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Ophthalmology – Congenital Hypertrophy of the Retinal Pigmented Epithelium (CHRPE)
Congenital Hypertrophy of the Retinal Pigmented Epithelium (CHRPE) consists of benign melanocytic lesions of the retinal pigment epithelium (RPE). These lesions may be solitary, grouped, or multiple, and their clinical significance ranges from harmless incidental findings to markers of systemic disease.
CHRPE lesions are typically flat, well-demarcated, and darkly pigmented, appearing gray-brown to jet black. Many lesions show characteristic depigmented lacunae (pale areas) or a surrounding halo. They are most commonly located in the superotemporal fundus and usually measure about 1–2 disc diameters, though larger lesions can occur.
Three main patterns are recognized:
1. Solitary CHRPE
These are single, flat lesions with smooth or scalloped borders. They may slowly enlarge over time and can develop increasing depigmentation. They are generally benign and not associated with systemic disease.
2. Grouped CHRPE (“bear tracks”)
These consist of multiple small, round pigmented spots arranged in clusters. They are often unilateral and confined to one retinal quadrant. Despite their striking appearance, they have no systemic associations and are considered benign variants.
3. Multiple bilateral CHRPE associated with Familial adenomatous polyposis
This pattern is clinically important. Lesions are typically:
• Multiple (>4 per eye)
• Bilateral
• Oval with irregular borders
• Often show “fishtail” depigmentation at the edges
These findings may indicate an underlying mutation in the APC gene, a tumor suppressor gene responsible for familial adenomatous polyposis (FAP).
Epidemiologically, CHRPE is found in approximately 1.2% of the population, while FAP occurs in about 1 in 13,000–18,000 individuals. Notably, 70–80% of patients with FAP have CHRPE-like lesions, making this an important ocular marker.
Pathophysiologically, CHRPE arises from hypertrophy and hyperplasia of RPE cells, which contain abundant melanin. Solitary and grouped lesions are typically composed of a single layer of enlarged pigmented cells, while FAP-associated lesions may show multilayering and retinal involvement.
History is crucial, especially in patients with multiple lesions. Clinicians should ask about:
• Family history of colon cancer or polyps
• Gastrointestinal symptoms (e.g., rectal bleeding, abdominal pain)
• Associated tumors or syndromes
On examination, dilated funduscopy reveals the characteristic pigmented lesions. The presence of bilateral, multiple, widely spaced lesions should raise suspicion for FAP and prompt systemic evaluation.
Diagnostic tools include:
• Fundus photography for documentation and monitoring
• Autofluorescence imaging (lesions appear hypoautofluorescent)
• Fluorescein angiography (may show capillary changes)
• Visual field testing (for large lesions causing scotomas)
If FAP is suspected, referral for genetic testing (APC gene) and gastrointestinal evaluation is essential. Screening with colonoscopy or sigmoidoscopy typically begins in childhood (around age 10).
Management depends on the type:
• Solitary and grouped CHRPE: No treatment required; routine observation
• FAP-associated CHRPE: Requires systemic surveillance and management, including possible colectomy depending on polyp burden
Follow-up includes periodic ophthalmic examination with photographic documentation to monitor for growth or changes.
Prognosis for isolated CHRPE is excellent. Lesions may enlarge slowly and can cause localized retinal atrophy, occasionally leading to visual field defects.
The most critical complication is not ocular but systemic--risk of colorectal carcinoma in patients with FAP. Rarely, malignant transformation of CHRPE itself has been reported, but this is exceedingly uncommon.
Congenital Hypertrophy of the Retinal Pigmented Epithelium (CHRPE) consists of benign melanocytic lesions of the retinal pigment epithelium (RPE). These lesions may be solitary, grouped, or multiple, and their clinical significance ranges from harmless incidental findings to markers of systemic disease.
CHRPE lesions are typically flat, well-demarcated, and darkly pigmented, appearing gray-brown to jet black. Many lesions show characteristic depigmented lacunae (pale areas) or a surrounding halo. They are most commonly located in the superotemporal fundus and usually measure about 1–2 disc diameters, though larger lesions can occur.
Three main patterns are recognized:
1. Solitary CHRPE
These are single, flat lesions with smooth or scalloped borders. They may slowly enlarge over time and can develop increasing depigmentation. They are generally benign and not associated with systemic disease.
2. Grouped CHRPE (“bear tracks”)
These consist of multiple small, round pigmented spots arranged in clusters. They are often unilateral and confined to one retinal quadrant. Despite their striking appearance, they have no systemic associations and are considered benign variants.
3. Multiple bilateral CHRPE associated with Familial adenomatous polyposis
This pattern is clinically important. Lesions are typically:
• Multiple (>4 per eye)
• Bilateral
• Oval with irregular borders
• Often show “fishtail” depigmentation at the edges
These findings may indicate an underlying mutation in the APC gene, a tumor suppressor gene responsible for familial adenomatous polyposis (FAP).
Epidemiologically, CHRPE is found in approximately 1.2% of the population, while FAP occurs in about 1 in 13,000–18,000 individuals. Notably, 70–80% of patients with FAP have CHRPE-like lesions, making this an important ocular marker.
Pathophysiologically, CHRPE arises from hypertrophy and hyperplasia of RPE cells, which contain abundant melanin. Solitary and grouped lesions are typically composed of a single layer of enlarged pigmented cells, while FAP-associated lesions may show multilayering and retinal involvement.
History is crucial, especially in patients with multiple lesions. Clinicians should ask about:
• Family history of colon cancer or polyps
• Gastrointestinal symptoms (e.g., rectal bleeding, abdominal pain)
• Associated tumors or syndromes
On examination, dilated funduscopy reveals the characteristic pigmented lesions. The presence of bilateral, multiple, widely spaced lesions should raise suspicion for FAP and prompt systemic evaluation.
Diagnostic tools include:
• Fundus photography for documentation and monitoring
• Autofluorescence imaging (lesions appear hypoautofluorescent)
• Fluorescein angiography (may show capillary changes)
• Visual field testing (for large lesions causing scotomas)
If FAP is suspected, referral for genetic testing (APC gene) and gastrointestinal evaluation is essential. Screening with colonoscopy or sigmoidoscopy typically begins in childhood (around age 10).
Management depends on the type:
• Solitary and grouped CHRPE: No treatment required; routine observation
• FAP-associated CHRPE: Requires systemic surveillance and management, including possible colectomy depending on polyp burden
Follow-up includes periodic ophthalmic examination with photographic documentation to monitor for growth or changes.
Prognosis for isolated CHRPE is excellent. Lesions may enlarge slowly and can cause localized retinal atrophy, occasionally leading to visual field defects.
The most critical complication is not ocular but systemic--risk of colorectal carcinoma in patients with FAP. Rarely, malignant transformation of CHRPE itself has been reported, but this is exceedingly uncommon.
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