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Familial Adenomatous Polyposis

FAP

Familial adenomatous polyposis (FAP) is characterized by the early onset of hundreds to thousands of adenomas in the rectum and colon.


Presentation

Symptoms are uncommon until the adenomas are large and numerous causing hematochezia or anemia. Other non-specific complaints such as change in bowel habits, constipation, diarrhea and abdominal pain may occur.

75 to 80% of affected individuals have a family history of polyps or colorectal cancer at age 40 years or younger. Patients can also develop a variety of extracolonic manifestations.

Pain
  • A 38-year-old lady presented with abdominal pain, diarrhoea and iron deficiency anemia. There was no history of colorectal cancer in the family.[ncbi.nlm.nih.gov]
  • We ask about general symptoms (anxious mood, depressed mood, fatigue, pain, and stress) regardless of condition. Last updated: May 14, 2019[patientslikeme.com]
  • […] to manage the pain and inflammation. are well documented to reduce adenoma numbers in FAP, and all CRCs in FAP arise from adenomas.[wiki.cancer.org.au]
  • These operations can often be done laparoscopically, making the procedure less painful and less debilitating. Video Endoscopic Sequence 10 of 12.[gastrointestinalatlas.com]
Weight Loss
  • The patient is currently in good health without recurrence, weight loss, or severe diarrhea at 12 months after surgery.[ncbi.nlm.nih.gov]
  • In the event of malignancy, an individual may experience weight loss, persistent unexplained fatigue, altered bowel movement and, if the tumours are not treated in time, cancer metastasis to areas such as the liver.[genomicseducation.hee.nhs.uk]
  • Nonspecific symptoms may include constipation or diarrhea, abdominal pain, palpable abdominal masses and weight loss.[orpha.net]
Virilization
  • Here we describe a 47-year-old female FAP patient with clinical manifestations of virilization who was found to have an ovarian steroid cell tumor, a rare neoplasm not known to be associated with FAP.[ncbi.nlm.nih.gov]
Wound Infection
  • Significant postoperative complications included wound infection in 1 patient, pancreatic fistula [International Study Group on Pancreatic Fistula definition (ISGPF) grade B] in 4 patients.[ncbi.nlm.nih.gov]
Leg Edema
  • A 29-year-old female visited a hospital because of increasingly severe lower leg edema. She was diagnosed as having multiple polyps in the stomach and colon by gastroscopy and sigmoidoscopy as well as multiple liver tumors by abdominal CT.[ncbi.nlm.nih.gov]
Abdominal Pain
  • A 38-year-old lady presented with abdominal pain, diarrhoea and iron deficiency anemia. There was no history of colorectal cancer in the family.[ncbi.nlm.nih.gov]
  • Other non-specific complaints such as change in bowel habits, constipation, diarrhea and abdominal pain may occur. 75 to 80% of affected individuals have a family history of polyps or colorectal cancer at age 40 years or younger.[symptoma.com]
  • pain, anemia, and/or mucosal discharge 4.[radiopaedia.org]
  • Abnormal signs and symptoms that may develop in the course of the disease include: rectal bleeding abdominal pain diarrhea anemia If your child has FAP, they may have other abnormal growths or lesions in other areas of the body, such as the thyroid, eyes[childrenshospital.org]
  • Nonspecific symptoms may include constipation or diarrhea, abdominal pain, palpable abdominal masses and weight loss.[orpha.net]
Blood in Stool
  • It is important to note that presence of blood in stool does not mean that the individual has colon cancer because blood may also be present in stool as a result of many non-cancer conditions Hence, a colonoscopy with a tissue biopsy is required to make[dovemed.com]
Meningism
  • Abstract A 15-year-old girl with adenomatous polyposis coli gene (APC) mutation and brain tumor-polyposis syndrome developed an unusual succession of cervicocephalic tumors (medulloblastoma, meningeal low-grade myxoid tumor, and papillary thyroid carcinoma[ncbi.nlm.nih.gov]

Workup

Diagnosis is based on family history, clinical findings and large bowel endoscopy or full colonoscopy. Barium enema and virtual colonoscopy can also be used to suggest the diagnosis of FAP. The clinical diagnosis should be confirmed by genetic testing. Familial Adenomatous Polyposis is diagnosed in a patient with one of the following:

  • One hundred or more colorectal adenomatous polyps
  • Fewer than 100 adenomatous polyps and a relative with FAP or 10 to 100 adenomatous polyps and a first degree relative with FAP
  • Detection of a germline mutation in the APC gene

Periodic ultrasounds or computed tomography scans are used to check for intra-abdominal desmoid tumors and thyroid or pancreatic cancer.

Polyps
  • Familial Adenomatous Polyposis is diagnosed in a patient with one of the following: One hundred or more colorectal adenomatous polyps Fewer than 100 adenomatous polyps and a relative with FAP or 10 to 100 adenomatous polyps and a first degree relative[symptoma.com]
  • They both presented with gastrointestinal bleeding and numerous rectal and colonic polyps were identified at colonoscopy. Histological examination of the polyps in both cases revealed features in keeping with adenomatous polyps.[ncbi.nlm.nih.gov]
  • People with the autosomal recessive type of this disorder have fewer polyps than those with the classic type. Fewer than 100 polyps typically develop, rather than hundreds or thousands.[ghr.nlm.nih.gov]

Treatment

Treatment for the disorder depends on the genotype. Monitoring is mainly based on endoscopic surveillance to detect the onset of polyposis. Prophylactic colectomy in FAP is usually performed shortly after polyps are discovered.

