Choriocapillaris Involvement in Acute Syphilis Posterior Placoid Chorioretinitis is Responsible for Functional Impairment and Points towards an Immunologic Mechanism: A Comprehensive Clinicopathological Approach

Purpose: To evaluate the multimodal imaging of acute syphilitic posterior placoid chorioretinitis (ASPPC) lesions in order to elucidate their pathophysiology which seems to resemble choriocapillaritis as in primary inflammatory choriocapillaropathies such as multifocal choroiditis (MFC) and acute posterior multifocal placoid pigment epitheliopathy (APMPPE). Methods: Charts of patients with ASPPC seen in the Centre for Ophthalmic Specialised Care, Lausanne, Switzerland, were retrieved. Fundus autofluorescence (FAF), spectral domain optical coherence tomography (SD‑OCT), fluorescein angiography (FA), indocyanine green angiography (ICGA), and when available, OCT angiography were analyzed and compared to a case of MFC. Results: One woman aged 58 and 2 men aged 50 and 31 with unilateral ASPPC were analyzed. All had positive syphilis serologies (venereal disease research laboratory [VDRL] and treponema Pallidum hemagglutination assay [TPHA]). Two were human immunodeficiency virus (HIV) positive. Mean best corrected visual acuity was 0.2 ± 0.1 at presentation and 1.0 for all patients 6 weeks later, after antibiotic treatment for neurosyphilis. All had central scotomata with a mean defect (MD) of 12.2 ± 2.6. Six weeks later, MD values were 3.9 ± 1.7. Microperimetry had a mean score of 25/560 at presentation and recovered to a mean of 444/560 6 weeks later. Multimodal imaging features consisted of FA tissue staining, ICGA hypofluorescent choriocapillaris non-perfusion, FAF hyperautofluorescence, and loss of the ellipsoid line in the diseased areas. The findings were consistent and identical in ASPPC and a case of MFC and pointed toward the involvement of the choriocapillaris. Conclusions: Similarities seen in multimodal imaging features in ASPPC and choriocapillaritis highlight the role of the choriocapillaris in the pathophysiologic mechanism of both conditions. Inflammatory choriocapillaris non-perfusion triggered by infectious agents seems to be the common pathway through which the eye is reacting.