Unilateral leg swelling with pitting edema, where pressure on the swollen area leaves an indentation, is often caused by issues with venous or lymphatic drainage in the affected leg. Common culprits include deep vein thrombosis (DVT), chronic venous insufficiency, and lymphedema, which can be primary or secondary to other conditions. Other potential causes include infections like cellulitis, or conditions like chronic regional pain syndrome (CRPS). 1. Venous Issues: Deep Vein Thrombosis (DVT): A