Introduction: Recognizing the symptoms of vincristine-induced peripheral neuropathy (VIPN) earlier is crucial to preventing the persistent neurological sequelae. The treatment of neuropathy is to discontinue the drug, and the effect of a missed dose of vincristine on treatment success is unclear. This study aims to evaluate VIPN in children with malignancy and the effect of skipping vincristine doses on the treatment success of patients at a single center, retrospectively. Methods: Medical records of the children with cancer who received vincristine in our institution between 2013 and 2020 were analyzed retrospectively. Results: Vincristine neuropathy was found in 42 (7%) of 598 pediatric patients who received at least one dose of vincristine during the study period. Neuropathy developed at a statistically significantly lower cumulative dose in patients younger than seven years of age (p=0.04). The mean neuropathy duration of the cases was 8.5 months, and the findings of 40 (95.2%) cases improved. The mean cumulative dose was higher in patients with diffuse nerve involvement. The missed dose of vincristine was lower in the cases in complete remission compared to the other cases and higher doses of vincristine were missed in the stable disease group than in the remission group (p=0.03). Conclusion: VIPN can be encountered in less cumulative doses, mainly in the younger age group. Missed doses of vincristine may affect treatment success, and more comprehensive studies are needed to show this effect more clearly.

Objective: Neurofibromatosis type 1 (NF1) is the most common hereditary neurocutaneous syndrome. The most crucial morbidity of NF1 is tumors that may develop. Cases with café-au-lait macules (CALMs) which is the first clinical finding of NF1, due to the anxiety of its associated morbidity, are referred to the pediatric oncology clinic. In this study, we aimed to examine the characteristics of the patients who applied to our outpatient clinic with CALMs. Patients and Methods: The data of 157 pediatric patients who applied to our institution with the diagnosis of CALMs between June 2010 and November 2020 were analyzed retrospectively. Results: There were 157 pediatric cases referred to us for CALMs. According to the National Institutes of Health (NIH) diagnostic criteria, 109 (69.4%) cases were diagnosed with NF1. The diagnosis of 22 cases with NF1 were supported by genetic examination. Optic glioma was detected in 39 (24.8%) cases. In 15 (38.4%) of cases with optic glioma, visual functions were also affected. Second diagnostic criterion did not develop during the follow-up period, except for macules, in 48 cases (30.5%). Conclusion: In cases with multiple CALMs, the probability of NF1 diagnosis is high, and close and regular follow-up is of great importance in catching the development of the second clinical criterion and minimizing its morbidity.