A 59-year-old woman diagnosed with acute myeloid leukemia received successfully an allogeneic hematopoietic stem cell transplantation from an HLA-compatible unrelated donor following a reduced-intensity conditioning. The GvHD prophylaxis regimen was mycophenolate mofetil and cyclosporine. In the post-transplantation phase, the patient presented several complications, such as reactivation of CMV disease (CMV serostatus: D+, R+). Foscarnet was initiated and phosphonoformate crystalluria (proven by infrared spectrometry) was observed 7 days after onset of therapy associated with renal tubular epithelial cells in urine sediment. No hematuria was observed. The patient developed AKI KDIGO stage 1 24 days after foscarnet initiation.
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.