Interstitial lung disease and weight loss

A 52 year old man presented to the outpatients’ department with dyspnoea, dry cough, and weight loss. The breathlessness had progressed over two years. Also 41 kg of weight loss in 12 months was concerning.

In seeking a cause for this, he underwent bronchoscopy two weeks before his outpatients’ appointment, and since then his breathlessness had rapidly worsened. At the consultation he was unable to complete a sentence and was in a wheelchair.

Questions

1. What is the main abnormality shown in the figure? Suggest some causes.
2. What would you expect to find on examination? What is the immediate management?
3. What are the differentials for the chronic aspect of this presentation?
4. What risk factors should be identified in the patient’s social history?
5. What would you do next? (6) What was the outcome?
   

Answers

Chest radiograph on admission

1. There is an absence of lung markings in the left upper zone of the chest radiograph. The aorta, trachea, and opposite lung are displaced to the right. This corresponds with a tension pneumothorax, defined as air under pressure in the pleural cavity. This condition can come about after a primary event, such as a spontaneous occurrence, after trauma, or as a result of medical intervention. In this case the earlier bronchoscopy may be causative. It could also be a secondary result of underlying lung pathology.
2. Signs would be localised to the area of abnormality, with reduced expansion, hyper-resonance to percussion and decreased breath sounds, and displacement of mediastinal structures to the right. Management is dependent on the presence of dyspnoea or positive radiographic findings. If a primary cause is identifiable aspirate in the first instance. If this is not successful, or there is underlying secondary lung pathology in a patient over 50, a chest drain should be sited.¹ In view of evidence of tension a chest drain was inserted and the patient was admitted for investigation.
3. There are many putative causes of coexisting weight loss and breathlessness (table).
4. A comprehensive respiratory history should assess smoking in pack years, exposure to animals, occupational hazards such as asbestos or farming, and recent travel or tuberculous contact. In this case there was no significant occupational indication. The patient was not a smoker and had never smoked. Cats and birds are known causes of lung pathology, though he denied having any pets of his own on direct questioning.
5. A full respiratory examination showed signs of a pneumothorax and shift of mediastinum to right side as well as fine inspiratory crackles in the right lung. The chest radiograph showed a tension pneumothorax and diffuse reticulonodular shadowing. These findings suggest interstitial lung disease. Serum precipitins to allergens were tested in order to rule out hypersensitivity pneumonitis.
6. On further questioning by medical students he stated that he had no pets. However, his mother has five parakeets, and he lives with her. They were kept in the kitchen, where their cage was cleaned, promoting spread of allergenic particles. Serum precipitins were strongly positive to avian proteins and to cockatiel specifically, confirming the bird exposure to be significant. The patient was advised to avoid this irritant. A later review confirmed this course of action to be effective, as the patient had both gained weight and was no longer breathless.
   

Discussion

Bird exposure is a proven cause of hypersensitivity pneumonitis, in which the repeated inhalation of avian antigens provokes a hypersensitivity reaction in susceptible people, leading to restrictive lung disease.

Weight loss is a common but lesser known symptom. It is one of five significant predictors for hypersensitivity pneumonitis. In the presence of these factors a diagnosis can be made confidently without further tests. The other four factors are exposure to a known antigen, recurrent respiratory symptoms soon after exposure, positive antibodies to that antigen, and inspiratory crackles on auscultation.²

Thorough history taking should include asking specifically about birds, as patients do not necessarily consider them as pets. A recent letter recommended asking about bird years, in the same way that smokers are assessed for pack years for judging exposure.³

The treatment is to avoid exposure to antigen. In acute situations, oxygen therapy is needed and sometimes steroids are used in severe cases.

Prognosis is excellent in the acute phase. The chronic presentation has a variable clinical course with insidious development of breathlessness and pulmonary fibrosis. Older age and extensive exposure have a poorer long term outlook. Even after birds are removed, persisting avian antigens may remain in the home environment. This may account for the substantial five year mortality rate of 30%.⁴

Sadat Edroos, final year medical student
Email: sadat@edroos.co.uk

Laura Samuel, final year student, Warwick Medical School

P D J Handslip, consultant physician, George Eliot Hospital, Nuneaton


studentBMJ 2005;13:309-352 September ISSN 0966-6494

1. Longmore M, Wilkinson IB, Rajagopalan S. Oxford handbook of clinical medicine. 6th ed. Oxford: Oxford University Press, 2004.
2. Lacasse Y, Selman M, Costabel U, Dalphin JC, Ando M, Morell F, et al. Clinical diagnosis of hypersensitivity pneumonitis. Am J Respir Crit Care Med 2003;168: 952-8.
3. Judson MA, Sahn SA. Bird-years as well as pack-years. Chest 2004;125: 353-4.
4. Emedicine. Hypersensitivity pneumonitis. www.emedicine.com/med/topic1103.htm (accessed 17 Aug 2005).