We report the case of a 15-year-old Caucasian male presenting with unclear fever, relapsing otitides, and facial and nasal ulcerations for the first time in March 2020. Nasal biopsies showed extensive necrotizing granulomatous inflammation. cANCA/PR3 antibodies were highly elevated (360 U/ml, upper reference limit 20 U/ml). Imaging [sonography and magnetic resonance imaging (MRI)] revealed splenic infarction due to arteritis lienalis. There were no signs of kidney, lung, joint, or central nervous system involvement. The patient met the 2017 American College of Rheumatology criteria (ACR) for GPA. He was treated with high-dose steroids (1 g/day over 3 days), followed by azathioprine (2 mg/kg/day) and low-dose steroids as maintenance treatment. Owing to the splenic infarction caused by vasculitis of the splenic artery, he also received prophylactic antibiotic (penicillin) and anticoagulatory treatment (salicylic acid). The patient initially responded very well to the immunosuppressive treatment, and levels of PR3 antibodies normalized until May 2020. Consequently, glucocorticoids, salicylic acid, and penicillin could be discontinued. However, after discontinuation of steroid treatment, we detected another increase of PR3 antibodies up to 128 U/ml in June 2020, but owing to the good clinical apparition no further action was taken and levels of autoantibodies tended to decrease spontaneously. In September 2020, he was admitted with a 2-week history of shortness of breath, even without physical activity, and inspiratory stridor. Moreover, he complained about hearing loss after discontinuation of glucocorticoid treatment. Lung function testing showed severe obstruction of the upper airways [forced expiratory volume in 1 s (FEV1) 50% of age norm] and a massively increased airway resistance [effective airway resistance (sReff) 1018% of age norm]. MRI revealed a circular subglottic tracheal narrowing over a length of 2 cm. The levels of the beforehand-elevated PR3 antibodies showed no further increase (93 U/ml). We initiated a high-dose steroid treatment for 3 days followed by four subsequent doses of rituximab (RTX, 375 mg/m2, cumulative dose: 4 × 700 mg) in 4-week intervals for remission induction according to the therapy protocol of the RAVE study []. Clinical apparition and lung function parameters clearly improved under therapy, but the patient still reported shortness of breath under heavy physical activity and the flow profile in the body plethysmography still showed signs of tracheal stenosis. To match the decreasing dosages of oral glucocorticoids, he received inhalative corticosteroids (ICS; budesonide) together with a slow-acting bronchodilator (formoterol) in addition to the ongoing maintenance therapy with AZA on the occasion of a routine appointment in our pediatric pneumology department in November 2020. At that time, levels of PR3 antibodies also reached the normal range. After 3 months, in February 2021, his obstructive respiratory symptoms worsened as he complained about increasing inspiratory stridor. Blood gas analysis revealed a mild CO2 retention, and his lung function parameters showed a deterioration to similar values as in September 2020 (FEV1 55% of age norm, sReff 1039% of age norm). Again, we performed an MRI, which showed a circular subglottic tracheal narrowing over a length of 1.5 cm. To exclude further affection of the lower airways, we performed a chest computed tomography (CT) scan. Direct laryngoscopy showed a Cotton–Myer grade III subglottic stenosis, beginning 1 cm below the vocal cords with a length of 1.5 cm. A biopsy taken from the subglottic tracheal lesion revealed ongoing neutrophilic inflammation. Again, high-dose steroids were initiated, but, in contrast to the prior admission in September 2020, the patient responded poorly. After consideration of the increased risk of infection due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic and the persistently low B-cell count after the first RTX treatment, we decided against a second RTX cycle or other therapeutic alternatives (for example, cyclophosphamide) and initiated a TNF-α-antagonistic treatment with infliximab with a starting dose of 6 mg/kg. In induction phase, he received the first three doses in 2-week intervals, followed by 4-week intervals in maintenance phase. Moreover, AZA dosage was adapted to body weight. Our patient responded very well to the TNF-α-antagonistic treatment as his respiratory symptoms resolved completely and his lung function parameters normalized entirely (FEV1 92% of age norm, sReff 361% of age norm; Fig. ). At his last appointment in May 2021, he was in complete clinical remission.