Anal cancer is a malignant tumor inside the anal canal, i.e the transition of the rectum into the anus. It often develops after chronic pre-damage of the anal region through fistulas, fissures (painful cracks) or wart-like growths (warts) e.g. as a result of sexually transmitted diseases.For the histological picture I'm indebted to Dr. H. Riemenschneider, a pathologist from Würzburg.
