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The kidneys may be affected in a variety of ways in the plasma cell dyscrasias; all of the important lesions result from the accumulation/deposition of the paraprotein in some or all of the renal components (Table 33–1). The different abnormalities are determined by properties of the paraprotein rather than the patient response. The kidneys may be the only organ affected [the lesion known as Bence Jones (myeloma) cast nephropathy] or may be part of systemic processes (amyloidosis, monoclonal immunoglobulin deposition disease). A diagnosis of a plasma cell dyscrasia is not always known prior to the discovery of abnormal kidney function. The renal biopsy, performed to identify the responsible lesion, is not infrequently the initial indication of a plasma cell dyscrasia. Although multiple myeloma (MM) may be diagnosed, it is important to appreciate that some of the disorders discussed here may be associated with either a monoclonal gammopathy of uncertain significance (MGUS) or only a minor increase in bone marrow plasma cells. The clinical manifestations depend on the type of renal involvement, the renal tissue component affected, and whether only one or more of the lesions are present. The definition of the specific lesion is dependent on the tissue pathologic features, for the clinical and laboratory findings often do not readily allow for a specific diagnosis.
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Durie BG, Kyle RA, Belch A, Bensinger W, et al: Myeloma management guidelines: a consensus report from the Scientific Advisors of the International Myeloma Foundation. Hematol J 2003;4:379.
[PubMed: 14671610]
Herrera GA, Joseph L, Gu X, Hough A, Barlogie B: Renal pathologic spectrum in an autopsy series of patients with plasma cell dyscrasia. Arch Pathol Lab Med 2004;128:875.
[PubMed: 9740176]
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Essentials of Diagnosis
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- Heavy proteinuria.
- Renal insufficiency.
- Monoclonal free light chains (LCs) in serum or urine.
- Renal biopsy disclosing characteristic extracellular deposits.
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General Considerations
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A contemporary classification of systemic amyloidosis (AL), based on the nature of the amyloid protein that is deposited in tissue, is given in Table 33–2. Amyloidosis is a disorder of abnormal protein folding in which normally soluble proteins are deposited in tissues as fibrillar structures that disrupt organ function and produce disease. The proteins are folded into a β-pleated sheet form that results in a high affinity for Congo red ...