Congenital Hypertrophy of the RPE
Congenital hypertrophy of the RPE (CHRPE) is a relatively common congenital lesion. It is characterized clinically as a flat, heavily pigmented circumscribed lesion that varies in diameter (Chapter 17, Fig 17-11). Frequently, with age, central depigmentation may occur in these lesions (lacunae). Histologically, CHRPE is characterized by enlarged RPE cells with densely packed and larger-than-normal melanin granules (Fig 11-6). This benign condition can generally be distinguished from choroidal nevus and melanoma on the basis of ophthalmoscopic features. In rare instances, adenoma and adenocarcinoma of the RPE may develop in CHRPE.
RPE lesions mimicking CHRPE may be present in Gardner syndrome, a subtype of familial adenomatous intestinal polyposis. Histologic study of the RPE changes in Gardner syndrome reveals that they are more consistent with hyperplasia (increase in the number of cells) of the RPE than with hypertrophy. The RPE changes are probably more appropriately termed hamartomas, consistent with the loss of regulatory control of cell growth that results in other soft-tissue lesions in this syndrome. A mutation in the APC gene, which is linked to Gardner syndrome, confers an increased lifetime risk of developing colon polyps, benign tumors, and cancer.
Figure 11-6 In congenital hypertrophy of the RPE (CHRPE), the RPE cells are larger than normal and contain more densely packed melanin granules (arrows) (hematoxylin-eosin [H&E] stain). For clinical images of CHRPE, see Chapter 17, Figure 17-11.
(Courtesy of Hans E. Grossniklaus, MD.)
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.