Imaging Lymphatic Function of a Toddler with Congenital Lymphedema

Objectives Pediatric lymphedema is reported to occur in 1 in 6000 children and can differ from adult lymphedema in that it is typically of primary, non-traumatic origin and may not progress to pitting edema. Primary lymphedema in the pediatric population remains poorly diagnosed and misunderstood due to a lack of information on the causation and underlying anatomy of the lymphatic system. We sought to image the lymphatics in the extremities of a 21 month old boy who presented with unilateral right arm and hand lymphedema at birth.

Methods Based on an FDA(IND:102,827) and IRB-approved protocol, near-infrared fluorescence lymphatics imaging was offered to the patient’s family to elucidate the cause of his lymphedema. After informed consent of the parents, an intradermal injection, containing 12.5 µg of indocyanine green (ICG) in 0.05 ml saline, was administered in the dorsum of each foot and hand for lymphatic uptake, for a total dose of 50 µg. Image acquisition rates of about 88 images/minute enabled visualization of its transit through functional lymphatics. Imaging occurred on the unsedated child while he sat in his mother's lap.

Results The imaging results indicated an intact, apparently normal lymphatic anatomy with no obvious malformation but with decreased lymphatic contractile function of the affected right upper extremity relative to the contralateral and lower extremities. Movies show active propulsion in unaffected extremities. Figure 1 shows fluorescent images and movies of lymphatics in the (A) lateral and (B) medial right arm, and (C) axilla of the right arm. Figure (D) shows intact vessels with limited contractile function with possible dermal backflow near the right wrist. Manual lymphatci drainage techniques increased contractile function in the right arm. We hypothesize that the lack of contraction of the lymphatic vessels rather than an anatomical malformation is the source of the unilateral extremity swelling and that compression and manual lymphatic drainage could be effective treatments.

Conclusions Near-infrared fluorescence lymphatic imaging can provide information of malformation or inadequate lymph pumping function and may provide key information for the most efficacious treatment of rare lymphatic disorders in children.

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