A SQUAMOUS CELL CARCINOMA or ADENOCARCINOMA the which originates from the squamous EPITHELIUM of the ANAL CANAL , but may also arise from the transitional zone between the columnar epithelium of the rectum and the squamous epithelium of the anal canal (cloacogenic or transitional carcinoma) and is often associated with human papillomavirus infection. May be associated with a rearrangement in chromosome 3 and in the long arm of chromosome 11. OMIM: 105580
