PILONIDAL CYST, RUDIMENTARY REST OF THE TAIL, THE REASON OF SACROCOCCYGEAL PURULENCE

Chronic purulence in sacrococcygeal area, not related to rectum, is normally explained by either hair growth disorder in this area, its growth into the skin (pilonidal disease), or by purulence of tail remnant of spinal cord (theory of ectodermic invagination). There are no morphological confirmations for these theories, and etiology of the disease continues to be subject of discussion. During examination of 500 cadavers of childr en and adults in 23 cases in the skin in coccygeal area there is either already formed, non-purulent pilonidal sinus , or clearly expressed skin funnel or deep skin fold. The microscopy of skin sections in pilonidal sinus or in coccygeal skin funnels and folds in all cases we detected connective tissue band, connecting the skin fossa and sacral periosteum. This band may be viewed as caudal ligament ? lig.caudale, which was theoretically predicted but wasn’t seen before. Pilonidal sinus manifests in incomple te reduction of tail levator muscles leaving the ligament connecting skin fold to coccyx. With development of fatty tissue in this site there is often formed a narrow channel with hairs often infected due to proximity of rectum. This atavistic feature occu rs simultaneously with other atavism - spina bifida of sacral or coccygeal vertebrae.