A 25 year old woman was referred to our center for further evaluation of an exercise-induced dyspnea. Moreover, the patient suffered from hoarseness and recurrent sinusitis and otitis. After initially finding nothing suspicious, a spiro-ergometry was performed. Interestingly, we saw a relevant limitation of the inspiratory flow-volume curve under maximal exercise load. Further evaluation (in particular the bronchoscopy and the resulting biopsies) led us to the final diagnosis of a granulomatosis with polyangiitis. After 4 weeks of an established therapy regime with prednisone and rituximab the prior detected subglottic stenosis and the inspiratory flow-volume curve limitation could no longer detected. We describe a rare differential diagnosis of an exercise-induced asthma and we underline the importance of a multimodal therapy concept. We highlight the critical nature of the flow-volume curve in spiro-ergometry under maximal exercise load. We recommend frequent follow-up control visits to monitor the subglottic stenosis.