Acute Kidney Injury Due to Ureteral Damage by Needle-Shaped Crystals Associated With Boron Neutron Capture Therapy.

A 77-year-old man was referred to our department because of macrohematuria, oliguria, and a serum creatinine level of 2.47 mg/dL during boron neutron capture therapy (BNCT) for oropharyngeal cancer. At baseline, his creatinine level had been 0.98 mg/dL. The vital signs and physical examination were normal. A urinalysis showed protein and numerous red cells per high-power field, and needle-shaped crystals were observed. A plane computed tomography showed hematoma within the extensive ureter. However, hydronephrosis was not recognized. Immediate discontinuation of BNCT and supplemental fluids reduced gross hematuria, increased urine, and creatinine decreased to 0.97 mg/dL. BNCT is an innovative radiation therapy that targets tumor cells by inducing a nuclear reaction between 10B and neutrons within the tumor. However, there have been no reported cases of treatment-related boron crystals causing ureteral injury that leads to acute kidney injury, and oncologists should be aware of this potential risk.