Disopyramide-induced pneumonitis, diagnosed by lymphocyte stimulation test using bronchoalveolar lavage fluid

A 72-year-old man was admitted to our hospital with fever and cough. He had been on disopyramide treatment for nine days to control cardiac arrhythmia. On admission, chest X-ray examination revealed reticulonodular opacities in both lungs, and impending respiratory failure was evident. A differential cell count of the bronchoalveolar lavage fluid (BALF) showed a marked increase of lymphocytes. A lymphocyte stimulation test (LST) for disopyramide using BALF was positive, although the test using peripheral blood was negative. This case suggests that LST using BALF is useful for the diagnosis of drug-induced pneumonitis.