7. Pilonidal sinus (PNS):

The pilonidal sinus (PNS) is a sinus tract or tiny channel that may open to the skin's surface and come from the site of the infection. This is a common condition in young age and adolescents and in people who spend a lot of time sitting and working, like drivers.

Symptoms include Pain in standing and sitting positions, swelling, pus or bloody discharge, red swollen skin, and hair protruding from the infected area.

Diagnosis is by digital examination and visual inspection.