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A 56-year-old man with a unilateral central scotoma
Digital Journal of Ophthalmology 2021
Volume 27, Number 3
September 27, 2021
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Khushali Shah, BA | University of Miami Miller School of Medicine, Miami, Florida; Bascom Palmer Eye Institute, Miami, Florida Benjamin J. Fowler, MD, PhD | Bascom Palmer Eye Institute, Miami, Florida Benjamin Lin, MD | Bascom Palmer Eye Institute, Miami, Florida Kara M. Cavuoto, MD | Bascom Palmer Eye Institute Jayanth Sridhar, MD | Bascom Palmer Eye Institute, Miami, Florida
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| Diagnosis and Discussion | Syphilis, caused by the spirochete Treponema pallidum may mimic myriad other clinical presentations. In the United States, men who have sex with men represent 67% of syphilis cases.(3) Ocular manifestations of syphilis appear in 5%-8% of individuals with the highest frequency in secondary and tertiary stages of syphilis.(5,6) Patients with ocular syphilis typically present with posterior uveitis; chorioretinitis has been cited as the most common posterior segment manifestation.(7) ASPPC, first described by Gass et al,(8) is a rare but distinctive form of posterior segment ocular syphilis, characterized by acute loss of visual acuity and placoid macular lesions in the outer retina. Only 3% of those with ocular syphilis are diagnosed with ASPPC.(6) Epidemiologically, 90% of individuals affected are middle-aged men, with a mean age in the mid-40s, and almost half of diagnosed patients have a history of secondary syphilis with mucocutaneous expression.(4)
The pathophysiology of ASPPC is not completely understood. One proposed mechanism is an inflammatory or immune-complex mediated reaction.(2) Studies have described an inflammatory origin at the level of the choroid-RPE-photoreceptor complex. Moll-Udina et al have proposed the choriocapillaries as the site of inflammation in ASPPC, because multimodal optical coherence tomography angiography (OCTA) demonstrates large areas of nonperfusion in this vascular layer.(9) This lack of blood flow can predispose the retina to further damage in the photoreceptor and RPE layers if left untreated. OCTA has been a useful tool to capture the reversible disruption of choriocapillaris flow in ASPPC.(10) These abnormalities may be transient upon diagnosis but typically resolve with early treatment.(10) First proposed by Gass et al and corroborated by multiple studies, T. pallidum is thought to enter the eye via choroidal circulation and most significantly affects the macula, where the choroidal vascular supply is the greatest.(3) Indocyanine green angiography has been a useful imaging modality, highlighting the choriocapillaris flow void and typically demonstrating hypofluorescence in the lesion sites.(11-13) Excellent functional outcome with outer retinal recovery is achievable if ASPPC is recognized and treated promptly with systemic penicillin therapy.
Hallmark imaging findings of ASPPC include FAF demonstrating localized hyperautofluorescence in the area of the placoid lesion secondary to sub-RPE deposits and inadequate phagocytic removal of outer segments.(3) These hyperautofluorescent areas on FAF colocalize with sub-RPE deposits seen on OCT; it has been suggested that this represents accumulation of lipofuscin at the level of the RPE-photoreceptor complex.(5) Other studies propose that these accumulations are collections of fibrin, platelets, and/or inflammatory cellular debris.(3) Our patient presented with discontinuity of the RPE, EZ, and photoreceptor layers; more severe findings in ASPPC include the accumulation of subretinal fluid and loss of external limiting membrane.(14) Shallow serous retinal detachment on OCT has also been described in patients with ASPPC.(3)
Prompt diagnosis with an initial screen of FTA-ABS, followed by non-treponemal RPR titers and HIV testing, are essential to guide treatment decisions and management in ASPPC.(1,4,9) The Centers for Disease Control and Prevention guidelines recommend that patients with ocular syphilis should undergo lumbar puncture with cerebrospinal fluid examination and be treated for neurosyphilis.(15) In our case, the admitting infectious disease team opted toward treating for neurosyphilis without lumbar puncture, because it would not have changed management. Up to 30%-60% of ocular syphilis patients may be coinfected with HIV.(1,4,9) Although HIV patients historically have been at higher risk of developing more severe forms of ocular syphilis, a study by Pichi et al demonstrated the presence of ASPPC in more than two-thirds of HIV negative, immunocompetent patients.(1,9) Previous studies have reported no differences in vision improvement after therapy with respect to HIV status. Our patient tested negative for HIV.
Several interventional and mechanistic studies have shed light on the pathogenesis of ASPPC. Some studies support an autoimmune etiology of the condition and cite higher levels of anti-beta 2 glycoprotein antibodies in patients with ASPPC, with the potential to cause focal choroidal thrombosis and photoreceptor damage.(1,2) Sahin et al reported that the use of methotrexate in ocular syphilis was beneficial as an adjuvant therapy to penicillin, causing decreased intraocular inflammation and cystoid macular edema.(16) In contrast, others have reported that long- and short-term corticosteroid use is associated with progression of ASPPC, suggesting that immune suppression may be a risk factor for ASPPC.(4,8,17) Thus, competing theories contend that ASPPC lesions may arise from a direct attack by T. pallidum as a result of reactivation from immunosuppression or, alternatively, may be a consequence of indirect immune-mediated hypersensitivity.(2) Prompt recognition and early treatment are essential in preventing and reversing vision loss in patients with ASPPC. Future studies with clinic-histopathologic correlation may help augment our understanding of the pathogenesis of ASPPC.(3) | |
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