A 71-year-old woman diagnosed with acute myeloid leukemia underwent, while in complete remission, a nonmyeloablative allogeneic hematopoietic stem cell transplantation with HLA-compatible unrelated donor. Conditioning regimen consisted in fludarabine and total body irradiation; graft-versus-host disease (GvHD) prophylaxis consisted of mycophenolate mofetil and ciclosporine. Following transplantation, the patient presented multiple complications such as a reactivation of CMV disease (CMV serostatus: D−, R+). Ganciclovir was administered without effect on the viral load of CMV. Hence, based on in vitro documentation of resistance of CMV to ganciclovir, the patient was switched to foscarnet. Phosphonoformate crystalluria (proven by infrared spectrometry) was observed 14 days after the onset of foscarnet therapy and associated with a nonglomerular hematuria and renal tubular epithelial cells in urine sediment. Progressive elevation of serum creatinine concentration occurred (AKI Kidney Disease: Improving Global Outcomes [KDIGO] stage 3), despite adaptation of foscarnet doses to kidney function. The patient died after probable fungal bronchopneumonia and septicemia while still on foscarnet.
A 73-year-old man, previously diagnosed with myelodysplastic syndrome, underwent hematopoietic stem cell transplantation from an HLA-haploidentical donor. CMV serostatus: D−, R−. GvHD prophylaxis consisted of post-transplant cyclophosphamide, tacrolimus, and mycophenolate mofetil. In the post-transplantation phase, the patient presented several complications, including oral herpes (HSV1) infection. Because of proven in vitro valaciclovir resistance, foscarnet was introduced: phosphonoformate crystalluria was observed at day 11 after onset of therapy. Neither red blood cells nor any other cells were seen in the urine sediment. The patient developed AKI KDIGO stage 2 at day 12. The viral infection was effectively treated, but the patient died 2 months later due to an invasive fungal infection.