From the archives of the AFIP: Pediatric orbit tumors and tumorlike lesions: Neuroepithelial lesions of the ocular globe and optic nerve

Tumors and tumorlike lesions of the globe and optic nerve in children represent a different histologic spectrum than in adults; the imaging appearances of these lesions reflect their pathologic features. Retinoblastoma is a tumor of infancy and the most common intraocular tumor in children. There are heritable and nonheritable forms. The most common clinical finding is leukocoria. The differential diagnoses of this sign include several nonneoplastic lesions: Persistent hyperplastic primary vitreous is a congenital persistence of an embryonic structure causing a retrolental mass. The primitive vasculature may produce a septum in the posterior chamber. Coats disease is a vascular malformation of the retina that produces a lipoproteinaceous subretinal exudate. The vascular malformation enhances with intravenous contrast material, and the fat-containing subretinal exudate does not. Larval endophthalmitis is a granulomatous reaction to the dead or dying larvae of Toxocara canis or T cati. The most important feature that allows differentiation of retinoblastoma from these so-called pseudoretinoblastomas is the presence of calcification in the former. Medulloepithelioma has two histologic forms; the teratoid type may contain calcifications, but it usually arises anteriorly from the ciliary body rather than posteriorly from the retina. Optic nerve glioma is the most common tumor of the optic nerve in children and is frequently associated with neurofibromatosis type 1. These gliomas are usually pilocytic astrocytomas and cause fusiform enlargement of the nerve.