"Stocking effect" in lymphoscintigraphy

Lymphoscintigraphy following subcutaneous injection of a radiolabeled macromolecule, such as Tc-99m-nanocolloid, is used to investigate limb swelling, usually to confirm lymphedema. A well-known abnormal finding is dermal backflow, which occurs a result of diversion of lymph into skin lymphatic vessels. We describe a case in which this important sign was partially obscured by a stocking. The case also illustrates, first, the frequent though poorly recognized occurrence of lymphatic dysfunction in the clinically normal contralateral limb of a patient with unilateral swelling, and second, the principle underlying treatment with compression hosiery. Stockings should be removed before injection and all subsequent imaging.