Cutaneous Anthrax: What is the Hallmark?

A 71-year-old man complained of a blackish wound under his left eye, which began with fever and reddish spots after helping to slaughter a cow and cut its meat. The fever occured especially in the afternoon to evening, and is not accompanied by chills and sweating. On day 4 of fever onset, the fever diminished and the spots progressively widened with swelling.