Following renal ultrasound images were obtained from a patient with diffuse large B-cell lymphoma with extensive spread all over the body including central nervous system. Indication for the study: acute on chronic renal failure (CKD stage III).

Note the kidneys are enlarged bilaterally with irregular outlines and multiple hypoechoic lesions throughout the parenchyma. On Doppler images, these lesions do not show much internal vascularity. These findings are suggestive of lymphomatous infiltration of the kidneys, which was confirmed by PET scan (positron emission tomography), seen as bright hypermetabolic lesions. Though acute kidney injury from this entity is rare, kidney is the most common extrareticular site of leukemic and lymphomatous infiltration. Tumor-cell infiltrates in the kidney are seen in up to 30% of patients with lymphoma and up to 60% of patients on autopsy. Hydronephrosis may be seen depending on the site of involvement. Below is the CT scan image demonstrating enlarged irregular kidneys with cortical thickening and perinephric stranding.

Below is another case of follicular lymphoma involving the kidney in the form of an ill-defined solitary mass. These kind of isoechoic masses are very difficult to identify on POCUS exams. First, lets see images obtained by an inexperienced user. He/she called it ‘normal left kidney’.

Repeat US done by an expert showing the mass. Note the mass on contrast-enhanced CT scan.