Pilonidal Sinus

The pilonidal sinus is a small opening or tunnel in the skin. It can fill with fluid or pus and lead to a cyst or abscess. It occurs in the cleft at the top of the buttocks. A pilonidal cyst usually contains hair, dirt, and debris. This can cause severe pain and can often become infected. If it becomes infected, it may secrete pus and blood and have a foul odor. PNS is a condition that primarily affects men and is also common in young adults. It is also more common in people who sit frequently, such as taxi drivers.