Background: Retinoblastoma (RBS) is the most frequent primary intraocular tumor in children. Nowadays, combining modern therapeutic methods over 95% survival rate can be achieved.
Case Report: Authors describe a 2,5-year-old boy F.Z., whose eye was enucleated because of intraocular tumour infiltrating an optic nerve. On clinical examination and imaging (US – ultrasonography, CT – computed tomography, MRI – magnetic resonance imaging) he was misdiagnosed as retinal detachment, endophthalmitis, optic nerve glioma and multiple meningiomas. The boy died because of extensive metastases to central nervous system. On histopathological examination of the enucleated eye the diagnosis of retinoblastoma non-differentiatum was established.
Conclusions: Authors suggest that it is important to remember, that some types of low differentieted tumors don’t present typical calcifications despite large tumor mass.

Keywords: Retinoblastoma, misdiagnosis, Endophthalmitis, Optic Nerve Glioma