What is Congenital Hypertrophy of Retinal Pigment Epithelium?
Congenital hypertrophy of the retinal pigmented epithelium (CHRPE) is a harmless eye condition marked by specific, pigmented spots mainly found in the back part of the eye known as the fundus. These spots, or CHRPE lesions, tend to occur alone in one eye, but there have been accounts of them appearing more than once or in both eyes. Most of the time, these spots are found during routine eye check-ups, usually in people who don’t have any symptoms.
By looking at the eye, doctors can identify if these spots are alone, grouped, multiple, or peculiar. The latter occurrence of the spots can mean a person has certain illnesses, like familial adenomatous polyposis (FAP) syndrome, Gardner syndrome, or Turcot syndrome.
Even though these spots are generally harmless, they sometimes can turn into cancer. So, patients who have CHRPE should have a full body check-up to see if they also have associated illnesses. If you have one of these spots, your doctor will monitor it during your regular eye check-ups to keep an eye out for any changes that might hint at cancer or growth. When these spots are connected to the FAP syndrome, a team of doctors, including gut health doctors for bowel cancer screening, and genetic counseling, is required.
Even though these spots usually do not need any treatment, it is crucial for the patient to understand the possible risk of them turning into cancer and the need for regular check-ups.
What Causes Congenital Hypertrophy of Retinal Pigment Epithelium?
CHRPE stands for “congenital hypertrophy of the retinal pigment epithelium,” and it describes various conditions that look similar but are actually quite different in cause, outcome, and treatment. Below are the different types of CHRPEs based on various studies:
Solo CHRPE: This type happens usually in one eye and is not related to any specific body system conditions. They tend to occur randomly, and they’re almost always harmless. Solo CHRPEs are often seen as the only “real” CHRPEs.
Grouped CHRPE: These types of lesions usually occur in one eye and look like solo CHRPE but multiple of them. They cluster together within one part of the retina, often referred to as “bear tracks.” They are present from birth, harmless, and not related to any body conditions.
Pigmented ocular fundus lesions of familial adenomatous polyposis (PO-FLs) or Multiple CHRPEs: These look like grouped CHRPEs but usually occur in both eyes. They’re different from other CHRPEs because they’re linked with a group of genetic colon polyps conditions. The location of the gene mutation (adenomatous polyposis coli, or APC) can affect whether these lesions appear.
Familial adenomatous polyposis (FAP) is a genetic condition that leads to the development of many polyps in the colon. If left untreated, it can lead to colorectal cancer in patients. This condition has an enormous number of colorectal adenomas, has rare types of FAP, and all other mutations lead to intermediate FAP. Some gene mutations are associated with CHRPE lesions, while others aren’t.
FAP can cause other symptoms outside of the colon, like CHRPE-like lesions in the retina. Some variants of FAP, like Gardner syndrome and Turcot syndrome, can also lead to the development of PO-FLs. Due to the serious potential outcomes of this condition, eye doctors must be able to tell the difference between PO-FLs and harmless forms of CHRPE.
Risk Factors and Frequency for Congenital Hypertrophy of Retinal Pigment Epithelium
The actual frequency of a condition known as typical CHRPE isn’t very clear because the numbers given in scientific papers vary widely, ranging from 0.4% to 30% of the population. In one study involving 1745 people, only 1.20% were found with this condition. Only 2 of these people had multiple CHRPE lesions, which makes the occurrence of multiple lesions less than 1%. All these multiple lesions were found on one side of the body. According to several studies, men and women are equally likely to have typical CHRPE lesions.
One research found that 78% of patients with a disease called FAP and 38% of their siblings had CHRPE. Up to 90% of patients with FAP could have multiple CHRPEs. FAP itself affects approximately 1 in every 8300 to 37,600 people, but on average, the condition occurs in 1 in 10,000 people. One review of the literature found that CHRPE is a good marker of FAP, being correct (specific) in about 89% of cases and detected (sensitivity) in about 79% of cases.
Signs and Symptoms of Congenital Hypertrophy of Retinal Pigment Epithelium
Solitary or Unifocal Congenital Hypertrophy of the Retinal Pigmented Epithelium (CHRPEs) are usually flat and dark colored, but can vary in appearance due to internal nodules and the level of pigmentation. The size and shape can also differ but they often have a ring around them. These CHRPEs are typically found in a specific part of the eye but can be located elsewhere in rare instances. They might affect vision if they involve some important eye structures. These CHRPEs are usually found in people between age 1 to 80 and are not associated with other diseases such as colon cancer.
