Crystal nephropathy: a variant form of myeloma kidney--a case report and review of the literature.

Cast nephropathy is the most common form of myeloma kidney, and also one of the major determinants of a patient's prognosis. We experienced a case of multiple myeloma with acute renal failure that was associated with massive crystal deposition in kidney and bone marrow. Large crystal formation in myeloma kidney is a rare pathological finding in renal biopsies. In the literature, most of the cases with multiple myeloma with extracellular crystal deposition often have a rapidly progressive course with a poor prognosis. Ball et al. [1993] suggested that this type of extracellular crystal deposition be designated as "crystalglobulinemia syndrome". The characteristics of the clinical and histopathological features, rapid progression and poor outcome, and crystal formation in the tubules found in the present case and in those previously reported, support the proposal of a new concept of "crystal nephropathy".