Unusual case of diagnosis of pigeon breeder's hypersensitivity pneumonitis with ventilation-perfusion lung scan.

The authors describe a patient thought to have pulmonary embolism. Results of a perfusion scan were normal, but Tc-99m DTPA aerosol ventilation lung scan showed, in successive views, decreased activity of the deposited aerosol. The lung Tc-99m DTPA clearance was measured and was markedly increased. This suggested possible hypersensitivity pneumonitis, which was later confirmed as pigeon breeder's disease. The decreased activity observed on the DTPA ventilation scan must be directed toward increased lung clearance and its measurement.