Significance of retinoma and phthisis bulbi for retinoblastoma.

Genetic counseling of retinoblastoma (RB) patients and their families is difficult and inaccurate. The data in this paper show that two ocular lesions, retinoma and phthisis bulbi, are associated with RB and can be useful in diagnosis and counseling. Phthisis bulbi is the end result of many conditions and can only be linked to RB if other evidence is present. Retinomas, on the other hand, have three distinctive clinical characteristics (irregular translucent retinal mass, calcification, and pigment epithelial disturbance) and quite accurately predict the presence of the RB gene. Recognition of the significance of retinoma and phthisis bulbi with respect to the RB gene is critical in genetic counseling. Of 34 individuals studied, 32 with retinoma and five with phthisis bulbi, two thirds had a family history of RB or RB in the other eye, and 23/37 of their offspring developed RB. The clinical course of RB in the six children known to be at risk on the basis of detection of the gene in the parent was significantly better than in 17 children that were symptomatic at the time of diagnosis.