Hypersensitivity pneumonitis. High resolution CT findings with pathological correlations. A pictorial essay.

The diagnosis of HP is based upon the association of antigen exposure history, compatible clinical and radiological findings and high titres of precipitating serum antibodies to specific antigens. The manifestations of HP are usually divided into three typesacute, sub-acute and chronicbut a significant overlap exists. The clinical spectrum probably reflects different factors, specific to the subject, as well as the frequency and degree of exposure. The aim of this pictorial essay is to present the more common presentations of HP.