Definition: An accumulation of pleural fluid in the potential space
between parietal and visceral pleura.
= Increased pleural fluid formation.
= Decreased pleural fluid absorption.
= Both increased formation and decreased absorption.
. Increased pleural fluid formation:
-Increased interstitial fluid in the lung.
- Increased intra-vascular pressure in pleura.
- Increased permeability of the capillaries in the pleura.
- Decreased pleural pressure.
-Increased fluid in the peritoneal cavity.
- Disruption of the thoracic duct.
-Disruption of the blood vessel in the thorax.
. Decreased pleural fluid absorption:
-Obstruction of the lymphatic draining.
- Elevation of the systemic vascular pressure.
Focal pleural disease.
Focal pleural disease may be divided into localized
pleural thickening, pleural calcification, or pleural mass.
Localized pleural thickening is usually result from
peripheral parenchymal or pleural disease.
Pleural calcification is usually result from old
inflammatory disease versus asbestosis.
Focal pleural masses are usually benign neoplasms
such as lipoma and localized fibrous tumour.
The benign tumour appears as well defined, spherical
or oblong masses.
The pleural metastases are one of the vast majority of malignant
lesions of the pleura.
The adenocarcinoma histological type is the most likely to produce
metastasis in the pleura.
The most common primaries to result in pleural metastases
lung cancer - may account for up to 40% of pleural metastases .
breast carcinoma .
may account for ~20% of pleural metastases2
commonly gives a pleural effusion
lymphoma - may account ~ 10% of metastases .
Although pleural effusion is often the major component of
metastatic disease to the pleura, other findings include pleural
nodules or extensive pleural thickening similar to that of
Pleural metastases itself does not usually give radiological image,
so that the chest radiograph usually shows only the images of
The CT is the method of choice for the study of pleural metastasis.
CT may show nodules radiographically base hidden by pleural
effusion. The pleural metastases usually manifest as nodular or
lenticular masses. The soft tissue component is enhanced frequently
after administration of intravenous contrast. Other findings seen on
CT are enlarged mediastinal lymph nodes, lung nodules, rib lesions
or subcutaneous mass.