What It Is
The least you need to know (Cliff Notes Version):
A Pilonidal (Abscess, Cyst, Sinus, Dimple) is an abscess in the natal cleft (more commonly referred to as your butt crack) that tends to become infected and cause intense pain and drainage. Sometimes a Pilonidal contains hair and sometimes they don’t.
A few basic facts:
FACT: The term “Pilonidal” technically means “nest of hairs”. This is not always true and there are people who have Pilonidal abscesses that have no hair in them (most frequently the case in females.) Many doctors will tell you that all Pilonidals are caused by hair, this has not been proven to be true and certainly doesn’t explain how so many develop with no hair present. A Pilonidal cyst is basically an abscess beneath the skin - a boil gone very, very bad. Pilonidal abscess are prone to excruciatingly painful infections and they can expand (tunnel) .
FACT: The term “Pilonidal Cyst” is actually incorrect. 99% of all Pilonidals are actually abscesses, not cysts. Use of the word “cyst” has caused a great deal of misinformation about treatments among doctors and patients alike. Pathologists and surgeons on rare occasions find the sac is lined with epidermis, made up of cells from skin, but only cells from the outer layer of skin. That outer layer, which we call epidermis, contains no follicles. Pathologists find epidermis lines the sac only in rare late cases where epidermis has crept into a long-standing abscess in an attempt to heal it. They never find a sac lined with intact skin and follicles, only an occasional sac lined with epidermis.
FACT: While the terms Pilonidal Cyst and Pilonidal Sinus are frequently used interchangeably, they are not technically the same thing. A Pilonidal is an abscess; a pocket of infection below the skin. A sinus is a cavity/passageway that links the abscess with your outer skin. Not everyone who has a Pilonidal abscess has a Pilonidal Sinus; the sinus (and there can be more than one) is a small dimple-like hole, usually below the actual abscess, which allows it to drain.
FACT: Pilonidal abscesses usually occur at the top of the “natal cleft” (aka your butt crack). Their usual position is slightly to the left side, with sinus openings traditionally right along the midline (middle) of the cleft. Many people have cysts lower in the cleft or on both sides, it depends on the individual.
FACT: The peak incidence of Pilonidal Disease is between 16 and 26 (however, older and younger happens regularly too). It affects males only slightly more than females. It is uncommon (but not unknown) in Asian and Black peoples. We have heard from people in their 50’s having their first Pilonidal episode and from parents with children as young as 12. Our experience is that girls see signs earlier at the start of puberty (12 - 14) than boys, who we hear about more in the 16 - 22 range.
FACT: Many babies are born with a “Sacral Dimple”, however, this is not the same as the Pilonidals discussed on this site. Some Sacral Dimples will become infected and turn into Pilonidal abscesses, but most are harmless blind tunnels (which should be checked anyway for possible connections with other problems.)
FACT: Pilonidals rarely go away on their own. Most require some form of surgical intervention, although there are cases of “disappearance” after a lancing or antibiotic treatment. Pilonidals can go dormant for years at a time, lulling their owner into a false sense of escape. Some people have flare-ups every month and some people only get one every few years.
FACT: Pilonidal abscesses are medically related to a group of diseases known as Follicular Occlusion - meaning blocked hair follicles. At one time it was believed that Pilonidals were all congenital, however, current medical philosophy is that very few of these abscesses are congenital and most are acquired.