Summary of Comprehensive Overview of Choroidal Diseases
Comprehensive Overview of Choroidal Diseases for Students
Introduction
Choroidal tumors are lesions arising from the choroid, the vascular layer between the retina and the sclera. They range from benign nevi to malignant melanomas and have important diagnostic, prognostic, and therapeutic implications. This guide focuses on choroidal nevi, choroidal melanoma, and circumscribed and diffuse choroidal hemangiomas, their presentation, diagnostic approach, and management.
Definition: The choroid is the vascular tissue between retina and sclera; choroidal tumors are focal proliferations or masses within this layer that may be benign or malignant.
Choroidal Nevus
Epidemiology & natural history
- Prevalence ~5% of the population. More common in people of European descent; rare in darkly pigmented races.
- Typically develops in early life and grows during adolescence/early adulthood. New growth in older adults is suspicious.
- Benign lesion; usually flat and minimally elevated (never >2 mm thickness).
Definition: Choroidal nevus — a benign, usually flat pigmented lesion of the choroid composed predominantly of spindle melanocytes.
Clinical features
- Color: commonly green/grey but can be light brown or amelanotic.
- Size: typical diameter 1–5 mm; critical threshold is 5 mm (diameter) — lesions >5 mm are highly suspicious for melanoma.
- Thickness: usually ≤2 mm; >2 mm is suspicious.
- Borders: may be distinct or indistinct; border appearance alone is unreliable.
- Associations: drusen or RPE pigment clumping over the lesion; spindle-cell histology is typical and favorable.
Diagnostic testing
- Red/green filters: red penetrates the choroid and highlights choroidal lesions; green filter does not penetrate well.
- Fundus photography: baseline documentation and interval comparison.
- Fluorescein angiography (FA): typically hypofluorescent (choroid appears dark) for nevus.
- B-scan ultrasound: hyperreflective and flat; choroidal vasculature preserved; no posterior shadowing/excavation.
Follow-up and management
- Initial follow-up every 6–12 months; many clinicians review twice yearly to document stability.
- Monitor for growth, new subretinal fluid, orange pigment, or increased thickness.
Differential diagnosis highlights
- Melanoma: distinguished by larger size, elevation, documented growth, orange pigment, subretinal fluid, and choroidal excavation on B-scan.
- CHRPE: use red/green filter to differentiate.
Choroidal Melanoma
Epidemiology & pathophysiology
- Incidence roughly 1 per 2,000 persons. Typically arises in middle age or older adults (≥35–40 years) and is rare in children.
- Predominantly affects white patients; no strong sex predilection.
- Arises from melanocytes; histology includes spindle cells and epithelioid cells. A higher proportion of epithelioid cells confers worse prognosis.
- Chromosomal abnormalities (e.g., chromosome 3 loss, chromosome 8 alterations) correlate with metastatic risk.
Definition: Choroidal melanoma — a malignant melanocytic tumor of the choroid with potential for local destruction and distant metastasis, most commonly to the liver.
Clinical presentation and signs
- Visual symptoms: often asymptomatic; vision loss occurs if subretinal fluid, retinal detachment, or macular involvement is present.
- Appearance: color varies from dark grey/green to light brown; amelanotic variants exist.
- Size: diameter >5 mm and thickness >2 mm are red flags. Very large tumors (>12 mm diameter or >8 mm thickness) often require enucleation.
- Shape: dome-shaped, mushroom/collar-stud (when breakthrough through Bruch/RPE), or flat; margins commonly indistinct.
- Characteristic associated signs:
- Orange pigment (lipofuscin) on surface — highly suggestive of melanoma.
- Subretinal fluid/serous detachment is common.
- Intrinsic tumor vessels that appear to "jump" on the elevated l
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Choroidal Tumors Overview
Klíčové pojmy: Choroidal nevus: common (~5%), typically flat, diameter 1–5 mm, thickness ≤2 mm, monitor every 6–12 months, Melanoma red flags: diameter >5 mm, thickness >2 mm, subretinal fluid, orange pigment, documented growth, TFSOM mnemonic: Thickness >2 mm; Fluid; Symptoms; Orange pigment; Melanoma hollow (excavation), B-scan distinction: melanoma shows posterior shadow/excavation; nevus and hemangioma do not, FA patterns: melanoma shows early hyperfluorescence with late leakage; metastasis often early hypo then late hyper without leakage, Circumscribed hemangioma: orange mass, elevated (~3–4 mm), uniformly hyperreflective on B-scan, minimal leakage on FA, Diffuse hemangioma associated with Sturge–Weber syndrome and high glaucoma risk, Treatment selection depends on size, thickness, location, patient factors: options include plaque brachytherapy, proton beam, TTT, local excision, enucleation, Document baseline imaging (photo, OCT, B-scan) and compare serial images to detect growth, Chromosomal abnormalities (chromosome 3, 8) and epithelioid cell proportion predict melanoma metastasis risk