You may have what is known as a pilonidal cyst.
A pilonidal cyst (from Latin meaning 'hair nest') is a blanket term for any type of skin infection near the tailbone. The term "pilonidal cyst" can be misleading, as a majority of the time, this is actually an abscess. These are normally painful, occur somewhat more often in men than in women (though, this is debatable), and normally happen in early adulthood (to the 30's). Although usually found near the tailbone, this painful condition can be found rarely in several other places, including the navel and armpit. A traumatic event is not believed to cause a pilonidal cyst, such an event that has been known to inflame an existing cyst.
It is a combination of two Latin words, pilus, meaning hair and nidal, meaning nest. The condition is now referred to as pilonidal sinus disease.
[edit] DiagnosisDoctors are not sure what causes a pilonidal cyst. An old theory is that a small and harmless cyst has always been present at birth, and that for some reason, it has become irritated and formed a painful abscess. Another explanation is that it is an ingrown hair that has formed an abscess. It is very rare to find hair follicles inside the cyst however,it is very common for drained cysts to contain hair, though this is not thought to be the sole cause of the condition. Contrast this to dermoid cyst (a teratoma).
