Paroxysmal hemoglobinuria prompted by exposure to cold; marked by shaking chills, back and leg pain, headache, abdominal cramps and fever, jaundice, transient splenomegaly, paresthesias, urticaria; and cyanosis. Condition is associated with syphilis infection, but most cases are idiopathic. Wide range in temperature drop is needed to initiate attacks. Treatment is avoidance of cold exposure and steroids; course is usu. benign.