IgD lambda multiple myeloma causing hyperammonaemia with possibly reduced ammonium excretion.

A man in his 70s presented with impaired consciousness due to hyperammonaemia while investigating multiple tumours in his brain, chest, spine and right adrenal gland. He did not have any disorders causing hyperammonaemia, such as liver dysfunction, urea-producing bacterial infection or any medications interfering with ammonium metabolism. Blood and urine tests in addition to tumour biopsy specimens confirmed immunoglobulin D lambda multiple myeloma. His general status responded to chemotherapy using bortezomib, dexamethasone and daratumumab, and he subsequently regained full consciousness and a normalised serum ammonia level. He, unfortunately, died of refractory multiple myeloma with hyperammonaemia. The autopsy specimen revealed lambda light-chain deposits in the distal tubule epithelium with cast precipitation and intact liver cells. Urine osmolality gap analysis suggested possibly reduced urinary ammonium excretion, but further investigation is necessary to elucidate the significance of pathological renal characteristics in multiple myeloma with hyperammonaemia.

Involvement of neutrophil extracellular traps in the pathogenesis of glomerulonephritis in a case of systemic lupus erythematosus and antineutrophil cytoplasmic antibody-associated vasculitis overlap syndrome.

Systemic lupus erythematosus (SLE) and antineutrophil cytoplasmic antibody-associated vasculitis (AAV) are autoimmune diseases that often cause rapidly progressive glomerulonephritis, with neutrophil extracellular traps (NETs) involved in their pathogenesis. However, the involvement of NETs in the renal damage caused by SLE/AAV overlap syndrome has not been clarified yet. In this study, we detected renal deposition of NETs in a patient with SLE/AAV overlap syndrome. In addition, a significantly increased level of NET-inducing activity was observed in the patient's serum, which improved with treatment. On the other hand, a markedly lower level of NET degradation was observed in the patient's serum as compared to healthy subjects' sera, without any posttreatment changes. These findings suggest that NETs may play a role in the pathogenesis of renal injury associated with SLE/AAV overlap syndrome.