Pleura & peritoneum
Pleura nonneoplastic conditions
Pleural effusion
Author: Vaidehi Avadhani, M.D.
Last author update: 1 December 2013
Last staff update: 2 September 2020
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Pleural effusion[TI] pathology free full text[sb]
Table of Contents
Definition / generalCite this page: Avadhani V. Pleural effusion. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pleurapleuraleffusion.html. Accessed June 7th, 2023.
Definition / general
- 15 cc or more of fluid within pleural cavities
- Most common causes are congestive heart failure and metastatic disease
- Due to increased hydrostatic pressure (congestive heart failure), increased vascular permeability (pneumonia), decreased oncotic pressure (nephrotic syndrome), increased intrapleural negative pressure (atalectasis), decreased lymphatic drainage (carcinomatosis)
- May or may not be inflammatory
- Malignant effusions are usually greater than 500 ml; are often first evidence of malignancy
- For lung, breast and ovarian metastases, 92% of pleural effusions are ipsilateral to primary lesion
Inflammatory pleural effusion:
- Either serous, serofibrinous or fibrinous
- Due to inflammation in lung (tuberculosis, pneumonia, infarct, abscess, bronchiectasis), collagen vascular disease (rheumatoid arthritis, systemic lupus erythematosis, uremia) or radiation therapy
- Empyema: pus in pleural cavity; due to bacteria or fungal seeding of pleural space; often from lung infection; usually organizes into dense adhesions but does not disappear
Noninflammatory pleural effusion:
- Hydrothorax: clear / straw colored fluid; usually due to congestive heart failure
- Isolated right sided hydrothorax seen in Meigs syndrome (hydrothorax, ascites, ovarian fibroma)
- Usually is NOT loculated, collects basally
- Hemothorax: usually due to rupture of aneurysm or vascular trauma; associated with large clots
- Chylothorax: accumulation of milky white fluid, usually lymph, contains fat (DD: turbid serous fluid); usually left sided, caused by thoracic duct trauma / obstruction due to malignancy
