Empyema differential diagnosis

	Empyema Microchapters
Patient Information
Overview
Classification Subdural empyema Pleural empyema
Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Empyema must be diffrentiated from pneumonia, lung abscess, lung cancer and parapneumonic effusions as shown below:

Variable	Empyema Thoracis	Lung abscess	parapneumonic effusion	Pneumonia	Lung cancer
Presentation	Variable presentation but may follow long standing pneumonia	Usually has history of aspiration pneumonia, alcoholics, drug abusers, seizure disorder, have undergone recent general anesthesia, or have a nasogastric or endotracheal tube.	Usually follows pneumonia	presents with fever, pleuritc chest pain, cough	mostly asymptomatic but may have cough productive with hemoptysis
Causes
Laboratory findings

CXR			A homogenous opacification is noted at the affected side. The costophrenic angle is obliterated with a meniscus.
Chest ultrasound	Ultrasound in empyema is positive for suspended microbubble sign, air fluid level, curtains sign and loss of gliding sign.^[1]	Ultrasound in lung abscess is negative for suspended microbubble sign, curtains sign and loss of gliding sign but air fluid level may be seen,.^[2]
CT scan	Seen as a lung mass whose cavity is regular with smooth and regular lumen, well-defined defined boundary and shape changes with change in patient's position.^[3] Mass may resolve on antibiotics The split pleura sign is present (most reliable sign to differentiate empyema from lung abscess)	Lung mass whose cavity is rregular with undulated lumen, irregular-poorly defined boundary and shape does not change with change in patient's position.^[4] Mass may resolve on antibiotics			Seen as a lung mass that does not resolve on antibiotics