Background: Methotrexate is the most commonly used disease-modifying antirheumatic drug recommended in the treatment of juvenile idiopathic arthritis. It can be administered orally or subcutaneously, the latter method is associated with fewer side effects and higher drug bioavailability. Nevertheless, the pain associated with injection is a considerable drawback of this treatment option in the pediatric population. Currently, there are two single-use subcutaneous injection devices available: the prefilled syringe and the prefilled pen. This prospective, two-sequence crossover study aimed to compare ease of use, frequency of therapy side effects, injection-site pain and parent/patient preference of those methotrexate parenteral delivery systems. Methods: Twenty-three patients with juvenile idiopathic arthritis, already treated with subcutaneous methotrexate in the form of prefilled syringe in the period October 2018 – April 2019 completed a questionnaire evaluating their experience with this device. Subsequently, children received a one-month supply of pen autoinjector and completed the same questionnaire, regarding their experience with the new methotrexate delivery system. If the patient was not performing the injections himself the questionnaires were completed by the caregiver administrating MTX. The results obtained in both questionnaires were compared using the Wilcoxon matched-pairs signed-rank test. Results: 82,6% patients and their caregivers voted for the prefilled pen as their preferred method of subcutaneous methotrexate administration. Moreover, the injection with the prefilled pen was reported as less painful in comparison to the prefilled syringe (p < 0.01). Side effects of methotrexate were less pronounced after the prefilled pen treatment, this difference was most prominent regarding gastrointestinal adverse events associated with the injection (p < 0.01). Conclusion: Administration of methotrexate using the pen device is a promising way of subcutaneous methotrexate delivery in children with juvenile idiopathic arthritis, as the injection is less painful and associated with fewer side effects.

Diffuse fasciitis with eosinophilia (EF) is a rare condition classified as a part of the connective tissue disorders. The clinical presentation of this condition can be diverse, however the main symptoms include symmetrical swelling and hardening of distal parts of limbs accompanied by peripheral eosinophilia. The diagnostic criteria are not specified. In inconclusions cases Magnetic Resonance Imaging (MRI) and skin to muscle biopsy may be useful. The pathogenesis and ethiology remain unknown, but extensive physical exertion, certain infectious factors, such as Borrelia burgdorferi, or medications may serve as a trigger. EF affects equally women and men, mainly in their middle age, however the disease can occur at any age. The standard therapy contents gluccocorticosteroids. As a second-line treatment, methotrexate is usually chosen. In this article we compare world reports of EF in paediatric patients with the cases of two adolescent male patients recently hospitalized in the Department of Paediatric Rheumatology.