OSLI Retina

April 2020

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236 Ophthalmic Surgery, Lasers & Imaging Retina | Healio.com/OSLIRetina ■ C A S E R E P O R T ■ Congenital Grouped Albinotic Spots: New Insights on the Pathophysiology Based on Multimodal Retinal Imaging João Pedro Marques MD, MSc, FEBO; Emmanuel Rebelo Neves MD, MSc; Cláudia Farinha MD, MSc; Rufino Silva MD, PhD ABSTRACT: The terms "congenital grouped albinot- ic spots" (CGAS) and "polar bear tracks" refer to a rare, benign retinal disorder of unknown etiology characterized by multiple, predominantly unilat- eral, variably sized, well-circumscribed, flat white retinal spots organized in groups. To date, very few cases of CGAS have been reported. The authors de- scribe a case of CGAS thoroughly characterized by multimodal imaging over an 8-year follow-up, aim- ing to provide new insights on the pathophysiology of this entity. This is the first report where a long follow-up combined with up-to-date imaging tech- nology is used to characterize CGAS. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:236-238.] INTRODUCTION The term "congenital grouped albinotic spots" (CGAS) defines a rare clinical entity first described by Gass in 1989. 1 It is characterized by multiple, predom- inantly unilateral, variably sized, well-circumscribed, flat, white retinal spots organized in groups. Their peculiar distribution resembling animal footprints reminds grouped/multifocal congenital hypertrophy of the retinal pigment epithelium (CHRPE) or bear tracks. However, due to the albinotic appearance, the term "polar bear tracks" became a synonym of CGAS. CGAS has been considered an incidental finding, but little is known about the natural history or patho- physiology. In the original description, Gass 1 specu- lated that it would originate from focal changes on the retinal pigment epithelium (RPE), where the accu- mulation of a white material, possibly a precursor of melanin, would be deposited. However, this has nev- er been confirmed histologically. Several authors 2-5 have described imaging findings in CGAS, namely in fluorescein angiography, indocyanine green angiogra- phy and fundus autofluorescence (FAF) but detailed tomographic findings are missing. Improvements in optical coherence tomography (OCT) technology and the recent introduction of OCT angiography (OCTA) have reshaped our knowledge of retinal diseases. We describe a case of CGAS thoroughly characterized by multimodal imaging over an 8-year follow-up, aim- ing to provide new insights on the pathophysiology of CGAS. CASE REPORT A 26-year-old asymptomatic male was referred for laser refractive surgery. Other than mild myopia (–1.75 in the right eye [OD] and –2.00 in the left eye [OS]), no relevant history was present. Fundus ex- amination revealed several pale spots in the tempo- ral macula and midperiphery OD (Figure 1), whereas the left eye was normal. On fundus autofluorescence (FAF), the grouped albinotic spots appeared hypoau- tofluorescent and resembled animal footprints. Strik- ingly, FAF revealed a greater number of spots than fundus examination (Figure 1). OCT scans over the spots showed absence of the outer retinal layers but an apparently intact subjacent RPE (Figure 2). On OCTA, focal changes could be observed on the cho- riocapillaris layer (Figure 3). Electrophysiology was normal in both eyes. After 8 years of follow-up, no significant changes were recognized. DISCUSSION CGAS is a rare, benign retinal disorder of unknown etiology. To date, very few cases of CGAS have been From the Department of Ophthalmology, Centro Hospitalar e Universitário de Coimbra (CHUC), Coimbra, Portugal (JPM, ERN, CF, RS); and the Faculty of Medicine, University of Coimbra (FMUC), Coimbra, Portugal (JPM, CF, RS). Originally submitted August 15, 2019. Revision received February 16, 2020. Accepted for publication February 25, 2020. Drs. Marques and Neves contributed equally to this manuscript as co-first authors. The authors report no relevant financial disclosures. Address correspondence to João Pedro Marques MD, MSc, FEBO, Centro de Responsabilidade Integrado em Oftalmologia (CRIO), Centro Hospitalar e Universitário de Coimbra (CHUC), Praceta Prof. Mota Pinto, 3000-075 Coimbra, Portugal; email: marquesjoaopedro@gmail.com. doi: 10.3928/23258160-20200326-05

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