[Complete left lung atelectasis as the initial presentation of allergic bronchopulmonary aspergillosis: a case report].

This paper reports a case of allergic bronchopulmonary aspergillosis (ABPA) presenting with acute respiratory failure and complete left lung atelectasis on imaging. The patient had no prior history of respiratory disease and experienced a sudden onset of symptoms, with partial atelectasis of the left lung rapidly progressing to complete collapse. Significant clinical improvement was observed after bronchoscopic removal of a suspected "foreign body" from the left main bronchus, leading to an initial misdiagnosis of bronchial foreign body. However, one month later, follow-up imaging revealed a new shadow in the left upper lobe. Further investigation confirmed the diagnosis of ABPA caused by sensitization to Aspergillus terreus.The patient was treated with two courses of systemic corticosteroids combined with antifungal therapy, resulting in effective disease control. Over a six-year follow-up period, the patient maintained a favorable prognosis with no progression to late-stage pulmonary complications. Complete lung atelectasis-type ABPA poses significant diagnostic challenges in its early stages and remains rarely reported in the domestic literature, leading to a high risk of misdiagnosis or delayed diagnosis. This case report aims to raise clinical awareness and facilitate earlier recognition of this uncommon presentation among healthcare professionals.