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PH-RS23

Pleuritis, empyema and other pleural collections

How an inflamed pleura lays down fibrin, fluid or pus, why the pain is sharp and the rub creaks, how a pleural infection matures into a fibrous peel, what blood and chyle in the chest mean, and how pleural scars and asbestos plaques form.

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  • 5 steps · 9 questions
  • 3D anatomy, affected parts marked

By the end, you can

  • Relate the mesothelium, its nerve supply and its fibrin-dissolving lining to pleuritic pain and pleural healing.
  • Distinguish fibrinous, serofibrinous, purulent and tuberculous pleuritis by cause, exudate and outcome.
  • Explain how pleural infection passes through exudative, fibrinopurulent and organising stages, and why each stage changes the fluid.
  • Explain how blood and chyle reach the pleural space and how each collection is recognised.
  • Relate organisation to adhesions, fibrothorax and trapped lung, and distinguish these scars from asbestos plaques.
  • Recognise the classic appearances, fluid values and tests, and explain how drainage, fibrinolytics, antimicrobials and surgery act on the mechanism.

What it is

Pleuritis (pleurisy) is inflammation of the pleura. Its exudate may be mainly fibrin (dry or fibrinous pleuritis), fibrin with fluid (serofibrinous), pus (empyema) or, in tuberculosis, a lymphocyte-rich fluid with granulomas. Other material can fill the pleural space without much inflammation: blood (haemothorax) and chyle (chylothorax). Whatever is not removed is organised into fibrous adhesions or a peel; asbestos leaves separate scars, pleural plaques.

4 types to tell apart
Fibrinous and serofibrinous pleuritis
Fibrin on the pleural surfaces, with little (dry) or more (serofibrinous) protein-rich fluid; from pneumonia, viral infection, pulmonary infarction, autoimmune disease or uraemia.
Purulent pleuritis (empyema)
Pus in the pleural space, usually from bacterial pneumonia; it passes through exudative, fibrinopurulent and organising stages.
Tuberculous pleuritis
A hypersensitivity reaction to mycobacterial antigens: lymphocyte-rich fluid and caseating granulomas, with few bacilli.
Haemothorax and chylothorax
Blood (usually after trauma) or intestinal lymph (from a damaged or blocked thoracic duct) collecting in the pleural space.

US spelling: haemothorax → hemothorax, fibres → fibers.

Normal function

The pleura: a gliding, pain-sensitive serous lining

The is a serous membrane in two layers: the visceral pleura covers the lungs and dips into their fissures, and the parietal pleura lines the chest wall, the and the mediastinum. Both are covered by mesothelium, a single layer of flat cells with microvilli that keeps a slippery film of fluid between the layers, so they glide with every breath. Parietal capillaries make the fluid and parietal lymphatics drain it, as the pleural effusion lesson explains; the same lymphatic openings clear cells and particles.

Only the parietal pleura feels pain. Its costal part and the rim of the diaphragm are supplied by the intercostal nerves, so pain is felt sharply in the chest wall over the inflamed area, or in the upper abdomen from the lowest nerves. The central diaphragmatic and mediastinal parts are supplied by the phrenic nerves (C3–C5), so pain from there is referred to the shoulder tip. The visceral pleura has no pain fibres.

A healthy mesothelium dissolves the small amounts of fibrin that form on it, using plasminogen activators. Inflammation tips this balance towards fibrin building up. Like other serous membranes, the pleura then heals in one of two ways: resolution, when the exudate is dissolved and drained, or organisation, when it is turned into fibrous tissue. Which happens sets up most of this lesson.

Point to it on the model