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 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 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 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 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 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 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 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 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 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 Primary- Benign mesothelioma, malignant mesothelioma secondary

Solitary fibrous tumor Very rare Benign tumor Not related Asbestos exposure.

Malignant mesothelioma Etiopathogenesis: Strong association with asbestos exposure Smoking Chromosomal abnormalities

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

Gross appearance

Microscopy 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. Colour: normal sputum is clear & colorless. Yellowish- infectious process like pneumonia Greenish tint- pseudomonas Rust colored- pneumococcal pneumonia Bright 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,

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