Clinical History
Right sided leukokoria associated with cataract formation, decreased vision on the right globe, and motor mental retardation.
Imaging Findings
A 21 moth-old male patient was referred to our MRI unit with the findings of right sided leukokoria associated with cataract formation, decreased or probably no vision on the right globe, and motor mental retardation. T1- weighted spin-echo, T2-weighted fast spin echo and FLAIR (fluid attenuated inversion recovery) images of the bilateral orbita were obtained on three planes with 3-mm slice thickness on a 1.5 T MR scanner.
Discussion
Persistent hyperplastic primary vitreous (PHPV) is a rare developmental condition characterized by persistence and proliferation of embryonic hyaloid vascular system of primary vitreous due to arrest of normal regression. PHPV is a unilateral disorder in a microphthalmic eye, seen in full-term infants. PHPV rarely is bilateral in patients with Norrie's disease, Warburg syndrome, or patients with retinal dysplasia. Primary vitreous is a fibrillar ectodermal meshwork and mesodermal tissue consisting of embryonic hyaloid vascular system, it appears during first month of life, and extends between lens and retina. Primary vitreous involutes by 6th month of gestation. Hyaloid artery is important source of intraocular nutrition, supplying vitreous and posterior aspect of the lens. Secondary or adult vitreous begins to form during 3rd gestational month, a watery mass of loose collagen fibers and hyaluronic acid gradually replaces primary vitreous, which is reduced to a small S-shaped remnant called hyaloid canal (Cloquet canal) and serves as lymph channel. PHPV is the second most common cause of leukokoria. The patients with PHPV can have seizures, mental deficiency, hearing loss as associated findings. Cataract formation is a common complication of PHPV. The diagnosis is generally put by an ophthalmoscopic examination of the patient, revealing S-shaped tubular mass extending between posterior surface of the lens and region of optic nerve head, however lens opacity may preclude the diagnosis. Ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI) are the radiologic diagnostic tools. , s until 8th month of gestation. Persistent fetal vasculature leads to fibrosis, resulting in elongation of the ciliary processes, retinal detachment, and spontaneous cataracts. The CT appearance in the disorder is quite variable; however, MR imaging may be superior in demonstrating the enhancing retrolental mass and the elongated ciliary processes. The vitreous body can be hyperintense both in T1 and T2 weighted sequences due to chronic blood degradation products and proteinaceous fluid on MRI pictures of PHPV. A hypointense or isointense thin triangular band with its base near the optic disk and its apex at the posterior surface of lens is characteristic MRI appearance, this band shows marked contrast enhancement. Microphthalmia, small optic nerve, deformity of globe and lens are the other associated findings.
Differential Diagnosis List
Persistent hyperplastic primary vitreous
Final Diagnosis
Persistent hyperplastic primary vitreous
