Molecular analysis confirms retinoblastoma diagnosis in a histologically undifferentiated retinal tumor in an adult.

Retinoblastoma is the most common pediatric intraocular cancer. Rarely, it may develop in adults, with different clinical and imaging characteristics that make the diagnosis a challenge. We present a case of a white retinal tumor in a 42-year-old woman that progressed slowly over 3 years and on enucleation an undifferentiated tumor was found without a conclusive diagnosis. Molecular analysis identified RB1 pathogenic variant that confirmed retinoblastoma diagnosis in this discordant clinicopathologic presentation of the tumor.