A clonal translocation t(10;21) in an optic glioma of a patient with neurofibromatosis type 1 (NF 1).

An 11-year-old boy affected by neurofibromatosis type 1 is presented with severely impaired vision on the right eye (0.1). MRI demonstrated a 2.3 x 1.8 cm tumour of the optic chiasma. After open biopsy cytogenetic analysis was performed on primary cultures of this optic glioma (grade I). A clonal translocation t(10;21)(q21.2;21.1) was detected in 66% of the metaphases analysed. The boy received fractioned irradiation with a total tumour dose of 60 Gy. The ultimate MRI taken 18 months after radiotherapy showed no residual tumour. The vision on the right improved to 0.2, but decreased on the left to 0.6. The patient attends high school with no impairment in his daily life.