APMIS : acta pathologica, microbiologica, et immunologica Scandinavica
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There is no consensus on the classification of the diagnostic certainty of hypersensitivity pneumonitis (HP) based on the histopathological findings. This retrospective study aimed to describe the clinical and histopathological spectrum of HP. Herein, we also propose different grades of diagnostic certainty. ⋯ Based on the various combinations of histopathological findings, the cases were classified as 'definite', 'probable', and 'possible' HP in 56.7%, 33.3%, and 10%, respectively. Chronic HP was diagnosed in 56.7% cases based on the presence of fibrosis on histopathology. The histopathological diagnosis of subacute or chronic HP did not corroborate with the disease duration, and 17.6% of the subjects with duration of symptoms of <6 months had evidence of fibrotic disease on histopathology.