[Lymph vascularity and lymph node metastases on PET and PET-CT: immunohistological and clinical observations].

Sarcomatous malignancies only rarely develop regional lymph node metastases: about 2.7% of our evaluated cases. In this paper we provide evidence supporting a new hypothesis that two entirely separate lymph vascular systems exist in humans. One system (LGS I) exists in close proximity to the epithelium and drains into regional lymph nodes. Only sarcomas that originate in the epithelium or its immediate proximity are able to form regional lymph node metastases. The vast majority of sarcomatous malignancies (97.4% of cases) do not give rise to lymph node metastases, since they originate in proximity to a second, more deeply localized lymph node system (LGS II) in the mesenchymally derived tissues of the body. This second system has no connection to regional lymph nodes. Supporting evidence is provided by experience in the operative treatment of extremity lymphedema, PET-CT examinations, radionuclear lymphography, and scientific investigations using antibodies specifically directed at the elements of the lymph vascular system.