis, review the physician's explanation of treatment options. Tell the patient what to expect before and after surgery, what the wound will look like, and what type of dressing he'll have. Warn him that the donor site for a skin graft may be as painful as the tumor excision site, if not more so. Honestly answer any questions he may have about surgery, chemotherapy, and radiation.
❑After surgery, be careful to prevent infection. Check dressings often for excessive drainage, foul odor, redness, or swelling. If surgery included lymphadenectomy, minimize lymphedema by applying a compression stocking and instructing the patient to keep the extremity elevated.
❑During chemotherapy, know what adverse effects to expect and take measures to minimize them. For instance, give an antiemetic, as ordered, to reduce nausea and vomiting.
To prepare the patient for discharge:
❑Emphasize the need for close follow-up to detect recurrences early. Explain that recurrences and metastasis, if they occur, are commonly delayed, so follow-up must continue for years. Tell the patient how to recognize signs of recurrence.
❑Provide psychological support. Encourage the patient to verbalize his fears.
In advanced metastatic disease:
❑Control and prevent pain with consistent, regularly scheduled administration of analgesics. Don't wait to relieve pain until after it occurs.
❑Make referrals for home care, social services, and spiritual and financial assistance, as needed.
❑If the patient is dying, identify the needs of the patient, his family, and friends, and provide appropriate support and care.
To help prevent malignant melanoma, stress the detrimental effects of overexposure to solar radiation, especially to fair-skinned, blue-eyed patients. Recommend that they use a sunblock or sunscreen. In all physical examinations, especially in fair-skinned persons, look for unusual nevi or other skin lesions.
Review other book chapters online related to Melanoma:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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