Seminar

Cryptogenic fibrosing alveolitis

Prevalence

There are few data on the epidemiology of CFA. Mortality from CFA increased in England and Wales from 330 in 1979 to 700 in 1988.² Similar increases occurred in other countries, except in the USA,² where only about 25% of patients known to have IPF had this diagnosis on the death certificate. The prevalence of the disease was estimated in 1990 to be six per 100 000 in Nottingham, UK.³ In the USA, it was estimated in 1994 to be 29 and 26 per 100 000 in men and women, respectively,⁴ about five

Aetiology

In Europe, the term CFA includes lung fibrosis associated with collagen-vascular/connective-tissue disease. In North America, the term IPF is used for patients with CFA, but it does not include patients with collagen-vascular disease. However, many patients with CFA but no collagen-vascular disease have autoantibodies, including rheumatoid factor or antinuclear factor and even antibodies to lung proteins, which suggests the possibility of an autoimmune disorder.

The aetiology of CFA is unknown.

Pathology and pathogenesis

The histopathological findings can be classified into three broad patterns based on the degree of inflammatory alveolitis and fibrosis.¹

A cellular pattern (desquamative interstitial pneumonitis), with intra-alveolar and septal inflammation, type II cell hyperplasia, increased numbers of lymphocytes, and little fibrosis, is widely thought to be the earliest manifestation of the disease. Some investigators, however, regard desquamative interstitial pneumonitis as a separate entity. It is rare

Clinical features

CFA affects people aged between 40 and 70 years; there is a male to female ratio of two to one. Most patients present with a 1–3-year history of non-productive cough and slowly progressive shortness of breath. Typically, patients have bilateral basilar crackles and clubbing of the fingers. The British Thoracic Society study of CFA defined cases as having bilateral interstitial shadowing on chest radiography, with bilateral basal inspiratory crackles, and lung-function results showing a

Diagnosis

The diagnosis of CFA in a patient presenting with progressive breathlessness is generally based on the findings of finger clubbing, bilateral basilar crackles, a typical appearance on chest radiography, and restrictive defect with impaired gas transfer on lung-function testing. The diagnosis of CFA in the British Thoracic Society study was made on clinical grounds in 60% of cases.¹⁵

All known causes of fibrosing alveolitis should be excluded (panel 1). A very thorough history of occupational and

Treatment

There remains a great deal of uncertainty about the appropriate treatment of CFA, compounded by the lack of data on the natural progression of untreated disease. The view that CFA remains stable in many patients, particularly in the elderly, is widely held. In the British Thoracic Society study, fewer than 50% of CFA patients were receiving any treatment at entry to the study.¹⁵ The decision not to treat was most commonly made for patients with few or stable symptoms and elderly patients. The