Interstitial pulmonary diseases And Interstitial Pulmonary fibrosis pathology, diagnosis, management

 Group of chronic, non malignant, non infecious diseases characterized by inflammation and infiltration of the interstitial tissue of the lung with inflammatory cells with derangement of the alveolar walls and perivascular and perilymphatic tissues .
Pathological stages
(1) Acute stage:
There is acute damage to capillary and alveolar epithelial
cells leading to interstitial edema. This stage may either resolve
completely or progress to acute interstitial pneumonia.
(2) Chronic stage:
There is extensive deposition of collagen resulting in wide spread fibrosis. In
addition there is disruption of the alveolar spaces, which are lined with atypical
cuboidal cells.
(3) End stage:
The disease eventually progresses until the lung becomes honey combed.
The entire alveolar and capillary network is replaced with fibrous tissue with dilated
spaces. The capillary bed is decreased and the involved lung has no remaining gas
exchange function.


The causes of the interstitial pulmonary disease may lead to:

==> Triggering of immune system?

Causes of Interstitial pulmonary diseases

1- Dust (occupational lung diseases)
- Inorganic dust (Pneumoconiosis)
- Organic dust (Hypersensitivity pneumonitis)

2- Sarcoidosis

3- Collagen diseases ( Rheumatoid diseases, SLE, Scleroderma, Ankylosing spondylitis )

4- Idiopathic (cryptogenic fibrosing alveolitis)

Clinical picture of Interstitial pulmonary diseases

Features of interstitial pulmonary diseases:

1- Features of the Cause e.g. history of exposure, arthropathy.

2- Dyspnea + [ Crepitations (fine with leathery character) - Cough (dry and irritative) - Clubbing - Cor pulmonale - Cyanosis ]


1. X-ray, diffuse lung infiltrates (miliary shadow)
Or diffuse reticulo nodular pattern.

2. Blood gases showing diffusion defect (tt O2)

3. CT scan especially high resolution CT.

4. Lung biopsy (open or transbronchial)

5. Examination of bronchoalveolar lavage fluid.

6. Pulmonary function tests showing diffusion defect (early) with superadded restrictive hypoventilation (late).

7. LAB tests for the cause e.g ANA or Rheumatoid factor.

Treatment of Interstitial pulmonary diseases :

1) Avoid the cause
2) Antioxidants.
3) Bronchodilators.
4) Steroids (early with active disease).
5) Cytotoxic drugs can be used e.g. cyclohosphamide with steroid.
6) Pneumococal and influenza vaccines.
7) Oxygen therapy and treatment of right sided failure.
8) Lung transplantation.

• Colchicine, penicillamine, interferon and cyclosporine have been tried, however their role remains to be determined.

• Corticosteroids are the mainstay of therapy and are indicated when lung biopsy show an active cellular process without extensive fibrosis. Large doses
e.g prednisone 1 mg/kg/day may be used initially with physiologic and radiographic monitoring. It there is improvement after 6 weeks, the dosage should be tapered gradually with low dose maintenance if needed plus frequent monitoring to detect relapse.

• If no improvement with steroid alone, immunosuppressive agents may be used either alone or in combination with steroids. Azathioprine is the most widely used, cyclophosphamide and chlorambucil also have been used.

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