The authors present the case of 12-year-old girl who is followed since the age of 9 months for m. Recklinghausen. One year before admission to hospital she developed sciatic pain. She underwent several examinations and MRI evaluation of the spine and the skull in neurological out-patients wards with negative findings. In our department we diagnosed a tumour of the sciatic nerve near of foramen infrapiriforme by palpation and confirmed then by MRI and ultrasound. After successful removal of the neurofibroma she has no problems. She is followed by ultrasound and MRI. The authors stress the importance of precise clinical evaluation and the importance of graphic methods which can confirm our clinical suspicion, and are also able to detect recurrences.

        Key words: peripheral nerve tumours, sciatic nerve, neurofibroma, sonographic and MRI evaluation, surgical therapy