Retrospective investigation of clinical features of patients diagnosed with neurofibromatosis type 1

Objective: To retrospectively evaluate the demografic, clinical, laboratory findings and treatments of patients registered with the diagnosis of Neurofibromatosis type 1 (NF1) in pediatric oncology outpatient clinic and to investigate the relationship between these parameters and NF1 findings. Method: In our study, 76 patients aged 0-18 years who were diagnosed with NF1 between January 2007 and September 2022 in the Department of Pediatric Oncology, Manisa Celal Bayar University Hospital were included. Demografic data, anthropometric measurements, neurological examination findings, clinical features and imaging findings of the patients were obtained from database records and file information. Results: 44.7% of the patients were female, 55.3% were male, mean age was 11.35±5.41 years, median age was 12 years. The mean follow-up period was 6.1 years±4.1 years. The diagnosis was made in the first decade of life in 80.3% of the patients. 48.7 % had a family history and 15.8% had consanguinity. Among the diagnostic criteria, cafe au lait macula was found in 98.7%, axillary-inguinal freckling in 51.3%, cutaneous/subcutaneous neurofibroma in 22.4%, plexiform neurofibroma in 17.1%, Lisch nodüle in 30.3%, optic tract glioma in 9.2%, skeletal dysplasia in 30.3%. The first complaint at presentation to the hospital was cafe au lait macula in 82.9%. The number of people who presented to the hospital because of having a family member with a diagnosis of NF1 was 5 (6.6%), 3 (4%) because of convulsion and 3 (4%) neurofibroma-plexiform neurofibroma. Mutation was detected in 48.7% of the patients. On cranial MR imaging, T2-hyperintensity lesions were observed in 73.7%. The most common FASI was 53,9% in the cerebellum, 46.1 % in the basal ganglia, 23.7% in the cerebrum, 19.7% in the thalamus, 18.4% in the mesencephalon, 17.1% in the capsula interna, 15.8% in the pons, 6.6% in the hippocampus and 3.9% in the corpus callosum. When the relationship between FASI involvement sites and school achievement was analysed, it was noted that patients with basal ganglion involvement had lower school achievement. When the presence of neurofibroma was compared with the sites of FASI involvement, the rate of neurofibroma was higher in patients with FASI involvement in the corpus callosum or cerebellum. The incidence of Lisch nodules was also significantly higher in patients with FASI lesions in the capsula interna. Of the 34 patients whose measurements were recorded, 25.8% had a height below -2 SDS. One patint was being followed up because of puberty precox and two patients were being followed up because hypothyroidism. Both patients with hypothyroidism had NF1 mutation. Conclusion: A good knowledge of the clinical features of NF1 disease will enable patients to be diagnosed early, families to be informed, genetic counselling to be provided and follow-up to be planned. The risk of malignancy is increased compared to the general population and patients should be followed up regularly because of the risk of associated complications. NF1 has a large gene family, therefore it is important to explain the pathogenesis and course and to develop treatment methods. More studies are needed fort his purpose. Keywords: Neurofibromatosis, T2-hyperintens lesions, FASI