Interstitial & infilterative Lung Diseases Dr.kassim.M.sultan F.R.C.P

 Upon completion of this lecture the students will be able to :  Define Interstitial & infiltrative Lung Diseases  To know their etiological causes  Describe their clinical features  Illustrate ways of diagnosis  Management of Interstitial & infiltrative Lung Diseases Objectives:

Definition: Heterogeneous group of conditions associated with diffuse thickening of the alveolar walls with inflammatory cells. There is loss of capillary&alveolar function with collagen&fibrous tissue formation. Can occur in isolation or in connection with other collagen diseases. They share common clinical,physiologic&radiologic backgrounds.

Classification: 1-Ideopathic interstitial pneumonias which subdivided into usual interstitial pneumonia(idiopathic pulmonary fibrosis)&diseases other than IPF like Cryptogenic organizing pneumonia. 2-granulomatous diseases like sarcoidosis. 3-drug induced& CTD induced DPLD. 4- other histolocytological types.

Etiology: 1-Ideopathic interstitial pneumonia e.g. IPF 2-Hypersensitivity pneumonitis due to exposure to organic dusts e.g. farmers lung, Byssinosis (cotton, textiles),birds breeder lung(pigeon fanciers) 3-pneumoconiosis due to exposure to inorganic dust e.g. coal workers pneumoconiosis, silicosis(metal grinding), asbestosis(building renovation, pipe & boiler lagging), beryllosis (electrical industries) 4-pulmonary eosinophilia due to helminthes like a scaris, drugs like nitrofurantoin, chlorpropamide, imipramine, fungi like aspergilla.

Clinical features: History of exposure to organic, inorganic dusts & drugs. Occupation and environmental history: Hypersensitivity Pneumonitis & pneumoconiosis Dyspnea on exertion, then on rest. Dry cough, fatigue, weight loss. Pleuritic chest pain. Hemoptysis & pulmonary osteoarthropathy are rare.

Physical signs: May be normal. Cyanosis and clubbing common in IPF. tachypnea and bibasilar end-inspiratory dry crackles in lower zones posteriorly & laterally. signs of cor-pulmonale in advanced disease. Extrapulmonary signs, including lymphadenopathy or uveitis, may be present in sarcoidosis and arthropathies in connective tissue disorder.

Finger clubbing is present in a more than 50% of the patients with IPF.

Investigations: Increased inflammatory markers(ESR,CRP). ECG: usually normal unless pulmonary hypertension is present; then it demonstrates right-axis deviation, right ventricular hypertrophy, or right atrial enlargement or hypertrophy. Antinuclear antibodies and anti-immunoglobulin antibodies (rheumatoid factors) are identified in some patient. Serum precipitins confirm exposure when hypersensitivity pneumonitis.

Investigations: Chest X-Ray: may be normal or most commonly reveals a bibasilar reticular or reticulonodular pattern. HRCT is superior to the plain chest x-ray for early detection and confirmation of suspected ILD. Pulmonary Function Testing: *Forced expiratory volume in one second (FEV 1 ) and forced vital capacity (FVC) are reduced. *The FEV 1 /FVC ratio is usually normal or increased. *reduced total lung capacity, reduction in the diffusing capacity of the lung for carbon monoxide (DL CO ).

Idiopathic pulmonary fibrosis. Small volume lungs with extensive reticular shadowing and early ‘honeycombs’ in the lower zones

IPF– HRCT. Coarse reticular bibasilar fibrosis resembling ‘honeycombing’. Idiopathic pulmonary fibrosis

Investigations: Blood gases: decrease po2&pco2,respiratory failure type I with compensatory respiratory alkalosis Bronchoscopy & Bronchoalveolar Lavage: 1-Lymphocytosis in Sarcoidosis & HP. 2-neutrophilia in pneumoconiosis & IPF. 3-eosinophilia in eosinophilic lung diseases. 4-malignant cells in lymphoma & alveolar cell ca. *lung biopsy: bronchial or trans bronchial by F.O.B, open lung biopsy by thoracotomy & VATS(video-assisted thoracoscopic surgery).

General approach to treatment: High concentration of o2. Treatment of respiratory tract infection. Remove from offending stimuli. Anti-inflammatory drugs like corticosteroid or immunosuppressive.

Idiopathic pulmonary fibrosis: most common form of idiopathic interstitial pneumonia. generally a disease of the elderly, being uncommon before the age of 50 years. gradual onset exertion breathlessness and cough. Finger clubbing may be observed in 25-50% of cases Constitutional symptoms like fever, fatigue, arthralgia, weight loss. Fine (Velcro)basal late inspiratory crackles that not disappear on coughing.

Investigations: CXR Peripheral and basal reticular shadowing, may extend to other zones, sometimes with honeycombing. HRCT features include bilateral, peripheral, and sub pleural reticulation, with honeycombing, traction bronchiectasis, architectural distortion, and minimal or no ground-glass change. Pulmonary function tests often reveal a restrictive pattern, a reduced DL CO.

Investigations: Arterial hypoxemia that is exaggerated or elicited by exercise. BAL is not routinely required and is rarely helpful. Typically shows neutrophilia, sometimes mild eosinophilia. Marked eosinophilia (>20%) or lymphocytosis (>50%) should raise possibility of alternative diagnosis. Trans bronchial biopsies are not helpful in making the diagnosis of UIP.

Differential diagnosis: drug-induced lung disease. chronic Hypersensitivity Pneumonitis. Connective tissue diseases. Bronchiectasis (presence of hemoptysis, coarse crackles, productive cough of copious amount of sputum favors bronchiectasis).

Treatment: Supportive :home o2,oral pholcodine. Prednisolone 40-60mg/day, then re-assess lung function after 1 month(increase in VC or TLCO by 10-15% or more) or stable: slowly reduce prednisolone dose (e.g. reduce by 5 mg weekly to 20 mg and review. if no worse, reduce by 5 mg a month to maintenance dose of 10 mg and continue at 10 mg for one year, and consider further reduction after this). combination treatment with azathioprine 1.5-2mg/kg (immuran) to decrease steroid dose.

Treatment: Lung transplant in end stage disease & when there is no response to steroid. Further developments: Pirfenidone (antfibrotic), interferongamma1b, or N-acetylcysteine, bosentan(endotheln receptor 1 antagonist), imatinib, etanercept.

Complications: 1-Respiratory failure type I. 2-Cor-pulmonale. Prognosis: Median survival is 5-7 years.

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