Lymphoscintigraphy for differential diagnosis of peripheral edema: diagnostic yield of different scintigraphic patterns.

UNLABELLED Edema of the limbs is a common reason for medical consultation, for which the lymphoscintigraphy is considered to be a reliable method for its differential diagnosis. OBJECTIVE To evaluate the usefulness of radionuclide studies in the differential diagnosis of edema, and the diagnostic yield of different scintigraphic patterns. MATERIAL AND METHODS A total of 61 patients, mean age 43 years, referred to our Department in the last three years for suspected lymphoedema, were considered. One patient was discarded due to lack of diagnosis, 56 had lower limb edema and 4 upper limb edema. After intradermal injection of two doses of (99m)Tc-nanocolloid, scintigraphic scans were made at 30 and 120minutes. The final diagnosis was based on imaging tests, clinical course, and response to treatment. We calculated the parameters of the diagnostic yield of four different scintigraphic patterns (presence of dermal backflow, asymmetry-alteration in inguinal/axillary nodes, presence of collateral pathways, and visualization of intermediate lymph nodes), considering them individually and jointly. RESULTS The best diagnostic yield was achieved by considering dermal backflow and asymmetry in inguinal/axillary nodes (accuracy 88.9%, specificity 96.4%, PPV 95.5%). Evaluation of intermediate lymph nodes and presence of collateral pathways contributed little to the diagnostic yield, showing poor sensitivity and high false positive rates. CONCLUSION The lymphoscintigraphy had high diagnostic yield, allowing early treatment of lymphœdema. The dermal backflow and asymmetry in inguinal/axillary nodes had the greatest diagnostic accuracy. Evaluation of intermediate lymph nodes and visualization of collateral pathways contributed little to improving the diagnosis.