Crystalline κ-light-chain proximal tubulopathy in Waldenström macroglobulinemia with an IgA nephropathy pattern: a case report and systematic review.

What was studied

This paper reports one case of a rare kidney problem in Waldenström macroglobulinemia. The problem is called light-chain proximal tubulopathy. The patient was a 65-year-old man. He had 4 years of blood and protein in his urine. His kidney function got worse over time. The authors also reviewed earlier cases in the medical papers.

What they found

An early blood test for MPO-ANCA was strongly positive. This raised concern for vasculitis. A repeat test showed only a modest rise. A kidney biopsy showed crystals in kidney tube cells. It also showed an IgA nephropathy pattern. It did not show active vasculitis damage. Bone marrow tests showed Waldenström disease with a MYD88-L265P change. Treatment was ibrutinib, then zanubrutinib. Bortezomib-dexamethasone was added for a time. This gave a lasting blood response. Kidney function stayed stable over 49 months.

What it means for patients

The authors say the case widens the range of kidney disease seen in Waldenström macroglobulinemia. They say crystal tube damage is a rare lesion tied to the abnormal clone. They say kidney tissue and blood tests should be read together.

Why it is not certain yet

This is one case plus a small review. The authors say crystal-storing histiocytosis was raised but not confirmed. The odd ANCA result was thought likely to reflect assay reactivity. It was not proven. The review found few earlier cases.

Source

Crystalline κ-light-chain proximal tubulopathy in Waldenström macroglobulinemia with an IgA nephropathy pattern: a case report and systematic review.

We restate facts from the source record in our own words. The original wording belongs to its publisher.