From a colonoscopy, we diagnosed the cat scratch phenomenon (CSP), named after the remarkable resemblance to scratches of a cat on bare skin. The rest of the colon showed no macroscopic abnormalities.
Random biopsies were taken to investigate microscopic colitis since the patient presented with chronic diarrhoea. Histology showed collagenous colitis. CSP is rare condition (< 0.5% of all colonoscopies).1 It is caused by barotrauma (insufflation of air/CO2 ) and observed in the right hemicolon. It is mainly seen in older female patients. Although histology is normal in most cases, CSP is associated with collagenous colitis in 14-25% of all patients.1,2 Collagen deposition in the submucosal layer decreases compliance of the wall. Intraluminal pressure of CO2 may lead to mucosal tears.
Other associations of CSP are made with diversion colitis and ischemic colitis. CSP is considered an innocent finding. In small series of cases, no complications have been noted, although one incidental finding of pneumoperitoneum has been reported elsewhere.3