MRI and clinical differences between optic pathway tumours in children with and without neurofibromatosis

The purpose of this study was to evaluate the value of MRI in studying opti c pathway tumours associated with neurofibromatosis, and to look for potent ially helpful criteria for the management of such lesions. This retrospecti ve study included 14 children with neurofibromatosis type 1 (NF-1) as well as a lesion of the optic pathway. Clinical data and MRI findings were analy sed with regard to location, structure and course of the tumours, and were compared with 13 optic pathway tumours in patients without NF-1. The median age of onset was 4.1 years. 11 patients with NF-1 were asymptomatic. In th e NF-1 group, the optic nerves were involved in 10 cases without a cystic c omponent at the time of diagnosis. In the non-NF-1 group, the tumour was lo cated in the chiasma in 11 cases; 12 cases had a cystic component. 10 of th e NF-1 group had no tumour progression over an average follow-up of 3.2 yea rs without treatment. These findings suggest that optic astrocytomas in ass ociation with NF-1 are distinct lesions from isolated optic gliomas. In NF- 1, most such tumours show only slight progression, and may correspond to pe rineural gliomatosis rather than a true pilocytic astrocytoma. Among NF-1 p atients, initial MRI provides no prognostic criteria in children who subseq uently show tumour progression. Nevertheless, MRI can be useful in establis hing the diagnosis of NF-1 and can serve as a baseline study.