Diffusion-Weighted Magnetic Resonance Imaging and Apparent Diffusion Coefficient Mapping Detect Kidney Infiltration in Acute Myeloid Leukemia: A Case Report.

We describe a case of 70-year-old man with type 2 diabetes and myelodysplastic syndrome progressing to acute myeloid leukemia (AML) who presented with rapidly worsening kidney function. Although computed tomography imaging of the patient's kidneys was unremarkable, subsequent magnetic resonance imaging (MRI) showed high signal intensity on diffusion-weighted imaging and low signal intensity on the apparent diffusion coefficient map in the kidneys. A kidney biopsy from the region that exhibited abnormal findings on MRI showed blast cell infiltration within the kidney capsule and proximal tubules. After initiating venetoclax and azacitidine therapy, the patient's AML promptly improved, and his kidney function rapidly recovered. Kidney infiltration in AML is rare and difficult to diagnose because of nonspecific symptoms and the limited sensitivity of plain computed tomography. This case highlights the value of MRI, especially diffusion-weighted imaging and apparent diffusion coefficient mapping, for the detection of blast cell infiltration in the kidneys. To our knowledge, this is the first case in which kidney infiltration was identified in a patient with AML based on imaging findings. This case supports the consideration of MRI as a noninvasive diagnostic tool in patients with unexplained kidney dysfunction and hematologic malignancies.