Primary renal lymphoma does exist: case report and review of the literature.

Primary renal lymphoma (PRL) is a controversial and rare disease and there is still no agreement on its existence. Many cases have been reported in the literature, but clear diagnostic criteria have not yet been established. Most of the reported cases are questionable because of incomplete staging or the presence of extrarenal disease. Here we report a new case and a review of the literature based on a critical examination of the diagnostic procedure. Thus, probably only 29 cases, ours included, should be recognized as PRL, because only these cases fulfil the three diagnostic criteria and underwent complete diagnostic screening, including renal biopsy, bone marrow biopsy and thoraco-abdominal computerised tomography (CT).