Red, raised bumps, accompanied by skin darkening is what ingrown hair cysts look like. These can be infected, and pus-filled, ...

Pilonidal sinus is a skin infection that causes a cyst near the buttocks, just beneath the tailbone. The infection often occurs when an ingrown hair grows internally and infects the skin.

The wound, caused by an ingrown hair ... works its way in under the skin. However, there is no enzyme to break down the hair and it becomes the focus of infection. Pilonidal cysts affect 26 ...