However, it may turn out that it’s only a cyst…which is a lot less worrying. … A cyst can contain pus if infected but is quite different from something like an abscess or a boil. Sebaceous cysts are fairly common and are caused by problems with sebum-producing glands around the hair follicles covering our bodies.
If it becomes swollen or tender, home treatments may help. Putting a warm moist compress over the cyst may help it drain, for instance. Resist any temptation to pop or squeeze the cyst, like a pimple. But if it’s inflamed and causing discomfort, you should see a doctor.
The whitish-yellow, yellow, yellow-brown, and greenish color of pus is the result of an accumulation of dead neutrophils. Pus can sometimes be green because some white blood cells produce a green antibacterial protein called myeloperoxidase. … Pus from infections caused by P. aeruginosa is particularly foul-smelling.