The Role of Bone Marrow Biopsy Evaluation in the Workup for Monoclonal Gammopathy of Renal Significance: A Diagnosis of Exclusion

Arch Pathol Lab Med. 2024 Mar 1;148(3):e57-e62. doi: 10.5858/arpa.2022-0342-OA.


Context.—: Monoclonal gammopathy of renal significance (MGRS) is a relatively new concept for patients with renal monoclonal protein deposition (RMPD) (except monoclonal cast nephropathy) and has been used as a reason for nephrologists to obtain a bone marrow biopsy (BMB). It takes a team of pathologists and clinicians to determine when RMPD at our institution can be defined as MGRS.

Objective.—: To identify the proportion of various subtypes of tentative MGRS diagnosed by renal biopsy that can be confirmed as final MGRS after BMB.

Design.—: One hundred thirty kidney biopsies with variants of RMPD were identified during the past 10 years. Biopsy cases with known myeloma, B-cell lymphoma, or monoclonal cast nephropathy were separated as a heavy-burden group. The remaining biopsies with RMPD were considered tentative MGRS. Their BMB and clinical indices were further analyzed to determine the final percentage of MGRS diagnoses.

Results.—: Among the 130 renal paraprotein deposition cases, 44 (33.8%) were categorized as the heavy-burden group. In the remaining 86 cases, 33 (38.4%) with subsequent identification of myeloma (>10% of monoclonal plasma cells) or lymphoma in BMB were further considered as heavy-burden cases. Eighteen cases (18 of 86; 20.9%) did not receive follow-up BMB; thus, no further analysis was performed. BMBs diagnosed as either nonmalignant (no plasma cells; 8 of 86 cases; 9.3%) or premalignant (<10% plasma cells; 27 of 86 cases; 31.4%) were confirmed to be final MGRS (35 of 86; 40.7%).

Conclusions.—: The data indicate that BMB is an important element in the confirmation of MGRS.

MeSH terms

  • Biopsy
  • Bone Marrow / pathology
  • Humans
  • Kidney / pathology
  • Kidney Diseases* / diagnosis
  • Kidney Diseases* / etiology
  • Kidney Diseases* / pathology
  • Monoclonal Gammopathy of Undetermined Significance* / diagnosis
  • Monoclonal Gammopathy of Undetermined Significance* / pathology
  • Multiple Myeloma* / diagnosis
  • Multiple Myeloma* / pathology
  • Paraproteinemias* / diagnosis