title: Cutaneous tumefaction in empyema necessitatis.
abstract: BACKGROUND
  Empyema necessitatis refers to a collection of exudative fluid that extends directly from the pleural cavity to the thoracic wall to form a mass in the extrapleural soft tissue of the chest. It was an uncommon complication of tuberculous pleural effusion even in the pre-antibiotic era, and has also been associated with bacterial lung abscess, actinomycosis, blastomycosis, and malignancies.
  
  
  METHODS
  Seven instances of chest wall mass lesion secondary to empyema necessitatis, diagnosed by fine-needle aspiration biopsy (FNAB), are reported.
  
  
  RESULTS
  Three cases were tuberculous, two were mesotheliomatous, one was caused by pulmonary small cell carcinoma, and another was due to coexisting Actinomyces and Actinobacillus. In all patients, subsequent pleural fluid cytologies demonstrated empyema with the respective etiologies identified.
  
  
  CONCLUSIONS
  The usefulness of FNAB in the diagnosis of empyema necessitatis, supported by radiographic imaging and ancillary procedures, is well illustrated by these seven cases.
authors.affiliation: Cytology Section, Veterans Affairs Hospital, Hines, and Department of Pathology, Morris Hospital, Morris, IL, USA. creyes@morrishospital.org
authors.forename: Cesar V
authors.initials: CV
authors.lastname: Reyes
mesh_terms: D000189:Actinobacillus Infections / Q000150:complications; D000196:Actinomycosis / Q000150:complications; D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D001940:Breast / Q000473:pathology*; D018288:Carcinoma, Small Cell / Q000150:complications / Q000473:pathology; D016724:Empyema, Pleural / Q000000981:diagnostic imaging / Q000209:etiology / Q000382:microbiology / Q000473:pathology*; D004654:Empyema, Tuberculous / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology*; D017809:Fatal Outcome; D006801:Humans; D008175:Lung Neoplasms / Q000150:complications; D008297:Male; D008413:Mastitis / Q000209:etiology / Q000382:microbiology / Q000473:pathology*; D008654:Mesothelioma / Q000150:complications / Q000473:pathology; D008875:Middle Aged; D011859:Radiography; D013909:Thorax / Q000473:pathology*