Evidence and interdisciplinary consense-based German guidelines: diagnosis and surveillance of melanoma
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 S100β 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.