[Pathways of regional lymph node metastases originating from soft tissue sarcomas].

Lymph node metastases originating from soft tissue sarcomas are very rare and the reason for this is unclear. While this observation was less important in former times when ultraradical excision and amputation were the norm, modern reconstructive surgical treatment options have to take the possibility of lymphatic metastases into account.We attempted to identify parameters that may be predictive of lymphatic metastases in a cohort of 1,597 patients with soft tissue sarcomas of whom 26 patients (1.6  %) had regional lymph node (RLN) metastases. We studied these RLN metastases with recently described techniques that enabled us to histologically visualize lymphatic vessels.We conclude that sarcomas should not be evaluated from a histogenetic perspective but more on the basis of regional topography of the lymphatic vasculature. As we described previously, two different lymphatic systems should be differentiated: lymphatic vessel system I (LGS I) contains RLN and lymph vessels are mostly superficial; however, there are also vessels near large blood vessels of the extremities. System LGS II is more delicate and its vessels run into the musculature, a metastatic homing area of many sarcomas. Lymph vessels of system LGS II drain directly into veins without intervening lymph nodes. Sarcomas with LGS I drainage will form RLN metastases. In contrast, sarcomas with LGS II drainage will do so only after surgical resection if system LGS I has been opened.