The frontal chest x-ray shows a left sided pleural based opacity bulging into the lung field. The shape of the opacity is lenticular or reverse D. In a patient with symptoms & signs of sepsis, this should heighten suspicion for an empyema.

The patient had a CT scan subsequently which showed a large complex loculated left pleural effusion. Pleural fluid analysis was consistent with empyema.

Simple pleural effusion causes a meniscus sign. If D or lenticular shaped opacity is noted on a chest x-ray, consider empyema as one of the differentials.