Anal Fissure, Pruritus Ani, Papillitis, and Cryptitis

Anal Fissure

Anal fissure is a tear of the skin in the distal anal canal, usually in the posterior midline ( Fig. 104.1 ). Occasionally, it is in the anterior midline. When not in the midline, anal fissure is often associated with an abnormality such as Crohn disease, human immunodeficiency virus (HIV) infection, tuberculosis, syphilis, or anal malignancy. Fissures usually are acute but may become chronic. The cause of an anal fissure typically is unknown, but it is clearly associated with increased resting anal pressure. Identifying this physiology has led to some of the most recent treatments. The exact incidence is not known, but anal fissure is relatively common.