- Usually flat and dark-colored
- Can vary in appearance due to internal nodules and pigmentation
- They are mostly found in a specific part of the eye
- They rarely affect vision
- Usually found in people between age 1 to 80
- Not associated with diseases like colon cancer
Grouped or Multifocal Congenital Hypertrophy of the Retinal Pigmented Epithelium and Grouped Pigmentation of the Retina occur in clusters and often look like animal footprints. They typically resemble solitary CHRPEs but are generally smaller and lack the typical surrounding halo and lacunae. They are also typically not associated with severe diseases.
- Occur in clusters
- Often look like animal footprints
- Generally smaller in size
- Lack the typical surrounding halo and lacunae
- Not usually associated with severe diseases
Pigmented Ocular Fundus Lesions of Familial Adenomatous Polyposis and Familial Adenomatous Polyposis–Associated Lesions differ from benign CHRPEs and are linked with a severe systemic disease. They often have irregular shapes and borders and differ in pigmentation, size, and distribution.
- Differ from benign CHRPEs
- Associated with severe systemic disease
- Irregular in shape and borders
- Vary in pigmentation, size, and distribution
Testing for Congenital Hypertrophy of Retinal Pigment Epithelium
To find CHRPE lesions, or certain spots on the retina, doctors usually perform a detailed eye exam after dilating the pupil. This can sometimes be done through non-eye-dilating imaging as these spots are rarely found in the back of the eye. Biomicroscopes with a special filter can help tell the difference between these lesions and other spots known as choroidal nevi.
An optical coherence tomography (OCT) test can show thickening and other changes in the retina due to elongated cells. The thickening causes shadows on the under layer of the eye, thinning the retina, and causing cell loss. Big lesions can potentially affect vision, reflected by loss of visual field.
Fluorescein angiography is a test that reveals darker spots due to blockage caused by thicker cells in front of the blood vessels of the eye. Any hollow spaces within these spots will appear brighter. Sometimes, changes in the blood vessels in the retina may also be noticed using this test.
Indocyanine green angiography, another exam, shows blocked areas within pigmented lesions, though the vessels in the back of the eye may still be visible.
Next, Fundus autofluorescence imaging typically manifests CHRPE spots as very dim, although hollow spaces might show slight brightness due to their composition. B-scan ultrasound isn’t typically diagnostic for CHRPE but can help in measuring the thickness of the lesion.
Visual field analysis may show a defect in the area of the CHRPE, but these defects are usually not detected because most lesions are located more peripherally than the testing area. Younger patients typically display relative visual field defects, while older patients manifest absolute defects. Individuals with CHRPE, when tested with electroretinography and electro-oculography, tend to show normal results.
Performing a systemic evaluation and genetic counseling is crucial for patients with instances of multiple, atypical CHRPEs. Diseases associated with these types include FAP, Gardner syndrome, and Turcot syndrome. All these conditions involve a mutation in the APC gene and can potentially lead to colon cancer by age 50. Regular testing is needed for these patients and their family members since the conditions are hereditary.
Gardner syndrome is a condition that presents itself with FAP and other tissue tumors, including lipoma, fibroma, and epidermoid cysts, and bone growths. Turcot syndrome, on the other hand, is characterized by brain tumors in association with FAP.
Treatment Options for Congenital Hypertrophy of Retinal Pigment Epithelium
People with solitary Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) or Grouped Pigmentary Retina (GPR) don’t generally need treatment, but it’s a good idea to have these conditions checked from time to time. This is to keep an eye out for the rare occurrence of nodules developing, or the conditions becoming worse or even turning into cancer. An eye care professional might measure the size of the eye spot and also take pictures of the back of your eye to keep track of any changes in size or appearance.
If you have Pigmented Ocular Fundus Lesions (PO-FLs), it’s suggested that you get regular tests called endoscopies from a stomach and bowel specialist. This is to look for growths called polyps in the colon and rectum. If you have a family history of a condition called adenomatous polyposis syndrome, or if you have more than 10 polyps regardless of your family medical history, it might be worth getting genetic testing done. This can not only provide useful information about the frequency of future screenings and what the likely outcome might be, but also pinpoint the exact gene mutation that’s causing the symptoms.
However, whether you have a single CHRPE or multiple CHRPEs, there’s no overall increased risk of systemic disease. This means you probably don’t need any additional tests or referrals to other specialists.
What else can Congenital Hypertrophy of Retinal Pigment Epithelium be?
When trying to diagnose CHRPE (Congenital Hyperplasia of the Retinal Pigment Epithelium), doctors should consider a few other conditions that might look similar.
- A choroidal nevus (a kind of eye freckle) which is not as dark as CHRPE and doesn’t have the same distinct shape.
