Chronic myelomonocytic leukemia (CMML) is a rare hematologic disorder that infrequently causes acute kidney injury (AKI). CMML can transform into acute myeloid leukemia (AML), which can be accompanied by a deterioration in kidney function. However, severe AKI due to extramedullary manifestations of AML is rare. Herein, we present the case of a 67-year-old male patient with CMML that transformed into AML with severe AKI necessitating hemodialysis. The cause of the AKI was the AML transformation. The patient, with stable kidney function after chemotherapy for CMML, presented with a sudden decline in kidney function. Hemodialysis was initiated because of severe AKI, and histopathologic evaluation of the kidney biopsy specimen revealed severe, diffuse mixed inflammatory cell infiltrates in the interstitium and c-kit-immunopositive myeloblast-like cells. A bone marrow biopsy was performed because of the kidney biopsy findings suggesting that leukemic infiltration led to the diagnosis of AML. The patient received chemotherapy for AML, and his kidney function recovered. As illustrated in this case, severe AKI can develop as an early extramedullary manifestation during transformation from CMML to AML. Therefore, in patients with CMML and rapidly declining renal function, transformation into AML should be considered and histopathologically confirmed by kidney biopsy.
Keywords: acute kidney injury; acute myeloid leukemia; chronic myelomonocytic leukemia; kidney biopsy; leukemic infiltration.