Haemorrhagic hypersensitivity pneumonitis due to naphthylene-1,5-diisocyanate

Symptoms of hypersensitivity pneumonitis and massive pulmonary haemorrhage occurred in a 24-yr-old male shortly after occupational exposure to naphthylene-1,5-diisocyanate (NDI). The present examination was performed approximately 1-yr after the initial life-threatening haemoptysis and following an uneventful recovery after resection of the middle lobe, which had been identified bronchoscopically as the bleeding source. Histological re-examination of the lung was compatible with hypersensitivity pneumonitis. After a chamber challenge with NDI (5 parts per billion (ppb) for 10 min, 10 ppb for 110 min), rales were heard in both lungs, and a fall in vital capacity and partial pressure of arterial oxygen as well as a rise in body temperature were documented. Isocyanate-specific immunoglobulin-G antibodies could not be detected in the patient's serum, possibly due to the long period without exposure to isocyanates. The authors conclude that naphthylene-1,5-diisocyanate may cause immunological pulmonary haemorrhage. The underlying disease is consistent with hypersensitivity pneumonitis and may be triggered by low concentrations of the diisocyanate.