A case of malignancy-associated cryoglobulinemia.

We present a case of type 1 cryoglobulinemia with an underlying hematological malignancy. Unusually, the entire unifying diagnosis was made on the basis of the renal biopsy. Initially, serum cryoglobulin was not identified; repeat samples were positive. It is important to note that there is a significant false-negative rate with laboratory testing for cryoglobulin, due, at least in part, to the specific conditions required for collection and processing. With that in mind, in all cases with strong clinical or histological evidence of cryoglobulin but negative testing, carefully repeated samples should be sent.