Table 1.

Monoclonal Gammopathies of Renal Significance (MGRS)*.

Lesions associated with deposition of the paraprotein (fragment or whole immunoglobulin)

Light chain cast nephropathy** Light chain proximal tubulopathy, crystalline or non-crystalline subtypes (Cryo)crystaglobulin associated nephropathy Crystal-storing histiocytosis Immunoglobulin-related amyloidosis Monoclonal immunoglobulin deposition disease

Light chain deposition disease   Light and heavy chain deposition disease   Heavy chain deposition disease

7. Proliferative glomerulonephritis with monoclonal immunoglobulin deposits

8. Cryoglobulinemic glomerulonephritis (Type 1 cryoglobulins)

9. Monoclonal immunotactoid glomerulopathy/fibrillary glomerulonephritis***

Lesions not associated with paraprotein deposition

C3 glomerulopathy

C3 glomerulonephritis

Dense deposit disease

2. Thrombotic microangiopathy***

*Refers to specific kidney lesions in patients with paraproteins from B-lineage clones (B-cells, plasma cells, or lymphoplasmocytes) not satisfying criteria for frank malignancy (multiple myeloma, lymphoplasmocytic lymphoma, chronic lymphocytic leukemia, marginal zone lymphoma). The same lesions could be found in patients having such malignancies but are not referred to as MGRS in that situation.

**Rare in the absence of criteria for frank multiple myeloma (where it would be a treatment defining lesion), but possible in which case it would qualify as MGRS.

***Provisional association with paraprotein.