Sylven,⁵ in 1949, suggested a very different system for analyzing patients with melanoma than that of Ackerman and Del Regato. His series consisted of 341 patients with melanoma who had been seen in Sweden between 1929 and 1943. In an article that appeared in Acta Radiologica, Sylven employed a system based on three tiers thus:

It is noteworthy that in the system of staging advocated by Sylven, as in that of others subsequently, metastases to regional lymph nodes are not regarded as being distant. This is curious for several reasons, not the least of which are that in a lower extremity the "regional lymph nodes" may be several feet from the primary melanoma in the skin and that a metastasis of any kind, no matter whether designated satellite, in transit, or regional, is an indication of metastases far and wide, that is, every metastasis is a signal of distant metastases. Numerous studies have shown that the lymph vascular and blood vascular circulations are intimately interconnected and, therefore, once neoplastic cells gain access to lymph they are given entry to blood, too. Why, then, were "deposits in cutaneous lymphatics" categorized as Stage 1 and judged to have the best prognosis, when, in actuality, the finding of neoplastic cells in lymphatics anywhere, including the skin, presages a grim prognosis. It is likely that discrepancies such as these led Sylven to conclude, erroneously, that radical surgery, including amputation of limbs with contiguous en bloc regional lymph node dissection, should be adopted for all cases of Stage II melanoma.