is a pore whose distended openings is partially blocked, allowing some of the keratin, sebum (oil) and bacteria to drain to the surface. Blackheads tend to have a constant structure, and it may take a pretty long time to clear.
is a closed pore filled with trapping sebum, bacteria, dead skin cells, causing a white look on the surface. These acne lesions sometimes seem to be easy popped. Make sure you know how to do that
in a proper way before you try.
is a solid lesion shaped like capsules and contains liquid or semi-liquid pus similar to that found in pustules. Theese are the most painful lesions caused by acne and can sometimes last for months. Nodules and cysts tend to extend into the deeper layers of the skin and are known to lead to tissue destruction. Don't try to pop such a lesion, otherwise you may cause severe trauma and the lesion may last for much longer time than it normally would. Nodular acne and cysts is a severe form of acne that is treated only with isotretinonin.