A woman in her early 20s with previously well-controlled intermittent asthma presented with sudden-onset dyspnoea and wheeze, initially treated as a life-threatening asthma exacerbation. Despite optimal medical therapy, her condition deteriorated, and imaging revealed a large anterior mediastinal mass causing tracheal compression. Biopsy confirmed nodular sclerosing classical Hodgkin lymphoma. This case highlights the importance of early imaging and maintaining a broad differential when patients do not respond to standard asthma therapy.