An observation made during a routine eye exam can be the first indication of a serious, underlying genetic disorder. A specific finding on the retina, the light-sensitive tissue at the back of the eye, is strongly linked to Gardner’s syndrome, a condition that significantly increases the risk for certain cancers. This connection highlights how a non-invasive examination can initiate early detection. Understanding this link is important for identifying individuals at risk long before more serious symptoms develop.
What is Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE)?
The retinal pigment epithelium, or RPE, is a single layer of pigmented cells located at the back of the eye, just behind the retina. This cell layer has several functions, including absorbing stray light and transporting nutrients to retinal cells. Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) describes a benign and stationary lesion on this layer, similar to a freckle that is present from birth.
These lesions are most often discovered by chance during a routine dilated eye exam, as they are asymptomatic and do not affect vision. A common presentation of CHRPE is a solitary, well-defined, dark spot in one eye. Another harmless variation is called grouped CHRPE, where multiple lesions are clustered together in one section of the retina, often referred to as “bear tracks.”
An Overview of Gardner’s Syndrome
Gardner’s syndrome is a rare, inherited disorder caused by a mutation in the adenomatous polyposis coli (APC) gene. This gene is a tumor suppressor, meaning its function is to regulate cell growth and prevent cells from multiplying too rapidly. When a mutation occurs in the APC gene, this control is lost, leading to the formation of abnormal growths.
The most significant clinical feature is the development of hundreds to thousands of polyps in the colon and rectum, which typically begin to appear during the teenage years. If left untreated, there is a nearly 100% chance that these polyps will progress to colorectal cancer.
Beyond the gastrointestinal tract, Gardner’s syndrome is characterized by a range of other growths. These extracolonic manifestations include:
- Noncancerous bone tumors called osteomas, which commonly form on the jaw and skull.
- Numerous skin abnormalities, such as epidermoid cysts and fibromas.
- Aggressive, though non-cancerous, fibrous tumors known as desmoid tumors, often within the abdomen.
Connecting the Eye Finding to the Systemic Condition
The link between the eye and Gardner’s syndrome is established through a specific presentation of CHRPE that differs from the common, benign forms. While a single CHRPE lesion or a cluster of “bear tracks” in one eye is harmless, a distinct pattern known as atypical CHRPE is a strong clinical marker for the syndrome. These atypical lesions are the earliest and most common sign of the condition, present in up to 90% of patients with Gardner’s.
These atypical CHRPEs have several defining characteristics. They are found in both eyes (bilateral) and are scattered across the retina. The presence of four or more of these lesions is a significant indicator. Their shape is distinctively irregular and often described as “pisciform,” resembling a fishtail, with a depigmented border.
Because these specific eye findings are congenital, they can be detected by an ophthalmologist years before intestinal polyps or other symptoms of Gardner’s syndrome emerge. Their discovery during an eye exam provides an early opportunity to identify individuals who have inherited the mutated APC gene.
The Diagnostic and Screening Pathway
The process of diagnosing Gardner’s syndrome often begins when an ophthalmologist identifies the characteristic bilateral, multiple, and irregularly shaped CHRPE lesions. This finding prompts a referral for further medical evaluation, typically to a gastroenterologist, and may also include a recommendation for genetic counseling. The counselor can discuss the inheritance patterns of the disorder, as it is an autosomal dominant condition, meaning a child of an affected parent has a 50% chance of inheriting it.
Genetic testing is the definitive method to confirm the diagnosis. A blood test is performed to look for a mutation in the APC gene. Regardless of the genetic test results, the next step is a direct visual examination of the colon. A colonoscopy is performed to check for the presence of adenomatous polyps, and for individuals at risk, this screening often begins in early adolescence.
Long-Term Management and Monitoring
Once a diagnosis of Gardner’s syndrome is confirmed, a lifelong plan of surveillance and management is initiated to mitigate the high risk of cancer. The primary focus of this management is the gastrointestinal system. Patients require regular colonoscopies, often annually, to monitor and remove polyps before they can become malignant.
Due to the extremely high likelihood of developing colorectal cancer, the standard treatment recommendation is often a prophylactic colectomy, which is the surgical removal of the colon. This surgery is advised when the number of polyps becomes too large to manage through individual removal, usually around late adolescence or early adulthood.
Management extends beyond the colon to address the other manifestations of the syndrome. Patients undergo periodic screenings for desmoid tumors, osteomas, and other related growths. Dental examinations are also part of the monitoring process. The CHRPE lesions in the eyes do not require any treatment themselves, but routine eye exams remain a component of the patient’s overall health monitoring.