Improvement of Light Chain Proximal Tubulopathy Without Crystals in IgGλ-type Monoclonal Gammopathy of Undetermined Significance using Bortezomib and Dexamethasone: A Case Report

Tomohisa Tsuyuki; Tadashi Uramatsu; Masatoshi Shimizu; Takuma Ishi; Kiyokazu Tsuji; Jun Nakashima; Eisuke Katafuti; Toshiyuki Nakayama; Noriko Uesugi; Kumiko Muta; Tomoya Nishino

doi:10.2169/internalmedicine.1835-23

This article has now been updated. Please use the final version.

Improvement of Light Chain Proximal Tubulopathy Without Crystals in IgGλ-type Monoclonal Gammopathy of Undetermined Significance using Bortezomib and Dexamethasone: A Case Report

Tomohisa Tsuyuki, Tadashi Uramatsu, Masatoshi Shimizu, Takuma Ishi, Kiyokazu Tsuji, Jun Nakashima, Eisuke Katafuti, Toshiyuki Nakayama, Noriko Uesugi, Kumiko Muta, Tomoya Nishino

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Keywords: light chain proximal tubulopathy without crystals, monoclonal gammopathy of renal significance, monoclonal gammopathy of undetermined significance, paraprotein-related kidney disease

JOURNAL OPEN ACCESS Advance online publication

Article ID: 1835-23

DOI https://doi.org/10.2169/internalmedicine.1835-23

The final version of this article is now available: Vol. 63 (2024), No. 5 pp. 693-698

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Abstract

A 70-year-old woman with acute kidney injury, a high serum creatinine level (3.91 mg/dL), and proteinuria (PCR 1.59 g/g Cr) was admitted. Serum IgG λ-type and urinary λ-type M proteins were observed. A bone marrow examination indicated monoclonal gammopathy of undetermined significance (MGUS). A renal biopsy showed distended proximal tubular cells, and immunofluorescence identified tissue positive for proximal tubular cell λ light chains. Electron microscopy identified fibril-like structures in the lysosomes. The patient was diagnosed with light chain proximal tubulopathy without crystals in IgG λ-type MGUS and treated with bortezomib and dexamethasone therapy, which improved her renal function.

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