Published online Jun 21, 2017. doi: 10.3748/wjg.v23.i23.4135
Peer-review started: February 6, 2017
First decision: March 16, 2017
Revised: April 3, 2017
Accepted: May 9, 2017
Article in press: May 9, 2017
Published online: June 21, 2017
Processing time: 143 Days and 14.1 Hours
Attenuated adenomatous polyposis (AAP) is a poorly understood syndrome, that can be defined as the presence of 10-99 synchronous adenomas in the large bowel, and it is considered a phenotypic variant of familial adenomatous polyposis (FAP). This definition has the advantage of simplicity, but it may include sporadic multiple adenomas of the large bowel at an extreme, or FAP cases on the other side. AAP shows a milder phenotype than FAP, with an older age of onset of adenomas and cancer, and less frequent extracolonic manifestations. AAP may be diagnosed as a single case in a family or, less frequently, it may be present in other family members, and it shows distinct pattern of inheritance. In less than 50% of cases, it may be caused by adenomatous polyposis coli (APC) or MUTYH mutations, referred to as APC-associated polyposis, inherited as an autosomal dominant trait, or MUTYH-associated polyposis, which shows an autosomal recessive mechanism of inheritance, respectively. Surveillance should rely on colonoscopy at regular intervals, with removal of adenomas and careful histological examination. When removal of polyps is not possible or advanced lesions are observed, the surgical approach is mandatory, being subtotal colectomy with ileo-rectal anastomosis the treatment of choice. Studies on this syndrome are lacking, and controversies are still present on many issues, thus, other clinical and genetic studies are requested.
Core tip: Attenuated adenomatous polyposis is a poorly understood syndrome, which may be defined as the presence of 10-99 synchronous adenomas in the large bowel, when at least 50% of the polyps removed are adenomatous. It is a variant of Familial Adenomatous Polyposis with a milder phenotype. In less than 50% of cases, it is caused by adenomatous polyposis coli (APC) or MUTYH mutations, and less frequently by other genes. Surveillance should rely on colonoscopy at regular intervals, with removal of adenomas and careful histological examination. If removal of all polyps is not possible or advanced lesions are observed, the surgical treatment is mandatory.