Lymphoscintigraphic Evaluation of Systemic Tracer Uptake in Patients With Primary Lymphedema

Jeremy A. Goss, MD, Reid A. Maclellan, MD, MMSc, and Arin K. Greene, MD, MMSc. Ann Plast Surg 2019

Click to read the abstract

Lymphoscintigraphic Evaluation of Systemic Tracer Uptake in Patients With Primary Lymphedema

Jeremy A. Goss, MD, Reid A. Maclellan, MD, MMSc, and Arin K. Greene, MD, MMSc. Ann Plast Surg 2019

Background: Lymphoscintigraphy is used to confirm the diagnosis of lymphedema. One end point for the test is to ensure a patent thoracic duct by uptake of tracer in the organs. The purpose of this study was to evaluate transit of radiolabeled colloid to the organs to gain insight into the etiopathophysiology of primary lymphedema.

Methods: Patients treated in our Lymphedema Program between 2009 and 2018 were reviewed. Only subjects with bilateral lower extremity primary lymphedema were included (individuals with unilateral leg lymphedema were excluded because the tracer will reach the venous circulation and organs through the normal extremity). Disease severity and lymphoscintigraphy findings were documented.

Results: Sixty-one patients were included. Ten subjects had no radiolabeled tracer transit to the inguinal lymph nodes on lymphoscintigraphy. However, 8 of these individuals had tracer uptake to the liver, kidney, and/or bladder, illustrating clearance of tracer into the systemic venous circulation. All 8 patients had infant-onset primary lymphedema and mild disease. The 2 patients who did not have clearance of tracer to the systemic venous circulation developed lymphedema in adolescence and had clinically moderate or severe disease.

Conclusions: Patients with primary lower extremity lymphedema often have pathways for lymph fluid to reach the venous circulation other than through the inguinal nodes and thoracic duct. Documentation of systemic tracer uptake during lymphoscintigraphy to confirm a patent thoracic duct has limited clinical significance in subjects with primary disease of the legs.

Main findings

  • Bilateral lower extremity lymphedema was confirmed by lymphoscintigraphy. Lymphoscintigraphy was performed using Tc99m-labeled filtered sulfur colloid.
  • Fifty-one subjects had transit to the inguinal nodes during the study (eg, delayed transit of >45 minutes but reached the nodes by 2 hours.
  • 10 individuals had no transit to the inguinal nodes at the completion of the study, and thus, the tracer could not have reached the thoracic duct/systemic circulation through normal lymphatic pathways.
  • Eight subjects had uptake of tracer into organs (liver, kidney, and bladder), and these individuals had infant-onset lymphedema and mild disease.
  • Two patients had no systemic tracer uptake and had adolescent-onset and moderate or severe disease.
  • Although tracer injected into both feet did not reach the bilateral inguinal nodes, the tracer exhibited uptake into organs. Thus, alternative pathways likely exist for lymphatic fluid to reach the systemic venous circulation other than through the inguinal nodes and thoracic duct. All of these patients had the infant-onset disease and thus may have had embryologic lymphatic-venous connections in their legs. Lymphatics form developmentally from veins, and connections might remain in patients with primary lymphedema to compensate for the impaired proximal return of lymph fluid. Alternatively, these individuals may have developed secondary lymphatic-venous connections as a compensatory mechanism.
  • Veins also may have developed a lymphatic phenotype to allow the drainage of large proteins and fluid into the venous circulation.
  • Images were taken at 45 minutes and 2 hours.