The chickenpox rash may have several stages that develop quite rapidly. It starts in the area of the head and spread towards the trunk and limbs (though it involves the trunk more than the limbs). The rash comprises of flat, red lesions (macules) that evolve into raised lesions (papules). These then turn into blisters filled with clear fluid (vesicles), which then turn into pus-filled blisters (pustules). The lesions then finally form a crusted coat, dry up, fall off and heal.
One of the most important characteristics of chickenpox is the presence of lesions at all stages of development in an affected child. That means, we may be able to see papules, blisters, pustules and scabs all at the same time in the same affected location. This only happens with chickenpox.