Lymph proteins may access peripheral blood without entering thoracic duct in patients with lymphatic dysfunction.

OBJECTIVE

The objective was to investigate the hypothesis that lymphovenous communications, which allow lymph proteins to access peripheral blood without first entering the thoracic duct, open in patients with abnormal lymphatic function.

METHODS

Routine lymphoscintigraphy of 182 patients, including 27 without clinical evidence of lymphedema (controls), was performed immediately and 45 and 150 minutes after subcutaneous injection of technetium Tc 99m nanocolloid into both feet. Counts per pixel in a region of interest over the liver (L) were divided by total counts in bilateral ilioinguinal nodes (N) at 45 minutes (L/N45) and 150 minutes (L/N150). If all activity leaving ilioinguinal lymph nodes entered the thoracic duct, these L/N ratios would be similar from patient to patient.

RESULTS

Eight patients were excluded because of immediate liver activity suggesting inadvertent intravascular injection of tracer. In controls (group 1), L/N150 displayed a normal distribution with mean (± standard deviation) of 0.16 (0.09) × 10(-4) pixels(-1). Patients with L/N150 >0.34 × 10(-4) pixels(-1) (ie, 0.16 + 2 standard deviations) were assumed to have lymphovenous communications. Of 34 patients with clinical evidence of lymphedema but with normal findings on lymphoscintigraphy (group 2), 3 (9%) had lymphovenous communications; of 114 with abnormalities on lymphoscintigraphy (group 3), 43 (38%) had lymphovenous communications (P = .001). N45/150 was significantly higher than L45/150 in all four groups, indicating arrival of activity in nodes before the liver. Abnormal features of lymphoscintigraphy-lymph transport delay, popliteal node visualization, and diversion of lymph through the skin-showed no association with L/N ratios.

CONCLUSIONS

Lymphovenous communications exist in about one-third of patients with abnormalities detected on lymphoscintigraphy. The timings of tracer arrival in the liver and lymph nodes is consistent with lymphovenous communication within lymph nodes themselves.