A new classification of malignant melanoma proposed according to the TNM-system.

A model of pretherapeutic classification of malignant melanoma is proposed in accordance to the TNM system. It differs principally from the melanoma classification issued by UICC in 1968 and withdrawn in 1974, in that a new category “R” is introduced for satellite and transit metastases, and that the T classification of the primary tumor contains not only the horizontal dimension, but the vertical elevation of the tumor above skin level. The new classification was tested in a retrospective study of 175 patients of the Hornheide Special Clinic. Clinical utility and relevance of the system could be documented. In the classification of primary tumor, the degree of elevation above skin level was found to correlate better with posttherapeutic prognosis of melanoma than the horizontal tumor diameter. The vertical dimension of a tumor is an indicator of its invasive potential and hence of the probability of metastatic spread. The pretherapeutic, purely clinical classification of melanoma cannot be meant to substitute histologic examination with its exact assessment of invasion etc. On the other hand, posttherapeutic definition of tumor levels by histology does not eliminate the necessity for correct pretherapeutic examination and macroscopic description of the tumor size in its three dimensions. Atraumatic assessment of tumor elevation with its implications plays an essential role in the planning of tumor therapy: In case of deep invasive melanoma, lymph node extirpation is indicated at the time of intraoperative examination of frozen sections of the primary. Experience has taught us that intraoperative examination may be hampered by considerable errors in determining the exact depth of an invasive growth, as frozen sections sometimes fail to give a clear picture of the largest tumor diameter. In such cases, clinical measuring of the tumor in its macroscopic appearance may serve as a rough guide for excision and histology.