Histopathologic Findings in Congenital Grouped Pigmentation of the Retina

Background: Congenital grouped pigmentation of the retina is a condition characterized by multiple, well-circumscribed, flat, pigmented fundus lesions clustered in a fashion resembling “bear tracks.” Methods: Light and electron microscopy was used to study these lesions in an eye of a 2-year-old boy. The eye was enucleated for retinoblastoma. Results: Similar to the classic, solitary, congenital hypertrophy of the retinal pigment epithelium (CHRPE), the involved RPE cells contained an increased number of large pigment granules. Unlike CHRPE, most pigment granules retained the normal ellipsoidal shape. In addition, hypertrophy and hyperplasia of the RPE cells were not significant features by light and electron microscopy. Conclusion: Although the lesions in this case superficially resembled CHRPE by light microscopy, ultrastructural differences were identified.