All you need to know about a Pilonidal Sinus
PILONIDAL SINUS - TAILBONE CYST
Pilonidal Sinus – the Latin term (Latin pilus ‚hair‘ und nidus ‚nest‘) is the most appropriate description of the disease. We are talking about inflammation of soft tissue in the area of the fold between the buttocks over the tailbone caused by ingrowing or intruding hair. It has nothing to do with the tailbone itself (“tailgut cyst”) or an embryonal malformation (“dermoid cyst”, “sacral dermoid”).
Development of a Pilonidal Sinus as a foreign body granuloma
A Pilonidal Sinus develops with the initiation of puberty when hair growth increases in number and thickness. A hair shaft may break by shear forces caused by sitting, the fragments get pushed back into the hair follicle. The follicle fills with keratin particles and gets distended so that the opening becomes visible as a tiny hole or black dot, called a “pit”. The body lacks enzymes to degrade hair particles and encloses them in a sheath of scar tissue, the fistula capsule. Bacteria can invade the cavity and cause inflammation. As long as the cavity can drain through the pit, a chronic inflammatory process leads to the development of a tubular duct, called fistula (Latin fistula ‚whistle, pipe‘). If fluid collects within the cavity, an encapsulated collection of pus can originate, the pilonidal abscess.