recipient

A 64 year-old man, who received a renal transplant in 1988 for end-stage renal disease due to chronic pyelonephri-tis, developed persistent dry cough, progressive dyspnoea, fatigue and fever, 2 weeks after he was shifted from cy-closporine to sirolimus for recurrent squamous cell car-cinomas. Physical examination was unremarkable except for mild fever. Moderate acute phase reaction (CRP: 5.2 mg/dl) was present and sirolimus trough level was 6 ng/ml. A left lower infiltrate was noted on chest radiograph. He was treated with a course of moxifloxacin without improvement. High-resolution CT scan of the lungs re-vealed bilateral heterogeneous ground-glass opacities pre-dominant in the lower lung zones (Figure 1A), associated with mild interlobular septal thickening. Bronchoalveolar lavage (BAL) disclosed 63 % macrophages, 11 % lympho-cytes and 26 % neutrophils. Specific stainings and culture of BAL fluid samples were negative for bacteria, my-cobacteria, viruses, fungi and parasites. Serological tests for Chlamydia pneumoniae, C. psittaci, Mycoplasma pneu-moniae, Coxiella burnetti and Legionella pneumoniae as well as cytomegalovirus antigenemia remained negative. Sirolimus was discontinued and the patient improved grad-ually, with complete disappearance of the symptoms and normalization ofCRP levelwithin 2weeks.High-resolution thoracic CT scan returned to normal 4 months later (Figure 1B). Sirolimus is a potent immunosuppressive drug, increas-ingly used in solid-organ transplantation for its nephrotoxic-sparing and antitumour effects. Interstitial pneumonitis fol