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. Increased hydrostatic pressure, as in congestive cardiac failure.

2. Increased vascular permeability, as in Pneumonias.

3. Decreased osmotic pressure, as in Nephrotic syndrome.

4. Decreased lymphatic drainage, as in Mediastinal carcinomatosis.

Clinical features

Pleuritic chest pain- increases on inspiration, coughing, sneezing

Dyspnea

Clinical features

500ml of fluid should be present to produce the signs

1. Bulging of intercostal spaces on the affected side

2. Diminished mobility of chest wall3. Shift of mediastinum to the opposite side4. Stony dullness on percussion5. 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. Hydrothorax2. Haemothorax3. 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

Exudate type1. Serofibrinous2. Suppurative/Empyema thoracis3. Haemorrhagic

Serofibrinous type

Causes--Pneumonias, Lung abscess,

Bronchectasis,-Tuberculosis-Rare causes-Rheumatoid arthritis,

SLE, Radiation injury.

Purulent/Empyema type

Accumulation of pusCauses--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. CBC2. Sputum examination-gram’s, ZN,

Cytology3. X-Ray- Homogeneous

opacity(150ml)4. CT, MRI- 50ml5. Pleural tap- for pleural fluid

examination

Pleural fluid examination

Lymphocytic predominance-tuberculosis, fungal infections, carcinoma

Polymorphic predominence-acute bacterial infections

Presence of pleomorphic cells- malignancy

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 wall3.Therapeutic:Was once used in treatment of

tuberculosis

Types of pneumothorax

1. Closed type- the opening is very small & heals spontaneously

2. Open type- the opening is large & remains patent

3. 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. Compression of pleura on lung may lead to Atelactasis & leading to Respiratory distress.

2. Tension pneumothorax- results if the defect acts as ball valve permitting entry of air & preventing escape of air.

Pleural tumors

1. Primary-2. Benign mesothelioma, malignant

mesothelioma3. secondary

Solitary fibrous tumor

Very rare Benign tumor Not related Asbestos exposure.

Malignant mesothelioma

Etiopathogenesis:1. Strong association with asbestos

exposure2. Smoking3. Chromosomal abnormalities

Multiple nodules studding the pleura or diffuse thickening of the pleura.

Gross appearance

Gross appearance

Microscopy Two types:1. Epithelioid type:consists of cuboidal or

columnar cells forming papillary or tubular structures resembling adenocarcinoma.

2. Sarcomatoid type: consists of spindle shaped cells resembling fibrosarcoma.

3. 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 examination1. 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 pneumoniaGreenish tint- pseudomonasRust colored- pneumococcal pneumoniaBright red- pulmonary infarction,

tuberculosis, malignancy.

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,