Combined crystal-storing histiocytosis, light chain proximal tubulopathy, and light chain crystalline podocytopathy in a patient with multiple myeloma: a case report and literature review

Abstract

Background

Crystal-storing histiocytosis (CSH), light chain proximal tubulopathy (LCPT), and light chain crystalline podocytopathy (LCCP) are rare complications of multiple myeloma (MM) or monoclonal gammopathy of renal significance, and their diagnoses are challenging.

Case presentation

In this case, a 69-year-old Chinese woman presented with suspicious Fanconi syndrome with renal insufficiency. Immunofixation electrophoresis of both serum and urine revealed elevated immunoglobulin G kappa (IgGkappa) and kappa light chain. Bone marrow aspirate revealed 15% plasma cells with considerable cytoplasmic granular inclusions and needle-shaped crystals. Renal biopsy confirmed the final pathologic diagnosis of kappa-restricted CSH, combined LCPT and LCCP by immunoelectron microscopy. A number of special casts were present which could easily be misdiagnosed as light chain cast nephropathy. Immunofluorescence on frozen tissue presented false negative for kappa light chain, as ultimately proven by paraffin-embedded tissue after pronase digestion. MM and CSH were diagnosed, and two cycles of chemotherapy were given. The patient subsequently refused further chemotherapy, and her renal function remained relatively stable during a 2.5-year follow-up period.

Conclusions

In conclusion, we report a rare case of generalized kappa-restricted CSH involving bone marrow and kidney, combined with LCPT and LCCP, provide a comprehensive summary of renal CSH, and propose a new nomenclature of monoclonal immunoglobulin-induced crystalline nephrology. The presentation of monoclonal immunoglobulin and Fanconi syndrome should suggest the presence of monoclonal immunoglobulin-induced crystalline nephrology. Use of paraffin-embedded tissue after pronase digestion and immunoelectron microscopy is beneficial to improve the sensitivity of diagnosis.

Keywords:

• Crystal-storing histiocytosis
• multiple myeloma
• light chain proximal tubulopathy
• light chain crystalline podocytopathy
• monoclonal immunoglobulin-induced crystalline nephrology

Acknowledgments

The authors would like to thank our patient for allowing for her case to be presented.

Ethical approval

Ethical approval was obtained from the Ethics Committee of Peking University People’s Hospital, China, in accordance with the ethical guidelines of the 1975 Declaration of Helsinki (ethical approval number: 2021PHB309-001).

Consent form

Written informed consent was obtained from the patient. The patient has provided written informed consent for publication of this case and any accompanying images. A copy of the written consent is available for review by Editor-in-Chief of this journal. Written informed consent for publication was obtained from all participants.

Author contributions

Conceptualization: Li Zhu and Bao Dong. Supervision: Li Zhu, Lei Wang, Yu Yan, Bao Dong and Li Zuo. Writing – original draft: Li Zhu. Writing – review & editing: Yu Yan, Bao Dong and Li Zuo. Hongxia Shi, Lei Jiang and Wanzhong Zou provided good suggestions for study design and data collection. Xin Li and Chunying Shao helped in the collection of pathology results. The author(s) read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this study are included in this published article.

Additional information

Funding

Project (RDY2021-29) was supported by Peking University People’s Hospital Research and Development Funds. This work was supported by the National Natural Science Foundation of China (81000296).