Sequential Spontaneous Resolution of Acute Syphilitic Posterior Placoid Chorioretinitis

Introduction

Ocular involvement in syphilis may occur in the primary, secondary, and tertiary stages of infection, although more commonly encountered in the latter 2 stages (1). Any part of the eye may be affected, but commonly observed is posterior uveitis in the form of chorioretinitis (1). A 14-day therapy with systemic penicillin is essential for prompt control of the infection and to limit substantial retinal damage and irreversible visual loss (2). We report on the spontaneous sequential resolution of acute syphilitic posterior placoid chorioretinitis (ASPPC) in a patient with HIV coinfection.

Materials and Methods

This is a descriptive case report of a 55-year-old patient who was diagnosed with ASPPC first in the left eye and sequentially in the right eye.

Results

A 55-year-old man was referred because of sudden decrease in visual acuity (VA) and suspected maculopathy in his left eye. He had been diagnosed with HIV infection 4 years earlier and was maintained on antiretroviral therapy with good immune recovery (CD4+ T-cell count 204 cells/µL). Vision upon referral was documented to be 6/9 OD and 6/120 OS.

Upon presentation to our clinic 9 days later, VA OD was counting fingers at 1 meter and VA OS was 6/9. Anterior segments and intraocular pressures were normal. There were trace vitreous cells in both eyes. Fundus examination showed a broad yellow–white deep retinal placoid lesion of the right macula. Optic disc and retinal blood vessels were normal. In the left eye there was fine retinal pigment epithelial (RPE) mottling in the macular area (leopard spotting). Fluorescein angiography revealed early central hypofluorescence and progressive late hyperfluorescence in the right macula in the area of the placoid infiltrate (Fig. 1). Spectral-domain optical coherence tomography (SD-OCT) showed a placoid hyperreflective infiltrate in the right macular area between the external limiting membrane (ELM) and Bruch's membrane. Punctate multiple hyperreflective dots were observed in the infiltrate, outer nuclear layer (ONL), and choriocapillaris with minimal intraretinal fluid (IRF) (Fig. 1). In the left eye, fine nodular RPE thickening was observed in the macular area with focal disruption of the inner segment/outer segment junction layer (Fig. 2). The patient asked for systemic workup to be performed on an outpatient basis, and on follow-up visit 10 days later, VA was 6/15 OD and 6/7.5 OS. There was complete resolution of the right macular placoid infiltrate and SD-OCT confirmed the resolution of the hyperreflective infiltrate and IRF but depicted fine RPE nodular thickening (Fig. 2).

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Fig. 1

Left: Red-free image shows a placoid lesion in the right macula. Right: Spectral-domain optical coherence tomography of the right eye at presentation shows a hyperreflective infiltrate in the macular area, well-delineated between the external limiting membrane and Bruch's membrane. Multiple hyperreflective dots are observed in the infiltrate, the outer nuclear layer, and the choriocapillaris. Loss of the inner segment/outer segment junction layer and retinal pigment epithelium granularity are noted temporal to the infiltrate in the upper and lower panels. Intraretinal fluid is also noted in the outer nuclear layer in the lower panel.

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Fig. 2

Upper panel: Spectral-domain optical coherence tomography of the left eye shows fine retinal pigment epithelium nodularity and disruption of inner segment/outer segment junction layer. Lower panel: Spectral-domain optical coherence tomography of the right eye 10 days later shows complete resolution of the outer retinal infiltrate. Fine diffuse retinal pigment epithelium granularity is noted with disruption of inner segment/outer segment junction layer. On the left is the near infrared image showing the characteristic leopard spotting.

Complete blood count was normal. Erythrocyte sedimentation rate was 12 mm/hour, C-reactive protein was 1.46 mg% (normal limit <0.5), and HIV viral load was less than 20 copies/mL. Treponemal and non-treponemal serologic tests were positive, including Venereal Disease Research laboratory test (VDRL 1:64), rapid plasma reagin (1:512), and Treponema pallidum hemagglutination test (1:80). Brain computed tomography scan was normal and cerebrospinal fluid was negative for VDRL. The patient received a 14-day course of IV penicillin G (24 million units/day). Two months later, VA was 6/7.5 in each eye.

Discussion

Acute syphilitic posterior placoid chorioretinitis is a distinctive manifestation of ocular syphilis characterized by the development of a placoid macular deposit in the outer retina. Fundus autofluorescence descriptions (1, 3) suggest it may result from subretinal deposition of RPE-photoreceptor complex material and incomplete phagocytosis of outer segments. Some have suggested that the hyperautofluorescence visible in these patients might be an inflammatory response and immune complex deposition (4, 5).

Conspicuous is the spontaneous sequential resolution encountered in this case despite the lack of initial fundus images documenting ASPPC lesion OS. However, the patient was referred because of maculopathy OS and visual loss that recovered spontaneously over a period of 9 days. The SD-OCT demonstrated RPE nodular thickening in the left macular area that was later observed in the right macula upon resolution of ASPPC. These nodular RPE elevations were described in a large series of ASPPC patients (6) and were found to be characteristic for this subset of patients. The SD-OCT ASPPC findings in the right eye may represent a very early stage of outer retinal involvement preceding the development of nodular RPE lesions. A well-demarcated outer retinal infiltrate was depicted by SD-OCT, delineated by ELM and Bruch's membrane. Hyperreflective punctate spots were also observed in ONL and choriocapillaris. It is reasonable to believe that ocular immune privilege contributed to the spontaneous resolution of ASPPC in this patient, who experienced immune recovery following antiretroviral therapy. The RPE cells are the first line of defense for invading cells from the blood that transgress the blood–retinal barrier (7). Because of this, they are endowed with multiple pathways that lead to downregulation of activated inflammatory cells and with many properties that allow them to act as macrophages. It can be suggested that RPE immunologic characteristics contained the infectious/inflammatory infiltrate in this patient and prevented extension to inner retina and optic disc.

Despite the uniqueness of the present case, the spontaneous ASPPC resolution, and the excellent visual outcome, it remains essential to promptly manage patients with ocular syphilis because of the possible sight-threatening complications and to prevent potentially fatal disease.