Sirolimus-associated acute respiratory distress syndrome in a renal transplant recipient

Sirolimus is a new potent immunosuppressive drug used in organ transplantation; its major advantage is the absence of deterioration in renal function. Documented adverse effects include myelosuppression and hyperlipidemia. Recently several cases of sirolimus-associated interstitial pneumonitis have been reported, usually of mild severity. We report a new case that was complicated by a severe acute respiratory distress syndrome, which required several days of mechanical ventilation. No infectious or cardiogenic etiology was documented. Low sirolimus blood levels and acute CD4 lymphocytic alveolitis suggested an immune-related mechanism rather than a direct toxic effect of the drug. The patient recovered after discontinuation of sirolimus and the administration of corticosteroids.