Pustules  may be  superficial or deep.  Superficial pustules  are  categorized as either active or  less active . As with papules, less active lesions  are smaller, less indurated and remain for a shorter length of time than  the active lesions. Pustules  are seen less frequently than papules but, like papules, commonly resolve via a macular phase; however, an intermediate papular phase in either the development  or regression of a pustule is not uncommon .

  More often than  not, the  patient tends  to squeeze pustules,  which probably  aids  resolution. However, unmodified pustules last for five days  - a shorter time than papules - possibly because the pustules  contain many  polymorphonucleocytes  whose  lysosomal   enzymes may be more capable of resolving the inflammation than the lymphocytes which are more a feature of papules.

  Deep pustules are much less common and are more frequently seen  in  subjects  with  severe  acne. They usually arise from a pre-existing inflammatory papule or nodule and may  persist in the pustular phase  for seven days or more. Again,  this type of lesion often provokes  interference  by  the  patient but with  less successful outcome. Deep pustules are slightly tender. Resolution of a deep pustule usually passes through a papular phase and may take 2-6 weeks.