Pleuritis

Pleuritis or Pleurisy

Definition : Inflammation of the pleura ( covering of the lungs) called pleuritis or pleurisy.

Classification :

1. Serous, Fibrinous and Serofibrinous Pleuritis
2. Suppurative Pleuritis (Empyema Thoracis)
3. Haemorrhagic Pleuritis

1. Serous, Fibrinous and Serofibrinous Pleuritis : Acute inflammatin of the pleural sac (acute pleuritis) can results in serous, serofibrinous and fibrinous exudate.

Causes : 

INFECTIOUS CAUSE :

i. Tuberculosis

ii. Pneumonias

iii. Pulmonary infarcts

iv. Lung abscess

v. Bronchiectasis

OTHER CAUSES :

i. Collagen diseases - rheumatoid arthritis and disseminated lupus erythematous.

ii. Uraemia ( increase level of urea in blood)

iii. Diffuse systemic infections - typhoid fever, tularaemia, blastomycosis and coccidioidomycosis.

iv. Irradiation of lung tumours

Clinical Features : 

i. Chest pain on breathing

ii. Friction rub is audible on auscultation

iii. After resolution, exudate become reabsorbed or minimized

Complications : Repeated attacks of pleurisy may leads fibrous adhesions and oblitreration of the pleural cavity.

2. Suppurative Pleuritis ( Empyema Thoracis) : Serofibrinous effusion converts into purulent exudate due to bacterial or mycotic infections called suppurative pleuritis or empyema thoracis.

Causes : 

i. Direct spread of pyogenic infection from the lungs ( most common cause)

ii. Direct extension from subdiaphragmatic abscess or liver abscess.

iii. Penetrating injuries to the chest wall.

iv. Haematogenous or lymphatic routes (occasionally)

On Examination : 
i. In empyema, the exudate is yellow green, creamy pus that accumulates in large quantity.
ii. Empyema is finally replaced by granulation tissue and fibrous tissue.

Complications : 
i. When tough fibrocollagenic adhesions develop which obliterate the cavity.
ii. In later stage calcification may occur.
iii. Finally develop serious respiratory difficulty due inadequate pulmonary expansion.

3. Haemorrhagic Pleuritis : It is different from haemothorax because it have inflammatory cells or exfoliated tumour cells in the exudate.

Causes : 
i. Metastatic involvement of the pleura.
ii. Bleeding disorders.
iii. Rickettsial diseases - spotted fever, typhus fever rickettsioses, scrub typhus, anaplasmosis and ehrlichioses.

Source : Textbook of pathology (Harsh Mohan) 7th edition