Why does a swollen leg sometimes feel warm?

Increased blood flow: Swollen leg can feel warm when cellulitis (infection of the soft tissues) is the cause. The inflammatory response to persistent swelling known as lipodermatosclerosis in venous disease is often painful and warm. Common denominator is vasodilation, relaxing of the vessel wall, resulting in increased blood flow, and hence the warmth.

Swollen leg: This is due to increase volume in the leg either blood or lymph fluid