2020–2021 BCSC Basic and Clinical Science Course™
4 Ophthalmic Pathology and Intraocular Tumors
Part I: Ophthalmic Pathology
Chapter 11: Retina and Retinal Pigment Epithelium
See BCSC Section 12, Retina and Vitreous, for additional discussion of macular dystrophies.
Fundus flavimaculatus and Stargardt disease
Fundus flavimaculatus and Stargardt disease are thought to represent opposite ends of an inherited disease spectrum characterized by yellowish flecks at the RPE level, a generalized vermilion (reddish) fundus clinically, variable late RPE atrophy, dark choroid on FA, and gradually decreasing vision (Fig 11-38; see also Fig 13-11 in BCSC Section 12, Retina and Vitreous). The inheritance pattern is generally autosomal recessive, but autosomal dominant forms have been reported. The most striking feature of Stargardt disease revealed by light and electron microscopy is the marked engorgement of RPE cells with lipofuscin-like, PAS-positive material and apical displacement of the normal RPE melanin granules (see Fig 11-38D; see also Fig 13-12 in BCSC Section 12, Retina and Vitreous).
The term pattern dystrophies refers to a heterogeneous group of inherited disorders characterized by varying patterns of pigment deposition in the macular RPE. The most common genetic mutation associated with the pattern dystrophies occurs in the PRPH2 (peripherin 2) gene. Recognized pattern dystrophies include butterfly-shaped pattern dystrophy (BPD), adult-onset foveomacular vitelliform dystrophy (AFMVD), reticular dystrophy, and fundus pulverulentus. BPD is characterized by an irregular, butterfly-shaped, depigmented lesion at the RPE level. AFMVD is characterized by slightly elevated, symmetric, round-to-oval yellow lesions at the RPE level; these lesions are typically smaller than the vitelliform lesion characteristic of Best disease (Fig 11-39).
Figure 11-36 Polypoidal choroidal vasculopathy. A, Peripapillary dilated vascular channels (arrow) between the RPE and the outer aspect of Bruch membrane (arrowheads). Note the dense subretinal hemorrhage (asterisk). ON = optic nerve. B, Higher-magnification view of thin-walled vascular channels (asterisks) interposed between the RPE (arrow) and the Bruch membrane (arrowhead).C, Hemorrhagic RPE detachments (arrow) and serosanguineous subretinal fluid (asterisk).
(Courtesy of Robert H. Rosa Jr, MD.)
Spectral-domain optical coherence tomography (SD-OCT) in patients with pattern dystrophy reveals elevation of the photoreceptor layer, with localization of the dystrophic material between the photoreceptors and RPE (see Fig 11-39C). Histologic studies reveal central loss of the RPE and photoreceptor cell layer with a moderate number of pigment-containing histiocytes (macrophages) in the subretinal space and outer neurosensory retina (see Fig 11-39D). The adjacent RPE is distended with lipofuscin (see Fig 11-39E). Basal laminar and linear deposits may be present throughout the macular region. The pathologic finding of pigment-containing cells with lipofuscin and drusenlike material in the subretinal space correlates with the vitelliform pattern seen clinically.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.