Lymphoscintigraphy for the Differential Diagnosis of Peripheral Edema and Intracavitary Lymph Effusion

Lymphedema of lower extremities is classified according to the International Society of Lymphology staging system; alternatively, the clinical, etiologic, anatomic, and pathophysiologic classification for venous edema can be used, adapted to lymphedema (CEAP-L). Objective measurement of limb edema can be problematic and different methods can be employed (circumferential measurements, immersion techniques). Bioimpedance spectroscopy and high-resolution cutaneous ultrasonography can be used to evaluate fluid accumulation, as well as the increased dermal thickness and skin echogenicity changes associated with edema. Differential diagnosis starts with the exclusion of other causes of lower extremity swelling. Venous Doppler ultrasound should be performed to exclude deep venous thrombosis or venous disease, which can be associated with lymphedema. Lymphatic impairment is demonstrated by lymphoscintigraphy, which is considered the method of choice to evaluate lymphatic pathways and their drainage pattern. In fact, contrast lymphangiography is no longer routinely performed because it can lead to severe complications, and magnetic resonance lymphangiography with the interstitial injection of an extracellular paramagnetic contrast agent is still an experimental procedure. The main clinical applications of lymphoscintigraphy and clinical results are described in this chapter.