Probable occupational pneumonitis caused by inhalation of crushed clozapine.

We present a case of non-specific interstitial pneumonia (NSIP) probably caused by exposure to inhaled clozapine powder. The patient worked in a pharmacy and crushed clozapine tablets over several years. She presented with insidious onset of breathlessness and had mild hypoxia. High-resolution computed tomography demonstrated centrilobular nodules with peribronchial consolidation. Lung biopsy revealed a mixed cellular and fibrotic NSIP. Her symptoms and radiological findings resolved once exposure to clozapine powder ceased. The clear temporal relationship between increased exposure to inhaled clozapine and the development of NSIP, followed by the subsequent resolution on cessation of exposure, strongly suggest an occupational cause. Both the active ingredients and the excipients of powdered medicine may be responsible for causing pneumonitis in chronic exposure.