Acute kidney injury in the setting of AIDS, bland urine sediment, minimal proteinuria and normal-sized kidneys: a presentation of renal lymphoma

Acute kidney injury in HIV patients is primarily related to HIV-mediated viral or immunological disease or to treatment-related toxicity (tenofovir). Neoplasms are a rare cause of non-obstructive acute kidney injury, primarily because when they occur, they manifest as discrete masses and not as diffuse infiltration of the renal parenchyma. Diffusely infiltrating tumors include carcinoma of the renal pelvis invading the renal parenchyma, renal lymphoma, squamous cell carcinoma (from lung) metastasizing to the kidney and infiltrating sarcomatous type of renal cell carcinoma. To be classified as a true case of renal lymphoma, the tumor should have escaped detection on routine imaging preceding biopsy, and lymphoma-associated renal failure/ nephrotic proteinuria should have given rise to the indication for kidney biopsy. We present here a case of an acute kidney injury due to renal lymphoma in a patient with acquired immune deficiency syndrome that manifested clinically as bland urine sediment, minimal proteinuria and normal-sized kidneys. Chemotherapy resulted in complete reversal of acute kidney injury.