Several surgical options exist: total abdominal colectomy with ileorectal anastomosis, total proctocolectomy with ileal pouch anal anastomosis, total proctocolectomy with end ileostomy and total proctocolectomy with continent ileostomy [7] [8] [9].

Prognosis

FAP patients have a higher likelihood of dying than their age-matched healthy counterparts. Causes of FAP-related morbidity include perioperative complications, duodenal/periampullary malignancy, and desmoids.

Etiology

Familial adenomatous polyposis is caused by different inheritance patterns and different genetic mutations. Mutations in the APC tumor suppressor gene cause classic familial adenomatous polyposis and attenuated familial adenomatous polyposis. Mutations in the MUTYH gene are associated with autosomal recessive familial adenomatous polyposis [3].

Epidemiology

The reported incidence of familial adenomatous polyposis varies from 1 in 7,000 to 1 in 22,000 individuals worldwide. The mean age for the development of colon cancer in the untreated individual is 39 years. Males and females are equally affected [2].

Colorectal cancer and diffuse mesenteric fibromatosis are the two main causes of mortality. Diffuse mesenteric fibromatosis is reported in 4 to 32% of patients.

Sex distribution
Age distribution

Pathophysiology

Mutations in the APC gene cause both classic and attenuated familial adenomatous polyposis. APC is a tumor suppressor protein that plays a central role in Wnt-1 signaling, in part by regulating the degradation of β-catenin, a protein that stimulates cell growth.

More than 300 different types of mutations are recognized today as the cause of FAP. Most of these mutations result in a truncated and nonfunctional protein. The most common mutation, occurring in about 10% of FAP patients, is a deletion mutation in codon 1309. The number of polyps and the time frame in which they become malignant depend on the location of the mutation in the gene. APC mutations have also been linked to other certain cancers such as pancreatic or gastric adenocarcinomas or thyroid cancer [4] [5] [6].

Autosomal recessive FAP is characterized by a slightly increased risk of developing colorectal cancer and adenomas in both the upper and lower gastrointestinal tract and is caused by the inheritance of mutations in the base-excision-repair gene MUTYH. The phenotype of Autosomal recessive FAP is often indistinguishable from the other forms.

Prevention

There are no guidelines for prevention of FAP.

Summary

Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form in the epithelium of the colon. These polyps transform into colon cancer if left untreated.

There are three variants known existed. First, the classic familial adenomatous polyposis itself. Second, “attenuated FAP” (originally called “hereditary flat adenoma syndrome”). These two conditions are caused by APC gene defects, a tumor suppressor gene that is located on band 5q21. Third, the “autosomal recessive FAP” (or “MYH-associated polyposis (MAP)”) which is caused by MUTYH gene defects. The classic familial adenomatous polyposis is the most common and most severe form [1].

The presence of extracolonic manifestations is variable and may include gastric and duodenal polyps, dental abnormalities, congenital hypertrophy of the retinal pigment epithelium (CHRPE), osteomas, benign cutaneous lesions, diffuse mesenteric fibromatosis, hepatoblastoma, and extracolonic cancers.

Patient Information

Familial adenomatous polyposis is a rare genetic condition that causes polyps to form in the intestines. If untreated, these polyps almost always turn into cancer, usually by age 40.

FAP affects approximately 1 in 10,000 people, men and women equally. The majority of cases are due to a mutation in the adenomatous polyposis coli (APC) gene. Most people with familial adenomatous polyposis need surgery to remove the colon with all its polyps to prevent cancer.

References

Article

  1. Wertz DC, Fanos JH, Reilly PR. Genetic testing for children and adolescents: who decides?. JAMA 1994;272:875-881
  2. Alm T. Surgical treatment of hereditary adenomatosis of the colon and rectum in Sweden during the last 20 years. Part II. Patients with prophylactic operations, primary and late results. Discussion and summary. Acta Chir Scand 1975, 141:228-237.
  3. Groden J, Thliveris A, Samowitz W, et al. Identification and characterization of the familial adenomatous polyposis coli gene. Cell 1991;66:589-600
  4. Carter MA. Patient-provider relationship in the context of genetic testing for hereditary cancers. In: Hereditary breast, ovarian, and colon cancer. Journal of the National Cancer Institute monographs. No. 17. Washington, D.C.: Government Printing Office, 1995:119-21.
  5. Nishisho I, Nakamura Y, Miyoshi Y, et al. Mutations of chromosome 5q21 genes in FAP and colorectal cancer patients. Science 1991;253:665-669
  6. Kinzler KW, Nilbert MC, Su L-K, et al. Identification of FAP locus genes from chromosome 5q21. Science 1991;253:661-665
  7. Ziv Y, Church JM, Oakley JR, McGannon E, Schroeder TK, Fazio VF. Results after restorative proctocolectomy and ileal pouch anal anastomosis in patients with familial adenomatous polyposis and coexisting colorectal cancer. Br J Surg 1996, 83:1578-1580.
  8. Setti-Carraro P, Nicholls RJ. Choice of prophylactic surgery for the large bowel component of familial adenomatous polyposis (Review). Br J Surg 1996, 83:885-892.
  9. Kartheuser A, Parc R, Penna C, Tiret E, Frileux P, Hannoun L, Nordlinger B, Loygue J. Ileal pouch-anal anastomosis as the first choice operation in patients with familial adenomatous polyposis. A ten years experience. Surgery 1996, 119:615-23.

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Last updated: 2019-07-11 20:11