Pulmonary fibrosis

• Finger clubbing and respiratory crepitations are commonly found in pulmonary fibrosis.

• Conditions that cause fibrosis or scarring of the lungs give restrictive patterns on spirometry.

Drugs which may cause pulmonary fibrosis include: 

• Cytotoxic drugs e.g. busuplhan, bleomycin, methtrexate (hanges induced may resolve despite continuing treatment), cyclophosphamide, carmustine

• Antibiotics e.g. nitrofurantoin

• Cardiac drugs e.g. hydralazine, amiodarone, tocainide

• Opioids e.g. heroin abuse

Extrinsic allergic alveolitis (EAA) / hypersensitivity pneumonitis

• a diffuse inflammatory condition of the gas exchanging tissues of the lung resulting from hypersensitivity to inhaled organic dusts. Small antigenic particles (0.5–5 micrograms) deposit in the alveoli of the lung (e.g. bacteria, fungal spores, microbial species and antigens derived from animal, vegetable and chemical sources) triggering an inflammatory reaction. It is important to recognise EAA as it may result in acute or chronic illness. 

• In chronic cases, if the diagnosis is not established and exposure to the antigen(s) stopped, progressive irreversible lung disease may occur with fibrosis and respiratory failure. There are a wide variety of respiratory antigens

• Diagnosis: based on clinical symptoms, evaluation of unexplained infiltrative lung disease, exclusion of infectious causes and restrictive changes in pulmonary function. 

• Farmer's lung and lung disease in people working in muschroom growing units are both caused by thermophilic actinomycetes. 

• Pigeon-fancier's lung is caused by avian proteins present in the dry dust of the droppings and sometimes in the feathers.

• Alternaria is a genus of ascomycete fungi and a major plant pathogen. These organisms are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma. They readily cause opportunistic infections in immunocompromised people.

• Aspergillus clavatus causes maltworkers lung.

• Protozoa: rare cause of pulmonary infections and pneumonitis.

Interstitial lung disease (idiopathic pulmonary fibrosis)

Sarcoidosis

• Parotid gland swelling, erythema nodosum, hypercalcaemia, bilateral hilar LN