Spontaneous regression of retinoblastoma in identical twins.

Spontaneous regression of retinoblastoma is described in identical twin boys. In the one bilaterally affected child 2 tumours regressed spontaneously, while a third lesion, which developed at a later stage, required treatment in the form of a cobalt plaque. The second child showed spontaneous regression of the single tumour in his only affected eye. The pathogenesis of spontaneous regression is-discussed and a possible common aetiology in these 2 cases postulated.