Monoclonal gammopathy of renal significance from a hematologic perspective.

Monoclonal gammopathy of renal significance (MGRS) represents a clinical entity where clonal plasma or B-cell proliferative disorders secrete a monoclonal protein that leads to renal damage without meeting the diagnostic criteria for overt hematologic malignancies such as multiple myeloma or lymphoma. The diagnosis typically requires a kidney biopsy. MGRS subtypes are divided into 3 groups based on their pathologic findings: organized deposits, nonorganized deposits, and absence of immune deposits. Identifying the underlying clonal population of plasma cells or B cells is important to guide therapy. The standard of care for upfront treatment of light chain amyloidosis is daratumumab, cyclophosphamide, bortezomib, and dexamethasone. For other types of MGRS, the treatment depends on the underlying clone or the identified monoclonal protein. While light chain amyloidosis has validated response criteria, there are no uniform response criteria for other MGRS subtypes. Renal transplantation has been historically underutilized and represents a potentially transformative intervention in carefully selected patients who achieve good disease control using clone-directed therapy.