Retinoblastoma which developed in microphthalmia.

We report a rare case of retinoblastoma which developed in unilateral microphthalmia. A 4-year-old girl presented with a large, intraocular mass in microphthalmia without a family history of retinoblastoma. The eyeball was enucleated due to rapid growth of the intraocular tumor. Microscopically it proved to be a retinoblastoma with some Flexner-Wintersteiner rosettes. This unusual case shows that retinoblastoma should not be excluded just because the eye is small, particularly if the family history is not available or is incomplete.