Intravascular Foscarnet Crystal Precipitation Causing Multiorgan Failure

We report a case of multiorgan failure resulting from treatment with the antiviral foscarnet in a kidney transplant recipient. Precipitation of foscarnet crystals was confirmed histologically from a biopsy of the transplant using optical and infrared microscopy. In addition to kidney damage resulting from foscarnet crystal precipitation in the tubular lumen and glomerular capillaries, the patient presented with pancreatitis, pancolitis, and myocarditis with shock. Interruption of the treatment led to rapid improvement in her general condition, but did not prevent permanent loss of the kidney transplant. When faced with unexplained multiorgan failure in a patient treated with foscarnet, one should assume this substance to be toxic. A kidney biopsy can confirm this diagnosis.