The prognosis and possible cause of severe primary lymphoedema.

We studied 372 patients with primary lymphoedema in order to predict the extent and severity of the disease. We found that the limits of oedema were defined early in the process and that the loss of distal lymphatics alone did not lead to severe oedema. Severe lymphoedema was associated with pelvic lymphatic 'obstruction' on lymphography and 26% of these patients eventually required surgery. Lymphography suggested that the 'obstruction' was related to lymph nodes and inguinal node biopsies were taken at the time of lymphography in 72 patients. In patients with pelvic lymphatic 'obstruction' we found a severe nodal fibrosis which was not apparent in those with distal lymphatic disease alone. This fibrosis was not related to episodes of cellulitis and since it was present in the early stages of the disease it is unlikely to be due to slow obliteration of distal lymphatics. Furthermore it could not be reproduced by ligating either afferent or efferent lymphatics of the rabbit popliteal lymph node. This suggests that severe primary lymphoedema may develop as a result of disease of the pelvic lymph nodes.