Case of the quarter: Unilateral balsalazide-induced eosinophilic pneumonia in an ulcerative colitis patient

We report a case of unilateral eosinophilic pneumonia secondary to balsalazide monotherapy for ulcerative colitis. After commencing balsalazide, the patient  presented  with  a  history  of  cough,  progressive  dyspnoea  and  lethargy. Blood counts revealed peripheral eosinophilia. Her chest radiograph showed left-sided  infiltration,  and  high-resolution  computerised  tomography  demonstrated widespread  nodular  shadowing  and  ground  glass  opacifiction  in  the  left  lung. The  right  lung  was  normal. Transbronchial  lung  biopsy  confirmed  eosinophilic pneumonia. There  was  rapid  clinical  and  radiological  improvement  after  with-drawing  balsalazide.  Drug-induced  eosinophilic  pneumonia  has  been  described with  mesalazine  and  sulfasalazine,  but  no  case  reports  of  balsalazide-induced eosinophilic pneumonitis have been found.