Congenital Hypertrophy of the Retinal Pigment Epithelium with lacunae (CHRPE) is a retinal finding often discovered during a routine eye examination. Understanding this diagnosis requires breaking down the technical terminology. This article explains the visual characteristics, diagnostic methods, and long-term management plan for this specific presentation.
What is Congenital Hypertrophy of the Retinal Pigment Epithelium
The Retinal Pigment Epithelium (RPE) is a single layer of cells situated beneath the neurosensory retina. RPE cells support the photoreceptors and maintain healthy vision. They absorb scattered light using the dark pigment melanin, which prevents light reflection that could interfere with clear vision.
The RPE also forms the outer blood-retina barrier, regulating nutrient transport and removing metabolic waste. “Hypertrophy” refers to an enlargement or overgrowth of these pigmented RPE cells in a localized area. This results in a flat, pigmented spot that is present from birth, which is the meaning of “congenital.”
The descriptor “with lacunae” refers to distinct, depigmented areas within the larger pigmented lesion. A lacuna means a gap or missing part, signifying spots where RPE cells have lost pigment or become atrophied. These areas of depigmentation are essentially windows within the lesion, creating the characteristic appearance that distinguishes this CHRPE variant.
Visual Characteristics and Clinical Appearance
CHRPE with lacunae appears as a sharply demarcated, flat lesion on the fundus (interior surface of the eye). The lesion is dark, ranging from gray-brown to black, due to dense melanin accumulation in the hypertrophied RPE cells. It is typically round or oval with scalloped margins and is most often found in the peripheral retina, away from the central macula.
The lacunae subtype is recognized by distinct, depigmented spots scattered across the dark lesion. These spots are discrete, punched-out areas of RPE atrophy where the underlying choroid may be visible. Multiple, smaller CHRPE lesions clustered together with these spots are often described as having a “bear track” appearance. Solitary CHRPE with lacunae is usually unilateral, found in only one eye. Multiple, bilateral, or atypical lesions may prompt a thorough systemic investigation.
Differentiation from Malignant Lesions
CHRPE with lacunae must be differentiated from potentially life-threatening pigmented lesions, such as choroidal melanoma. Melanoma is the most common primary intraocular malignancy in adults, and its early stages can sometimes mimic benign findings. CHRPE is distinguished by its flat profile, sharp borders, and congenital nature, implying long-term stability.
Malignant lesions like melanoma are typically elevated, often presenting as a dome or mushroom shape, and are usually thicker than two millimeters. Specialized imaging confirms the benign nature of CHRPE. Optical Coherence Tomography (OCT) creates cross-sectional images, showing that CHRPE is flat and involves only a thickening of the RPE layer.
OCT shows the lacunae areas lack the RPE layer and overlying photoreceptor cells, consistent with atrophy rather than tumor growth. Fundus Autofluorescence (FAF) imaging confirms the diagnosis: the dark, hypertrophied portions show hypo-autofluorescence because dense RPE pigment blocks underlying fluorescence. A solitary CHRPE is non-progressive and does not transform into a malignant tumor.
Association with Systemic Conditions
A less common variant of CHRPE, involving multiple, small lesions present in both eyes, has been associated with Familial Adenomatous Polyposis (FAP) and Gardner’s syndrome. These genetic conditions significantly increase the risk of developing colorectal cancer. When this atypical presentation is identified, the eye finding serves as a marker necessitating a comprehensive systemic evaluation, including consultation with a gastroenterologist and genetic counseling. However, the vast majority of solitary CHRPE with lacunae are not associated with these syndromes and pose no systemic health risk.
Long-Term Outlook and Management
The prognosis for solitary CHRPE with lacunae is excellent, as the lesion is asymptomatic and benign. Since it is typically located in the peripheral retina, it rarely affects central visual acuity or causes noticeable symptoms. Even if the lacunae appear to enlarge slowly over many years, the lesion remains stable and does not compromise vision.
Management centers on observation rather than active treatment, as CHRPE does not typically progress or cause functional issues. The primary goal is to monitor the lesion for rare changes in size, shape, or elevation. Monitoring is accomplished through routine dilated eye examinations, often supplemented with baseline and follow-up fundus photography to document stability.
Eye care professionals usually recommend routine follow-up examinations every one to two years. Patients should seek prompt care if they notice new visual symptoms, such as sudden flashes of light, new floaters, or a shadow in the vision. For those with the atypical, multiple-lesion presentation, adherence to systemic screenings, such as colonoscopies, is a necessary part of ongoing management.