Acute tumour lysis syndrome with no evidence of tumour load.

Acute tumour lysis syndrome (ATLS) is a well-recognised complication of the treatment of a variety of malignant disorders in which a large mass of disease is obvious. ATLS may, however, occur even in the absence of bulk disease. We present two cases which, together with a review of previously reported cases, suggest that a cause of this rare phenomenon is primary renal lymphoma which subsequently develops into the leukaemic phase. This is supported by the observation that some bone marrow aspirates which are normal at the time of ATLS have shortly afterwards demonstrated lymphoblasts. Renal biopsy may not exclude primary lymphoma of the kidney. In excluding lymphoproliferative disease in the differential diagnosis of acute hyperuricaemia, the importance not only of bone marrow examination but of exhaustive investigation of the kidneys is stressed.