- Choroidal melanoma (a type of eye cancer) that often appears as raised dark spots with less clear border compared to CHRPE.
- Melanocytoma of the optic nerve head, which usually looks feathery and raised.
- Congenital simple RPE hamartoma, usually seen as a spot at the back of the eye with a clear border.
- Combined hamartoma of the retina and RPE, usually detected in young patients and may cause changes in the retina and pigment.
- Acquired RPE hyperplasia and focal pigmentation which are abnormal growth or dark spots in the eye.
- Black sunburst related to sickle cell retinopathy; dark, starburst-shaped spots caused by a specific type of blood disorder.
- Healed choroiditis or chorioretinitis, which are types of inflammation in the eye.
- Torpedo maculopathy, characterized by a spot that looks like a torpedo, generally found to the side of the central vision area.
- Paving stone degeneration, which usually shows up in the outer edges of the vision area and resembles multiple lesions in the lower parts of the retina
Each condition comes with its unique features, so doctors would distinguish them from CHRPE by observing the characteristics of the lesion and perform further tests if necessary.
What to expect with Congenital Hypertrophy of Retinal Pigment Epithelium
Patients with a single CHRPE or GPR typically don’t experience any symptoms, and these lesions are harmless. They don’t increase the likelihood of developing any systemic disease, and patients generally have a very good prognosis. However, PO-FLs are connected with FAP, a condition which can lead to fatal colon cancer.
As a result, regular eye check-ups and colonoscopies are essential to catch and manage any potential issues with colon polyps or cancer in a timely manner.
Possible Complications When Diagnosed with Congenital Hypertrophy of Retinal Pigment Epithelium
Remarkably, complications related to CHRPE (Congenital Hypertrophy of the Retinal Pigment Epithelium) are very uncommon. When complications do arise, they are typically due to abnormal growths within the CHRPE itself. These growths can spur the formation of fluid underneath the retina, or cause it to detach. A detached retina means that it’s separated from the neural retina, which is essential for vision. These growths, or nodules, may also lead to vitreomacular traction, which reduces central vision.
Another rare likelihood is that the CHRPE cells may transform into benign (adenoma) or cancerous tumours (adenocarcinoma). They would initially appear as small pigmented nodules that grow slowly over time, eventually invading the sensory retina and developing their blood vessels.
Blood vessels carry necessary material to and from the lesion. It is possible for the nodules to remain stable, or they could grow into larger, potentially problematic lesions. In the worst-case scenario, these lesions could cause massive eye inflammation, retinal detachment, and significant vision loss. Therefore, it is crucial for any CHRPE lesions to be monitored over a long period.
Treatments for these conditions include medication designed to halt the formation of new blood vessels, like bevacizumab, or proton beam radiation therapy. Additional complications may include vitreous traction, cataracts, and posterior synechiae (an eye condition where the iris sticks to either the lens or the cornea). However, in cases without complications, medical professionals will usually just monitor them, as there have been no reported instances of metastasis (or cancer spreading).
It is crucial to mention that having a solitary CHRPE does not increase the risk of gastrointestinal cancer.
Potential Complications of CHRPE:
- Abnormal growth within the CHRPE lesion
- Fluid formation and retinal detachment
- Vision reduction due to vitreomacular traction
- Growth of benign or cancerous tumours
- Massive eye inflammation
- Retinal detachment
- Significant vision loss
- Vitreous traction, cataracts, and posterior synechiae
Preventing Congenital Hypertrophy of Retinal Pigment Epithelium
Patients need to be informed about their diagnosis of CHRPE (Congenital Hypertrophy of the Retinal Pigment Epithelium), and the importance of regular eye check-ups. They should be made aware of the possible changes in the condition, but they should also find comfort in knowing that the risk of cancer development is extremely low, especially when there’s only one CHRPE present.
If patients show signs of PO-FLs (Periocular Freckles of the Lid), they need to understand their links with certain syndromes that can affect multiple body systems, which in turn, can increase the risk of colon cancer. These patients should seek further evaluation from a specialist who treats digestive disorders, namely, a gastroenterologist. Regular screening is key as patients with FAP (Familial Adenomatous Polyposis) can develop colon cancer over time.
Patients with FAP should have tests, like sigmoidoscopy or colonoscopy, to check the lower part of the colon and rectum. These tests should be done every 1 to 2 years, starting from 10 to 12 years of age. Additionally, if polyps, or abnormal tissue growths, are found during these tests, they should undergo a colonoscopy. It’s important to note that in many FAP cases, multiple CHRPEs or PO-FLs can be seen. To manage this, patients should follow a regimen of regular eye exams, genetic testing, and colonoscopies.
