The frontal chest x-ray shows a triangular density in the right upper zone with a displaced horizontal fissure consistent with a right upper lobe collapse. There is also silhouetting of the left hemi-diaphragm, indicating the presence of left lower lobe consolidation.

In this case, the patient had a mucus plugging in the right upper lobe bronchus which led to the collapsed upper lobe.

Right upper lobe collapse can be caused by mucus plugging, secretions, foreign body, or a bronchogenic carcinoma.