There are TONS of causes of leukocoria (white pupil).  But this can be a very important differential, as it can be the presenting sign of some sight-threatening and life-threatening conditions (most obviously retinoblastoma).  Because of its clinical importance, it is essential to be able to not only recognize what it is, but to also have a decent differential diagnosis so that you don’t miss out on any key causes when conducting a history and physical.