Position-Dependent Lung Shadow Movement.

A 73-year-old male presented with an abnormal chest x-ray revealing ground-glass opacity (GGO) in the left lower lung field, accompanied by elevated KL-6, SP-D, and GM-CSF antibody levels, indicative of autoimmune pulmonary alveolar proteinosis (PAP). Initial bronchoalveolar lavage and transbronchial lung biopsy revealed only nonspecific findings. During a CT-guided needle aspiration biopsy (CT-NAB), real-time imaging showed that GGO gradually moved and shifted with positional changes. Although PAP is not fully confirmed yet due to a lack of pathological findings, this case highlights several clinical suggestions for patients with atypical lung shadows, including those with suspicion of PAP. Further, this is the first report of lung shadow mobility during CT-NAB, emphasising the need for further studies to elucidate the pathophysiology of lung shadows and improve diagnostic accuracy.