Diagnosis & Symptoms

Colorectal Symptoms

Many people with early FAP experience no symptoms at all—polyps are discovered through screening in at-risk family members or when symptoms finally develop. When symptoms do occur, they may include bright red blood in the stool or on toilet paper, changes in bowel habits (increased frequency, diarrhea, or constipation), and abdominal cramping or bloating. As polyps accumulate and chronic bleeding occurs, some individuals develop anemia symptoms including fatigue, weakness, or shortness of breath.

Other Health Manifestations

Beyond the colon, FAP can affect other parts of the digestive system and the entire body. FAP polyps are what are called adenoma polyps. Adenomas are precancerous polyps, meaning they automatically carry the risk of becoming cancerous. While biopsied adenomas may be determined to be benign, that is not the same as not being at risk of becoming cancerous, it simply means that polyp has not yet become cancerous, or malignant.

In FAP, adenomas can anywhere in the body. Specifically in the GI tract, in addition to the colon and rectum, adenomas may also develop in the esophagus, stomach (gastric polyps), duodenum (the first part of the small intestine), small intestine, through to the anus.

The stomach and duodenum are common areas for polyps requiring surveillance and to better understand the  related terms often included in pathology results, let’s breakdown their anatomy.

The stomach is divided into 4 parts – cardia, fundus, body, and plyorus. The cardia is the first part of the stomach and is connected to the esophagus. The fundus is bulbous and dome shaped and at the end of it is the body of the stomach, the central and largest part. Ending the stomach is the pylorus which connects to the duodenum, the first part of the small intestine.

In addition to adenomas in the stomach, fundic gland polyps located in the fundus are also common among FAP patients and can be increased by PPI (Proton Pump Inhibitors) medication use. These polyps are generally benign and do not typically become cancerous in the general population. It is common for fundic gland polyps to have dysplasia in FAP patients and there is a difference between fundic gland polyps  from PPI use and FAP associated fundic gland polyps. FAP associated fundic gland polyps tend to show more APC gene alterations where those caused by PPI use do not. It also been indicated that PPI use serves as a protective factor against in dysplasia in polyps for those with FAP and other conditions.

Stomach polyps may cause indigestion, stomach pain, nausea, or early feeling of fullness and require ongoing surveillance due to increased risk for cancer. Due to the fragile surface of a polyp, irritation can occur resulting in bleeding. The larger a polyp the more blood supply the polyp has and therefore, may bleed more than a smaller sized polyp.

The small intestine is divided into 3 parts – duodenum, jejunum, and ileum. The duodenum is the first part and is c-shaped, curving around the head of the pancreas and is divided into four parts – superior, descending, inferior, and ascending. Halfway along the second part of the duodenum is the ampulla, which serves as a junction of the biliary and pancreatic ducts and digestive tracts. The ampulla or ampulla of vater is a duct which connects to the duodenum. Other ducts connecting to the duodenum include the bile and pancreatic duct. The major duodenal papilla is where these ducts enter the duodenum and is controlled by the sphincter of Oddi, which surrounds the duodenum. The sphincter of Oddi is a valve that controls the flow of bile and pancreatic juice into the duodenum.

Soft Tissue Manifestations

In 10-25% of FAP patients, benign but aggressive tumors called desmoid tumors develop, typically in the abdomen. These can cause abdominal swelling, pain, or in severe cases, bowel obstruction symptoms. These desmoids require close monitoring and may need medical or surgical treatment.

Fibromas, lipomas, and epidermoid cysts are also associated with FAP. Fibromas and lipomas are both tumors that can grow anywhere in the body and are both generally benign. Fibromas are made up of fibrous or connective tissue while lipomas are made up of fatty tissue. Epidermoid cysts are slow growing bumps under the skin that may contain fluid, air, or other substances.

Dental and Bone Abnormalities

Dental and bone abnormalities associated with FAP include osteomas, impacted teeth, supernumerary teeth, hypodontia, and odontomas. Osteomas are benign, bone tumors that typically grow on the skull or jaw but may also develop in the sinuses, ribs, or long bones such as the legs. Supernumerary teeth and hypodontia are both congenital manifestations of FAP meaning that from birth the individual has extra permanent teeth or the absence of some permanent teeth, respectively. Odontomas are benign, dental tumors composed of dental tissue that grows in an irregular way.  

Associated Cancers

Additional cancers commonly associated with FAP include other GI cancers, Thyroid, Pancreas, Liver, Central Nervous System, Adrenal, and Bile Ducts. However, FAP polyps (adenomas) can develop anywhere in the body. 

Thyroid cancer occurs in approximately 2% of FAP patients, predominantly in women and particularly in those with Latinx heritage. Most thyroid nodules are discovered during screening exams without causing symptoms, though some individuals may notice throat discomfort or voice changes.

Children with FAP from ages 0-5 are at higher risk for hepatoblastoma (a type of liver cancer) requiring regular monitoring, typically every 3-6 months. 

Eye Manifestations

Occasionally, small “freckles” or “bear tracks” called congenital hypertrophy of the retinal pigment epithelium (CHRPE) may be visible during an eye exam—these are generally harmless and don’t affect vision but can be a helpful diagnostic sign. Although generally harmless, maintaining regular monitoring of identified CHRPEs can be beneficial as a preventative measure should any changes begin to occur.