What Causes Running Nose Along With Blisters Around The Nose Of A Child?

Tommy is a 5-year-old white boy who is brought to a family practice office with a “runny” nose that started about 1 week ago but has not resolved. He has been blowing his nose quite frequently and “sores” have developed around his nose. His mother states, “The sores started as ‘big blisters’ that rupture; sometimes, a scab forms with a crust that looks like “dried maple syrup” but continues to seep and drain.” She is worried because the lesions are now also on his forearm. Tommy’s past medical and family histories are normal. He has been febrile but is otherwise asymptomatic. The physical examination was unremarkable except for moderate, purulent rhinorrhea and 0.5- to 1-cm diameter weeping lesions around the nose and mouth and on the radial surface of the right forearm. There is no regional lymphadenopathy. What is the likely name and cause of these lesions? Why have these lesions spread to Tommy’s arm?