Pathology of pleura &
laboratory investigations in
lung diseases
DR.USHA
Pleural fluid
Normally 10-15ml of pleural fluid is
present in the pleural cavity.
 Pleural fluid is produced by pairetal &
visceral layers.
 Most of the fluid is removed by the
lymphatics, remaining fluid lubricates
the lung & chest wall.

Pleural effusion
Is the accumulation of excess fluid in
the pleural cavity.
 Important manifestation
 Normally, no more than 15ml of serous
fluid present. This fluid is acellular, clear
fluid that lubricates the surface.

Etiology of pleural effusion
1.
2.
3.
4.
Increased hydrostatic pressure, as in
congestive cardiac failure.
Increased vascular permeability, as in
Pneumonias.
Decreased osmotic pressure, as in
Nephrotic syndrome.
Decreased lymphatic drainage, as in
Mediastinal carcinomatosis.
Clinical features


Pleuritic chest pain- increases on
inspiration, coughing, sneezing
Dyspnea
Clinical features

1.
2.
3.
4.
5.
500ml of fluid should be present to produce
the signs
Bulging of intercostal spaces on the affected
side
Diminished mobility of chest wall
Shift of mediastinum to the opposite side
Stony dullness on percussion
Bronchial breath sounds on auscultation.
Types of pleural effusion
Trasudate
 -Congestive cardiac
failure
 -Cirrhosis of liver
 -Nephrotic syndrome
Exudate
 -Pneumonias
 -Tuberculosis
 -Pulmonary
embolism
 -Malignancy
Types of pleural effusion based
on etiology
Non-inflammatory effusion
 Inflammatory effusion

Non inflammatory effusion
1.
2.
3.
Hydrothorax
Haemothorax
Chylothorax
Hydrothorax
Accumulation of serous fluid
 Unilateral or bilateral depending on the
cause.
 Causes- Congestive cardiac failure

Nephrotic syndrome

Cirrhosis of liver

Primary & Secondary tumors

Nature of Hydrothorax
Is a transudate
 Clear, straw colored
 Protein content less
 Very few cells.

Haemothorax
Accumulation of blood
 Causes-Trauma to the chest wall
-Ruptured aortic aneurysm

Chylothorax

Accumulation of milky fluid of lymphatic
origin
Causes of chylothorax
Thoracic duct trauma
 Obstruction to the thoracic duct by
secondary malignancy
 Filariasis

Inflammatory effusions

1.
2.
3.
Exudate type
Serofibrinous
Suppurative/Empyema thoracis
Haemorrhagic
Serofibrinous type
Causes-Pneumonias, Lung abscess,
Bronchectasis,
-Tuberculosis
-Rare causes-Rheumatoid arthritis, SLE,
Radiation injury.

Purulent/Empyema type
Accumulation of pus
Causes-direct spread of pyogenic infection from
lung
-direct extension of sub diaphragmatic
abscess or liver abscess
-Septicemia
Hemorrhagic effusion
-usually seen in primary or secondary
malignancies of pleura.
Investigations
1.
2.
3.
4.
5.
CBC
Sputum examination-gram’s, ZN,
Cytology
X-Ray- Homogeneous opacity(150ml)
CT, MRI- 50ml
Pleural tap- for pleural fluid
examination
Pleural fluid examination
Lymphocytic predominance-tuberculosis,
fungal infections, carcinoma
Polymorphic predominence-acute
bacterial infections
Presence of pleomorphic cellsmalignancy
Sequelae of pleural effusion
Permanent collapse of the lung
(Compression atelactesis)
 Pleural thickening, Adhesions
 Empyema

