Chronic Unilateral Leg Swelling After Negative Venous Investigations: Recognizing Secondary Lymphedema in a Patient with Prior Pelvic Surgery.

Unilateral lower limb swelling is a common clinical presentation, and deep vein thrombosis (DVT) remains the most important diagnosis to exclude. Several conditions, however, may clinically mimic DVT and pose a diagnostic challenge. We report the case of a 69-year-old woman who presented with progressive unilateral left lower limb swelling. Despite high clinical suspicion and a Wells score of 5, DVT was excluded by a negative D-dimer result and repeated venous ultrasonography. Computed tomography imaging demonstrated no pelvic obstruction or malignancy. As the swelling persisted despite conservative measures, the diagnostic focus shifted. Three months later, a positive Stemmer's sign prompted indocyanine green lymphography, which demonstrated impaired lymphatic drainage, establishing the diagnosis of secondary lymphedema. She underwent complete decongestive therapy (CDT) followed by lymphovenous anastomoses (LVA) and remains on follow-up with CDT. A history of prior hysterectomy may have represented a predisposing factor for underlying lymphatic vulnerability. This case highlights the importance of considering alternative diagnoses when evaluation for DVT is negative and recognizing the potential role of pre-existing lymphatic impairment in atypical clinical progression.