Familial adenomatous polyposis syndrome
Familial polyposis coli, attenuated familial adenomatous polyposis and Gardner syndrome are all variants of the same disease and FAPS is used to described the entire spectrum.
FAPS affects 1 in 10,000 births 1,3. The average age of presentation is 16 years.
Typical symptoms and signs include rectal bleeding, diarrhoea, abdominal pain, anaemia, and/or mucosal discharge 4. Polyps usually develop around puberty 5.
FAP is characterised by the presence of hundreds or thousands of colonic adenomatous polyps, usually tubular or tubulovillous. The rectum is occasionally spared. Less commonly they affect the small bowel and stomach.
FAPS results from mutation of the tumour supressor adenomatous polyposis coli (APC) gene located on chromosome 5q21-2. Around one-third of cases are thought to be sporadic (i.e. no family history) and two-thirds thought to be familial 1.
MUTYH gene has been associated with APC-negative FAPS; this has an autosomal recessive inheritance 6 and this is often called MUTYH-associated polyposis (MAP).
- colorectal carcinoma (see below)
- hepatoblastoma (400x increased risk compared to general population 3)
- extracolonic polyps (stomach, duodenum)
- desmoid tumours
- dental anomalies
- congenital hypertrophy of the retinal pigment epithelium
There are three variants of FAPS:
- Gardner syndrome
- attenuated familial adenomatous polyposis
- familial polyposis coli
FAPS has a varied imaging appearance and demonstrate innumberable polyps. Imaging usually underestimates the number of polyps because most are <5mm in size. Features of colorectal carcinoma (CRC) should also be actively sought out.
Treatment and prognosis
FAPS accounts for 0.5% of CRC cases with ~7% of FAP carriers developing CRC by age 21 with almost every carrier developing CRC by 35-40 years 1,2.
Total colectomy with ileoanal anastomosis is generally considered the surgical treatment of choice 5.
Other polyposis syndromes should be considered 6:
- 1. Zua, Mene Sugage. "Familial adenomatous polyposis syndrome." Hospital Physician 35 (1999): 61-68.
- 2. Galiatsatos P, Foulkes WD. Familial adenomatous polyposis. Am. J. Gastroenterol. 2006;101 (2): 385-98. doi:10.1111/j.1572-0241.2006.00375.x - Pubmed citation
- 3. Monsalve J, Kapur J, Malkin D et-al. Imaging of cancer predisposition syndromes in children. Radiographics. 2011;31 (1): 263-80. doi:10.1148/rg.311105099 - Pubmed citation
- 4. Abdominal Imaging. Springer. ISBN:3642133266. Read it at Google Books - Find it at Amazon
- 5. Gore RM, Levine MS. Textbook of Gastrointestinal Radiology. Saunders. (2008) ISBN:1416023321. Read it at Google Books - Find it at Amazon
- 6. Gore RM, Levine MS. High Yield Imaging: Gastrointestinal: Expert Consult - Online and Print, 1e (HIGH YIELD in Radiology). Saunders. ISBN:1416055444. Read it at Google Books - Find it at Amazon
- 7. Ellis CN. Colonic adenomatous polyposis syndromes: clinical management. Clin Colon Rectal Surg. 2008;21 (04): 256-62. doi:10.1055/s-0028-1089940 - Free text at pubmed - Pubmed citation