Pneumothorax

Accumulation of air in the pleural
cavity.
Causes of pneumothorax
1.
Spontaneous:
Emphysema,Bronchial asthma,
Tuberculosis.
2. Traumatic:
Perforating injury to the chest wall
3.Therapeutic:
Was once used in treatment of
tuberculosis
Types of pneumothorax
1.
2.
3.
Closed type- the opening is very small &
heals spontaneously
Open type- the opening is large & remains
patent
Tension- the opening is valvular(air enters
the pleural space during inspiration but
cannot escape during expiration so that a
positive pressure occurs in the pleural
cavity.
Clinical features
Pleuritic chest pain
 Dyspnea
 Collapse
 Crack pot sound on percussion
 Hyper-resonent sound on auscultation

X-ray

Hyper-translucent
Clinical significance of
Pneumothorax
1.
2.
Compression of pleura on lung may
lead to Atelactasis & leading to
Respiratory distress.
Tension pneumothorax- results if the
defect acts as ball valve permitting
entry of air & preventing escape of air.
Pleural tumors
1.
2.
3.
PrimaryBenign mesothelioma, malignant
mesothelioma
secondary
Solitary fibrous tumor
Very rare
 Benign tumor
 Not related Asbestos exposure.

Malignant mesothelioma
Etiopathogenesis:
1. Strong association with asbestos
exposure
2. Smoking
3. Chromosomal abnormalities
Gross appearance

Multiple nodules studding the pleura or
diffuse thickening of the pleura.
Gross appearance
Microscopy

1.
2.
3.
Two types:
Epithelioid type:consists of cuboidal or
columnar cells forming papillary or tubular
structures resembling adenocarcinoma.
Sarcomatoid type: consists of spindle
shaped cells resembling fibrosarcoma.
Mixed type: both epithelioid & sarcomatoid
components
Metastatic tumors
Are more common then primary tumors
 Most of metastasis is from lung, breast
& GIT.

Laboratory investigations in lung
diseases
Complete blood count
 X-Ray, CT Scan, MRI
 Sputum cytology
 Bronchial washings/lavage/brushings
 FNAC of lung
 Lung Biopsy
 Pleural tap for pleural fluid examination

Sputum cytology

Is the tracheobronchial secretions.
Collection of sputum

Early morning sample is preferred as it
represents the pulmonary secretions.
Sputum examination
Macroscopic examination
 Microscopic examination
 Sputum culture

Macroscopic examination
Volume: a 24 hrs sputum is measured in
chronic bronchitis, lung abscess, bronchial
asthma. An increasing volume of sputum
indicates bad prognosis.
2. Colour: normal sputum is clear & colorless.
Yellowish- infectious process like pneumonia
Greenish tint- pseudomonas
Rust colored- pneumococcal pneumonia
Bright red- pulmonary infarction, tuberculosis,
malignancy.
1.
3. Odour: normal sputum is odourless.
Putrid odour- seen in lung abscess,
cavitary tuberculosis.
Microscopic examination
Gram’s stain-detect various bacteria
 Ziehl Neelson’s stain- detect AFB
 Pap’s/ H&E stain- for cytological
examination. Normally sputum shows
few tracheobronchial cells, occasional
squamous cells & inflammatory cells.

Uses of sputum examination
Infectious diseases- Pneumonia, Lung
abscess, Tuberculosis, Fungal infections.
 COPD’s
 Malignancies


Advantages of sputum cytology
Less expensive
 OPD based
 No anesthesia required
 Non invasive

Disadvantages
Detects lesions which opens into
bronchi. Peripheral lung lesions may be
missed.
 Difficult in children, comatose patients.
 Contamination with oral secretions.

Bronchial washings
An bronchoscope is passed via trachea
into bronchioles & about 5ml of
balanced salt solution is introduced.
 Solution introduced is aspirated back &
collected in a sterile container.
 Solution is smeared, stained with PAP’s
stain & examined.

Advantages
No dilution with oral secretions
 Useful in children

Disadvantages
Invasive procedure
 Costly
 Requires anesthesia

FNAC Lung
Fine needle aspiration is useful in
peripheral lung lesions which are
missed with sputum examination &
Bronchoscopy.
 Adv:OPD based, less expensive
 Dis:invasive procedure, not hit the
lesion,
