A case story of a patient with renal biopsy (RB) proven infiltration with lymphoma is given. RB in patient with known malignancy and onset of renal failure was indicated with regard to an atypical picture of kidney involvement (non-enlarged kidneys, without any structural changes typical for tumour mass presence).
Though spread of the primary tumour to the kidney is not uncommon, involvement severe enough to impair renal function is unusual and occurs primarily with rapidly growing haematologic malignancies; diagnosis is being established by renal biopsy only rarely.