Clinical and electron microscopic features of retinoblastoma.

A male child of 1-year, 6-month-old had a history of leukocoria of the left eye for approximately three months prior to admission into our facility. No abnormality was found in the right eye. There was negative family history of retinoblastoma. Ophthalmoscopy revealed a white mass extending from the supero-posterior part of the left globe to the posterior surface of the lens. Orbital tomograms showed no intraocular tissue densities in the mass but a B-scan ultrasound showed an echo dense area of the mass. Histopathologically areas of photoreceptor differentiation and Flexner-Wintersteiner rosettes were observed in the tumor mass by light microscope. Transmission electron microscopy disclosed the presence of prominent mitochondria on the luminal side of the cells forming rosettes and these were believed to be the component parts of the inner-segments of the photoreceptor cells. The results of this study indicate a predominant neuronal nature of the neoplastic cells with photoreceptor-like differentiation.