A patient presents with acute bright red discoloration and edema of the anterior calf skin. What is the most likely diagnosis?

The presence of acute bright red discoloration and edema of the anterior calf skin suggests a localized infection, which is a characteristic feature of cellulitis. Cellulitis typically arises from bacterial infections, often following skin injuries or existing skin conditions. In this case, the symptoms of acute onset, redness, and swelling are consistent with the inflammatory response associated with cellulitis.

Other conditions listed, while related to vascular and skin issues, present with different clinical signs. Deep vein thrombosis usually presents with unilateral swelling rather than redness and is often associated with pain rather than the overt signs of infection. Venous ulceration generally appears in chronic conditions with specific areas of skin breakdown, often accompanied by pigmentation changes and not acute redness. Lymphedema typically causes gradual swelling without the bright red discoloration and is usually chronic, not acute.

Given the acute symptoms described, the most fitting diagnosis is cellulitis, due to its specific clinical presentation of infection and inflammation in the skin.