Melanoma is a malignant
tumor that arises from melanocytic cells and primarily involves the skin. The most important exogenous etiological factor is exposure to ultraviolet irradiation. Diagnosis of
melanoma is based primarily on its clinical features, and the A-B-C-D rule is useful in identifying pigmented lesions, which are suspicious for
melanoma (Asymmetry, Border irregular, Color inhomogeneous and Diameter more than 5 mm). Dermoscopy is very helpful in clarifying the differential diagnosis of pigmented lesions. About 90% of
melanomas are diagnosed as primary
tumors without any evidence for
metastasis. The
tumor-specific 10-year survival for all such
tumors is about 75-85%. The most important prognostic factors for primary
melanoma without
metastases are vertical
tumor thickness (Breslow depth) as measured on the histological specimen, presence of histopathologically recognized ulceration, invasion level (Clark level) and identification of
micrometastases in the regional lymph nodes via sentinel lymph node biopsy. The current
tumor node
metastasis classification for the staging of primary
melanoma is based on these factors.
Melanomas can metastasize either by the lymphatic or by the hematogenous route. About two-thirds of
metastases are originally confined to the drainage area of regional lymph nodes. A regional
metastasis can appear as satellite
metastases up to 2 cm from the primary
tumor, as intransit
metastases in the skin between the site of the primary
tumor and the first lymph node and as regional
lymph node metastases. In the stage of regional
metastasis, the differentiation between
micrometastasis and macrometastasis and the number of lymph nodes involved are crucial. As soon as distant
metastasis develops, prognosis depends on the site of the
metastasis and on the
lactate dehydrogenase levels in the blood. The frequency and extent of follow-up examinations is based on the initial
tumor parameters. In thin primary
melanomas up to 1-mm
tumor thickness, clinical examinations at 6-month intervals are sufficient and in thicker primary
melanomas, at 3-month intervals. Lymph node sonography as well as determination of the
tumor marker protein S100beta are recommended. Additionally, in the stage of regional
metastasis, whole body imaging should be performed every 6 months; in the stage of distant
metastasis, surveillance has to be scheduled individually.