PMC5313426_01
The light microscopy findings of the kidney biopsy specimen. (A) Nodular glomerulosclerosis was observed in the glomeruli, PAS x400. (B) Massive deposition and a nodular pattern in glomeruli, PAS x200. (C) Negative Congo red staining, Congo red x50. (D) Negative green birefringence under polarized light with Congo red staining, Congo red x50.
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Kidney biopsy at the previous hospital demonstrated nodular glomerulosclerosis in all 29 glomeruli examined (Fig. 1A and B). Congo red staining was negative at the previous hospital; there was very weak positivity and no characteristic green birefringence under polarized light (Fig. 1C and D).
The electron microscopy findings. Randomly arranged fibrillar structures with a width of 7-13 nm were observed in the subendothelial and mesangial areas. Bar, 200 nm.
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Electron microscopy showed randomly arranged fibrillar structures with a width of 7-13 nm in the subendothelial and mesangial areas (Fig. 2); however, electron-dense deposits were not observed.
Immunofluorescence and immunohistochemical studies demonstrated no significant deposition of kappa and lambda light chains. (A) The non-specific findings in the nodular lesions, kappa chain immunofluorescence study, x200. (B) Small spots were observed in the subendothelial spaces. There were non-specific findings in the nodular lesions in the lambda chain immunofluorescence study, x200. (C) Negative findings in the nodular lesions, kappa chain immunohistochemical study, x200. (D) Negative findings in the nodular lesions, lambda chain immunohistochemical study, x200.
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Immunofluorescence and immunohistochemical studies demonstrated no significant deposition of immunoglobulin heavy or light chains (Fig. 3) or fibronectin.
The results of laser micro-dissection and liquid chromatography tandem mass spectrometry (LC-MS/MS). The kappa chain constant region (21.37%) and kappa chain III variable region (13.8%) were the predominant components of the nodular lesion depositions (highlighted in yellow). The amyloid P component was 2.14%, which was less than serum albumin (3.33%).
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Laser micro-dissection and LC-MS/MS of the nodular glomerular lesions revealed substantial deposition of the kappa chain constant region and kappa chain III variable region (Fig. 4).
The clinical course. Dex therapy and Thal-Dex therapy decreased the serum levels of free kappa light chain from 147 to 38 mg/L, and his proteinuria resolved (less than 0.3 g/day). There was no progressive decline in the kidney function, with serum creatinine levels stable around 4.0 mg/dL for 3 years.
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Thal-Dex therapy was effective in this patient; the serum levels of free kappa light chain decreased to 38 mg/L, his proteinuria resolved (less than 0.3 g/day), and there was no progressive decline in his kidney function, with serum creatinine levels stable around 4.0 mg/dL for 3 years (Fig. 5).