Empyema classification

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

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Prince Tano Djan, BSc, MBChB [2]

Overview

Empyema may be classified according to the etiology, anatomical location, and pathological course of the disease. Primary empyema occurs most commonly as iatrogenic empyema without associated pneumonia whereas secondary empyema happens more commonly secondary to pneumonia. Empyema necessitans is a spontaneous discharge of an empyema that has burrowed through the parietal pleura into the chest wall to form a subcutaneous abscess that may eventually rupture through the skin. On the basis of etiology empyema is mostly caused by bacteria. It may be tuberculous or nontuberculous. Tuberculous empyema is the most common cause of empyema necessitans with majority of affected patients being immunocompromised. There are 3 stages of empyema which are important in terms of the laboratory findings. These are exudative, fibrinopurulent and organizing.

Classification

Empyema may be classified according to the etiology, anatomical location/organ, and pathological course of the disease as follows:

Primary vs secondary empyema

Primary empyema occurs most commonly as iatrogenic empyema without associated pneumonia whereas secondary empyema happens more commonly secondary to pneumonia.

Empyema necessitans

Empyema necessitans is a spontaneous discharge of an empyema that has burrowed through the parietal pleura into the chest wall to form a subcutaneous abscess that may eventually rupture through the skin.

Tuberculous vs nontuberculous empyema

Tuberculous empyema is the most common cause of empyema necessitans. This disease can be found in patients with impaired immunity or who are immunocompetent howvever majority of patients affected are immunocompromised.

Gallbladder empyema

This is also called suppurative cholecystitis which may complicate acute/chronic cholecystitis whereby pus collects in the gall bladder lumen. It is common in people with diabetes and atherosclerotic disease.

Normally results from an obstruction of the cystic duct hampering drainage of bile from the gall bladder which becomes secondarily infected.

Stages of empyema

Empyema may be classified according to the stage of the disease as follows:

• Exudative

In the exudative stage, the pus accumulates, and initial sterile fluid becomes infected with fluid characteristics of;

• • glucose>60
  • pH>7.2
  • LDH<500

• Fibrinopurulent

During this stage, bacterial multiplies with increase in polymorphs and fibrin deposition on both pleural surfaces with fluid characteristics of;

• • glucose<40
  • pH <7.2
  • LDH>1000

• Organizing

This stage is characterized by loculations, inelastic membranous peel, and lung entrapment as a result of scarring of the pleural space.