Hypersensitivity pneumonitis in a machinist.

Hypersensitivity pneumonitis (HP), or extrinsic allergic alveolitis, is a patchy, interstitial lung disease that involves an immunologic reaction of the lung to repeated inhalation of foreign antigens. In this report, we describe a machinist with exposure to metalworking fluids (MWFs) and biopsy-confirmed HP. Return to work, which could be equated with a retrospective workplace-specific bronchoprovocation test, proved that working within an environment in which MWFs were used was associated with clinical deterioration in the patient's pulmonary status and with clinical improvement after removal from exposure.