title: CT demonstration of empyema necessitatis.
abstract: Empyema necessitatis is a collection of fluid that has, by direct extension from the pleural cavity, penetrated the thoracic wall to form a mass in the extrapleural soft tissues of the chest wall. This is a rare condition and usually is associated with tuberculous effusion but may be associated with malignancy, blastomycosis, actinomycosis, and may even follow thoracentesis.
mesh_terms: D000368:Aged; D004654:Empyema, Tuberculous / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D010996:Pleural Effusion / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D014396:Tuberculosis, Pleural / Q000000981:diagnostic imaging*