Reactivation of BK virus (BKV) remains a dreaded complication in immunosuppressed states. Conventionally, BKV is known as a cause for BKV-associated nephropathy and allograft dysfunction in kidney transplant recipients. However, emerging studies have shown its negative impact on native kidney function and patient survival in other transplants and its potential role in diseases such as cancer. Because BKV-associated nephropathy is driven by immunosuppression, reduction in the latter is a convenient standard of care. However, this strategy is risk prone due to the development of donor-specific antibodies affecting long-term allograft survival. Despite its pathogenic role, there is a distinct lack of effective anti-BKV therapeutics. This limitation combined with increased morbidity and health care cost of BKV-associated diseases add to the complexity of BKV management. While summarizing recent advances in the pathogenesis of BKV-associated nephropathy and its reactivation in other organ transplants, this review illustrates the limitations of current and emerging therapeutic options and provides a compelling argument for an effective targeted anti-BKV drug.

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Crystalcryoglobulinemia refers to the extracellular deposition of crystals in the systemic vasculature, leading to vascular injury, thrombosis, and occlusion. This entity is usually described as a complication of multiple myeloma, although it can also occur in the setting of a monoclonal gammopathy of renal significance. Synchronous presentation of a monoclonal gammopathy and renal cell carcinoma is rare. Hypothetically, as both neoplasms’ growth depends on certain cytokines such as interleukin-6, it is possible that cytokine production from one neoplasm may stimulate the growth of the other. In this report, we describe a case of crystalcryoglobulinemia in a patient with a monoclonal gammopathy of renal significance and concomitant renal cell carcinoma. Additionally, we performed a systematic review of the literature and analyzed data of 61 reported cases of crystalcryoglobulinemia and of 40 reported cases describing the association between multiple myeloma and renal cell carcinoma.