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Pleural Diseases
Anatomy of the Pleura (embryology)
•The Pleural cavity derivatives are derived
from splitting of the lateral mesoderm into
splanchnic and somatic layers.
•The paired cavities are separated by 3
partition into 3 subdivision: Pericardial, Pleural,
and Peritoneal cavity
•The three partition are: The Unpaired septum
transversum, the Paired pleuropericardial
folds, the Paired pleuroperitoneal folds
Anatomy of the Pleura (histology)
•Submesothelial layer contains collagen
tissue, elastic fiber, small blood vessels,
lymphatic network, nerve fiber. The cell in this
layer is fibroblast, negative of cytokeratin,
carcinoembryonic antigen, factor VIII-related
antigen.
•The parietal pleura has large dehiscence or
stomata, connecting the pleural cavity with
subpleural lymphatic network and permit
entrance of material into the lymphatics from
the pleural space
Anatomy of the Pleura (gross anatomy)
• The parietal pleura lines the chest wall,
mediastinum, diaphragm, and form the cupola
or pleura dome at the thoracic inlet bilaterally.
• The diaphragmatic pleura adheres tightly to
the diaphragm. The mediastinum pleura
adherent tightly to pericardium. The cupola,
costal pleura can dissected from the
underlying tissue.
• The pleura recesses, usually two, is visible at
chest PA i.e. the Azygoesophageal recess and
the Superior esophageal recess
Anatomy of the Pleura (Blood supply)
• Visceral pleura arterial supply is from the
bronchial and pulmonary arterial systems.
• The veinous drainage is to the Pulmonary
veins.
• The parietal pleura arterial supply is from
various systemic arterial supply of the chest
wall, diaphragm, and mediastinum.
• Veinous drainage is directly is to the superior
vena cava.
Anatomy of the Pleura (Lymphatics)
• The lymphatic drainage of the visceral is to the
pulmonary plexus located in the interlobar and
peribronchial space. A direct subplerual lymphatic
connection to mediastinal node is possible in 22-25%
of people.
• Lymphatic drainage of the parietal pleural is to the
parietal pleural lymphatic channels, the stomata and
around the Kampmeier’s foci.
The lymphatic network of the chest wall drain into
internal mammary chain anteriorly and intercostals
chain posteriorly.
The drainage of the diaphragmatic pleura is to
retrosternal and mediastinal and celiac lymph node
Anatomy of the Pleura (Nerve supply)
• Parietal pleura is innervated by both
somatic, sympathetic and parasympathetic
fiber via the intercostal nerve.
• The diaphragmatic pleura is supplied by
phrenic* nerve.
• The visceral pleura is devoid of any somatic
nerve supply.
Important points of note
• Under normal condition the pleura cavity and
spaces contains no free air.
•The virtual space between the parietal and
visceral pleura is under negative pressure in
relation to the surrounding outside air.
Laws of the pleura gas exchange
The rate of gas resorption in the pleural
spaces are depends on four laws:
1) Diffusion properties of the gas.
2) The pressure gradient for the gas in pleura
in relation to venous blood.
3) The area contact between pleura gas and
pleura.
4) Permeability of the pleural surface.
Ex: the oxygen is resorbed 62 times faster
than nitrogen, CO2 23 times more soluble than
O2. water and CO2 share the same
Pneumothorax
Is the collection of air or gas in the pleural
cavity of the chest between the lung and the
chest wall.
Clinical subtypes
• Spontaneous Pneumothorax (COPD > 70
%, emphysema & cystic fibrosis)
• Traumatic Pneumothorax (blunt injury)
• Tension Pneumothorax
3 potential situations may affect the resorptibility
of air causing a Pneumothorax
• Close rigid cavity: Non re-expandable lung.
• Closed collapsible cavity: Due to a negative
intrapleural pressure.
• Open cavity*: the communication between
the lungs, pleural cavity, and chest wall
(Bronchopleural fistula)
Pleural Effusion
Pleural Masses
• Benign: Lipomas, & pleural fibromas, and
rounded atelectasis.
• Malignant: Metastasis* (most common), other
less common causes Lymphoma, thymomas &
asbestos related Malignant mesothelioma
39-year old female with no significant past
medical history
Benign pleural fibroma
Usually found incidentally by chest radiography
• Common in 4th to 6th decade, +/- hx of asbestos
exposure, no gender distribution.
• Presenting symptoms (~50-60%
asymptomatic),others symptoms (dyspnea, chest
pain, hemoptysis).
• Most behave as slowly growing, painless masses.
Associated hypertrophic pulmonary osteoarthropathy
and episodic hypoglycaemia (due to production of
insulin-like growth factor) may be present in 4-5% of
cases.
• 80% arise from visceral pleura and 20% from
parietal pleura.
• Calcification present in ≤5%, central necrosis is
common in the larger tumors.
49-year old Pxt presented with no symptoms of
tightening chest pain.
At presentation
A few weeks later
Malignant pleural
mesothelioma
• Malignant pleural mesothelioma is tumor
that develops from the protective lining
covering the outer lining of the lungs and
internal chest wall due to exposure
to asbestos.
• CXR may show unilateral, concentric,
plaque like, or nodular pleural thickening.
• CT shows in detail involvement of
mediastinum and diaphragm and chest wall.
• MRI shows the plagues as hyperintense <
muscles on T2w.
70-year-old man patient admitted with chest
pains, dyspnea, and cough
Pleural lipoma
• Pleural lipomas are benign soft-tissue
neoplasms that originate from the
submesothelial layers of parietal pleura and
extend into the subpleural, pleural or
extrapleural space.
• Are soft, encapsulated fatty slow growing
tumors.
• CT may demonstrate fat attenuation
(approximately -100 HU) (3). If lesion is close
to diaphragm may be mistaken for a hernias
(Morgagni & Bochedalek)
66-year-old asymptomatic patient with a previous
history of having worked in the mine
Round Atelectasis
• Round atelectasis is an unusual form of lung
collapse adjacent to the pleural surface & may
simulate a pulmonary neoplasm
• Comet tail sign* is pathognomonic & occurs due to
distortion of vessels and bronchi that lead to an
adjacent area of round atelectasis. Bronchovascular
bundles appear to be pulled into the mass and
resemble a comet tai.
Comet tail sign may be appreciated on both CT and
conventional X ray images.
• Crow’s feet sign linear bands radiating from mass
into lung parenchyma.
• Linear densities radiate back toward hilum .
• Air bronchogram
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