Empyema
An empyema () is a collection or gathering of pus within a naturally existing anatomical cavity. For example, pleural empyema is empyema of the pleural cavity. It must be differentiated from an abscess, which is a collection of pus in a newly formed cavity. The term is from Greek ἐμπύημα, "abscess".

Classification
Empyema occurs in:

the pleural cavity (pleural empyema also known as pyothorax)
the thoracic cavity
the uterus (pyometra)
the appendix (appendicitis)
the meninges (subdural empyema)
the joints (septic arthritis)
the gallbladder

External links

Shen, K. Robert; Bribriesco, Alejandro; Crabtree, Traves; Denlinger, Chad; Eby, Joshua; Eiken, Patrick; Jones, David R.; Keshavjee, Shaf; Maldonado, Fabien; Paul, Subroto; Kozower, Benjamin (February 2017). "The American Association for Thoracic Surgery consensus guidelines for the management of empyema". The Journal of Thoracic and Cardiovascular Surgery. 153 (6): e129–e146. doi:10.1016/j.jtcvs.2017.01.030. PMID 28274565.