Objective To investigate the clinical features of hypersensitivity pneumonitis and misdiagnosis causes. Methods The morbidity, misdiagnosis, progression, treatment, recovery, relapse and experience of treatment of a case with hypersensitivity pneumonitis was retrospectively analyzed. Results Patients with hypersensitivity pneumonitis usually have a contact history of organic dust, and clinical manifestations are nonspecific. Chest radiography shows wandering pattern of multiple reticular or patchy infiltration shadows. Lung function tests showrestricted ventilation and impaired diffusion. Blood eosinophil is usually normal. Lymphocyte and sedimentation antibody in serum and bronchoalveolar lavage fluid may still be normal. Pathohistology is complicated, with a progression from acute inflammation to chronic fibrosis. Systemic steroid should be prescribed as soon as possible. Antigen avoidance should be emphasized. Conclusions Clinical symptoms of hypersensitivity pneumonitis is atypical, which may be easily misdiagnosed. The contact history, clinical features, chest radiography, laboratory examination and pathological changes should all be considered in such cases.
