Overview
- Definition
Ocular syndrome of peripheral punched out chorioretinal lesions (histo spots), peripapillary atrophy, macular scarring with or without choroidal neovascular membranes and absence of vitritis
- Presumed exposure to the dimorphic fungus Histoplasma capsulatum
Grows in soil (mold) and inside animals/birds (yeast)
Endemic in valleys of Ohio and Mississippi Rivers, the “Histo belt”
- Symptoms
Asymptomatic mostly
Scotomas
Blurring
Metamorphopsia
Rarely photopsias
- Laterality
Typically unilateral, bilateral in up to 12%
- Course
Chronic, indolent
Acute symptomatic onset of secondary complications, choroidal neovascular membrane (CNV)
- Age of onset
Median age 36, may be present much earlier undetected
- Gender/race
- No gender or racial predilection of overall disease
Disciform macular type more common in Caucasians
Bilateral more common in men
- Systemic association
Not in association with disseminated systemic histoplasmosis
Exam: Ocular
Anterior Segment
No associated findings
Posterior Segment
Clear vitreous
- Disseminated choroiditis, “histo spots,” 4–8 per eye
- Typical (inactive)
- Small, circular depigmented and atrophic chorioretinal scars
0.2–0.7DD, “punched-out” lesions
Mid-periphery and posterior to the equator
+/− central pigmented clump
- Atypical (active)
Creamy yellow lesions, slightly elevated, in mid-periphery
More prone to develop CNV
- Linear streaks (5% of patients)
Typical spots near equator that run in linear patterns parallel to the ora serrata
- Maculopathy, disciform macular scar
- Old raised fibrovascular scar in macula, often a result of CNV
Or can be similar to histo spots
Active lesions at the edge of old lesions
- Peripapillary chorioretinal degeneration
Pigmented changes typical
+/− CNV in 11%
- Less common
Subretinal hemorrhage
Vitreous hemorrhage
- “Disappearing lesions”
Histo spots may spontaneously resolve
Exam: Systemic
None
Imaging (Only the Relevant Ones)
OCT: disruption of external limiting membrane (ELM), ellipsoid and retinal pigment epithelium (RPE)/Bruch’s membrane; pigment epithelial detachment (PED); CNV
FAF: may detect small, nonpigmented macular chorioretinal scars
FA: Classic CNV findings; window defects; active lesions show late hyperfluorescence
ICG: increased hypercyanescence in affected choriocapillaris
Laboratory and Radiographic Testing
Clinical diagnosis based on exam findings
Chest X-ray, CT
- Serologic testing
- Ancillary testing performed historically
Histoplasmin skin test
Histoplasma complement fixation test
HLA-B7 association
Differential Diagnosis
- White dot syndromes
Multifocal choroiditis and panuveitis (MCP)
Punctate inner choroidopathy (PIC)
Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)
Multiple evanescent white dot syndrome (MEWDS)
Idiopathic choroidal neovascularization
Age-related macular degeneration
Choroidal rupture
Angioid streaks
Central serous retinopathy
Myopic degeneration
Peripapillary coloboma
Sarcoidosis
Toxoplasmosis
Treatment
- Corticosteroids for active lesions
Systemic or periocular
Intraocular anti-vascular endothelial growth factor (VEGF) agents or photodynamic therapy (PDT) for subfoveal and juxtafoveal CNV
Laser photocoagulation for extrafoveal CNV
- Subretinal surgery not routinely performed for submacular CNV
High recurrence afterward
Referral/Co-management
None typical