The chest x-ray shows

left pleural based opacity protruding into the lung field with a reverse D appearance. in a patient with symptoms and signs of sepsis, this should raise suspicion for an empyema. CT scan confirmed the presence of a loculated left pleural effusion with split pleura sign.

Teaching point –

1. A simple pleural effusion causes a meniscus sign on chest x-ray (concave upper border).
2. Consider empyema if a reverse D opacity is seen on chest x-ray in a patient with sepsis.