What is waldenstrom macroglobulinemia (WM) and does it cause AKI?
WM is an IgM monoclonal-protein-secreting lymphoid and plasma cell malignancy. It usually manifests with anemia and fatigue, but it also may cause constitutional symptoms of fever, weight loss, and sweats; organ involvement with hepatosplenomegaly and lymphadenopathy; peripheral neuropathy; and features of hyperviscosity and cryoglobulinemia (rash). The diagnosis requires a monoclonal IgM protein and a bone marrow with >10% lymphoplasmacytic cell infiltration. Usually, the FLC component is kappa only, and urinary kappa LCs can be found in around 70% of cases.
4 Interesting Facts of Waldenstrom Macroglobulinemia
- A lymphoplasmacytic lymphoma with IgM monoclonal protein secretion
- Most common presentation is nasal or gingival bleeding (which is not typically observed in multiple myeloma)
- A characteristic clinical finding is macroglossia
- Differentiated from multiple myeloma by findings on bone marrow biopsy: the presence of IgM monoclonal protein associated with 10% or more clonal lymphoplasmacytic cells in bone marrow confirms the diagnosis
- For cases that are difficult to interpret, it is recommended to ascertain mutational status of a highly recurrent somatic mutation involving MYD88 (myeloid differentiation primary response 88), which is observed in almost all patients with Waldenström macroglobulinemia (ie, more than 90%)
Does Waldenstrom Macroglobulinemia cause AKI?
Kidney involvement with WM is uncommon and classic myeloma cast nephropathy is rare. Kidney involvement is glomerular and presents with hematuria/proteinuria, impaired kidney function, and rarely nephrotic syndrome. Histologically it takes the form of an immune-mediated glomerulonephritis with IgM deposition and/or features of cryoglobulinemia with intraglomerular thrombi. Treatment is delayed until patients develop significant end-organ damage or symptoms. Plasma exchange, rituximab, alkylating agents (chlorambucil), and the purine nucleoside analogues (fludarabine, cladribine) alone or in combination can be used.