[Organizing pneumonia during treatment with mesalazine]

The distinction between extra-intestinal manifestations of ulcerative colitis (UC) and drug-induced pneumonia can often be difficult.

We describe the case of a 72-year-old male who presented fever and sub-acute respiratory insufficiency, after 4 months of treatment with mesalazine for ulcerative colitis (UC). Initial tests found serum C-reactive protein, eosinophil count and total IgE to be elevated. Routine bacteriological, fungal and mycobacterial cultures were negative. Bronchoalveolar lavage fluid cellularity was normal with elevated lymphocyte, neutrophil, and eosinophil counts (35 % mononuclear cells, 23 % lymphocytes, 28 % neutrophils, 14 % eosinophils). The diagnosis of organizing pneumonia (OP) with eosinophilic pneumonia component was confirmed after examination of a lung biopsy specimen. Clinical improvement occurred after cessation of mesalazine and initiation of prednisolone (1mg/kg/day). Nine months later, a recurrence of gastrointestinal symptoms required a 5 months reintroduction of an amino salicylate by topical therapy (4- acide aminosalicylique [ASA enemas]). There was no resurgence of the pneumonia.

Organizing pneumonia is a rare extra-intestinal manifestation of UC. There was no resurgence of OP after amino salicylate enemas rechallenge but mesalazine-induced pneumonia cannot be excluded.