[Rapidly Progressive Organizing Pneumonia Associated with Nontuberculous Mycobacterial Infection: A Diagnostic Challenge].

This case report describes a patient with rapidly progressive organizing pneumonia accompanied by cavitary lesions, in whom concomitant nontuberculous mycobacterial (NTM) infection caused significant diagnostic difficulty. Initial imaging showed rapidly worsening pulmonary consolidation and nodules with cavitation, raising concerns for pneumonia, tuberculosis, fungal infection, or vasculitis. However, surgical wedge resection confirmed the diagnosis of organizing pneumonia, and bronchoalveolar lavage cultures subsequently yielded NTM. This case highlights that NTM-associated organizing pneumonia with cavitary lesions can closely mimic other infectious diseases as well as vasculitic disorders presenting with an organizing pneumonia pattern on imaging, leading to substantial diagnostic challenges.