Concordant Optic Glioma in a Pair of Monozygotic Twins with Neurofibromatosis

The occurence is reported of optic chiasma gliomas in a pair of identical twins, both with neurofibromatosis. One twin developed precocious puberty in the sixth year of life and was shown by cisternal computerized tomography to have a supersellar tumor, which proved to be a malignant glioma. The second twin had an abnormal growth spurt but not overt precocious puberty. Cisternal computerized tomography of the second twin revealed evidence of a similar, smaller tumor at the same site. The literature is reviewed and some possible genetic explanations discussed. This report also emphasises the importance of careful investigation of the second twin when a malignancy is found in one, irrespective of the site or type of the tumor.