Differential diagnosis between bone relapse of breast cancer and lambda light chain multiple myeloma: role of the clinical biochemist.

PURPOSE: The integration of expertise between oncologist and clinical biochemist for the monitoring and diagnosis of plasma cell dyscrasia is crucial. In some cases, medical laboratory scientists can provide an original contribution using the appropriate techniques to arrive at a diagnosis.

METHODS

We report a case of 67-year-old woman who was admitted to our hospital for bone pain. Imaging studies showed multiple diffuse bone lytic lesions, and a laboratory screen revealed anemia and altered creatinemia; serum capillary zone electrophoresis confirmed a monoclonal peak in the γ-zone that had been known since 2011, typed as immunoglobulin G kappa by immunosubtraction electrophoresis. The patient had undergone surgery for breast cancer in 2013, and based on her clinical history, the oncologist suspected the presence of bone metastases from the breast cancer and opted for relative therapy. Immunosubtraction, however, showed a very small reduction in lambda free light chains in the beta zone, but it was difficult to establish if was a monoclonal component, and consequently additional tests were performed.

DISCUSSION: A monoclonal component composed of only lambda free light chains was evidenced. This result in association with multiple diffuse bone lytic lesions observed led us to suspect multiple myeloma and not bone metastases from the breast cancer. Based on these observations, we encouraged the oncologist to conduct an osteomedullary biopsy, allowing us to make a diagnosis of low-grade stage II lambda light chain multiple myeloma.

CONCLUSION

In this report, we show how the expertise of the clinical biochemist was instrumental in solving this case.