Increased lymphoscintigraphic flow pattern in the lower extremity under evaluation for lymphedema

To analyze the clinical and scintigraphic features in four postoperative patients with lower limb edema.

Four case reports are presented, and causes of increased lymphatic flow are discussed.

Filtered 99mTc-sulfur colloid (0.1 mL; 20 MBq) was administered by subcutaneous injection into the second web space of each foot. Sequential local (inguinal) and whole-body imaging was performed periodically up to 24 hours after the injections. The patients were three women who were 40, 51, and 86 years of age and an 81-year-old man.

Each patient had unilateral lower extremity swelling and had recently undergone an ipsilateral lower limb operation. One female patient had previously undergone proximal femoral vein ligation, and another female patient had venous insufficiency demonstrated by Doppler ultrasonography. The male patient had a history of severe arterial insufficiency, and the remaining female patient had no venous or arterial abnormalities. On lymphoscintigraphy, all patients showed increased lymphatic flow in the edematous lower limb. Only the male patient also demonstrated abnormal dermal backflow pattern.

Increased lymphatic flow most likely is a normal response to lower limb edema in the presence of normal peripheral lymphatic structures. In the four described cases, a recent lower limb surgical procedure may have resulted in disturbance of normal proximal lymphatic channels. The role of sympathetic innervation of the peripheral lymphatic system is a potential factor determining lymphatic response to trauma or surgical intervention. Increased flow on lymphoscintigraphy may not necessarily represent normal flow, especially if other scintigraphic features of abnormal lymphatic function-such as dermal backflow pattern-are present.