Idiopathic interstitial fibrosis is a disease characterized by diffuse interstitial fibrosis of unknown etiology and frequently occurs between the ages of 50-70.

Clinical Picture

• Patients present with dry cough and shortness of breath and sometimes with fever, arthralgias and Raynaud's phenomenon.
• Clubbing (40-70%) tachypnea and persistent coarse basal crackles are encountered on physical exam. Often they are using accessory muscles of inspiration for tidal breathing.
• CXR: Normal to reticulonodular to honeycombing. HRCT may show ground glass appearance or honeycomb cysts.  In Desquamative interstitial pneumonitis alveolar features can be recognized..
• PFT shows a restrictive and diffusion defects. Patients are hypoxic and desaturate significantly with exercise.
• In 25-45%, serum cryoglobulins, RF and ANA are present.
• BAL: Predominance of neutrophils.

Pathology

Desquamative Interstitial pneumonitis(DIP), Usual Interstitial Pneumonitis(UIP), Lymphocytic Interstitial Pneumonitis( LIP) are various subgroups, probably of the same disease process.

1. Early IPF: Desquamation predominates where alveolar macrophages fill alveolar spaces (desquamative interstitial pneumonitis or DIP).

2. Late IPF: Inflammation of alveolar walls continues and fibroblast proliferation with collagen formation occurs (usual interstitial pneumonitis or UIP).

Diagnosis

•  By exclusion, it will be necessary to rule out other known causes for fibrosis like Silicosis or drugs. A long list of conditions can give rise to interstitial fibrosis 

• Transbronchial lung biopsy  can identify interstitial fibrosis. Usually need open lung biopsy to confirm.

Treatment

• Thearpy is useful in acute stages when there is significant inflammatory process.
• Once the fibrosis is chronic or if the chest X-ray has been stable for years or if there is honeycombing, therapy is of no benefit.
• Corticosteroids + immunosupressants (cyclophosphamide or azathioprine); anecdotal reports describing colchicine or methotrexate or cyclosporine.
• Oxygen is often prescribed for these patients, probably not influencing pulmonary hypertension.
• In some cases  Plasmapheresis and Lung Transplant are considerations.
• Transplantation: 50% two year survival with single lung.

Prognosis

• In the acute progressive form "Hamman-Rich Syndrome" the prognosis is poor.
• In the chronic form patients can live long with disability.