Anti-MDA5 Antibody-positive Dermatomyositis with Rapidly Progressive Interstitial Pneumonia Presenting with Nephrotic Syndrome during Treatment with Corticosteroids and Cyclosporine.

A 50-year-old Japanese woman with anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 antibody)-positive dermatomyositis presenting with rapidly progressive interstitial pneumonia was treated with corticosteroids and cyclosporine. She developed nephrotic syndrome during the treatment regimen with corticosteroids and cyclosporine. A kidney biopsy revealed a thrombotic microangiopathy (TMA) glomerular lesion. Anti-MDA5 antibody-positive dermatomyositis is prone to severe interstitial lung disease (ILD) and is often exacerbated and refractory to treatment. Renal symptoms might be due to TMA of the kidney, and this may be a sign that more intensive treatment is needed. Patients sometimes develop acute kidney injury, which may be due to the TMA.

Remission of light chain proximal tubulopathy in IgG λ-type multiple myeloma by lenalidomide and dexamethasone therapy.

Light chain proximal tubulopathy is a rare manifestation of monoclonal gammopathy. A 73-year-old Japanese woman was noted to have urinary protein and hypertension on health examination and visited the regional clinic. She was noted to have IgG λ M protein and suspected of multiple myeloma. She was referred to us with massive proteinuria (7.5 g/g creatinine) and Bence Jones proteinuria without renal dysfunction. A renal biopsy revealed no glomerular abnormalities, but a tubular cast was observed partially in tubules without tubular atrophy or a crystalline structure. Direct Fast Scarlet staining was absent both in glomerulus and vascular wall. Immunofluorescence revealed λ light chain (LC) staining in the proximal tubules. Electron microscopy revealed nonspecific findings including increased lysosomes with irregular contours and mottled appearance. A bone marrow biopsy revealed plasma cell proliferation (35%) and multiple myeloma immunoglobulin G λ type. She showed progressive anemia and decrease of eGFR with elevated level of urinary ß-2 microglobulin. She was treated with lenalidomide + dexamethasone (Ld). With Ld therapy, she achieved hematologic and nephrologic remission reducing the free LC, λ/κ ratio, urinary protein level, and urinary ß-2 microglobulin level.

Acquired Factor V Inhibitors in a Patient with End-stage Renal Disease.

We report a case of acquired factor V inhibitors (AFVIs) in a patient with end-stage renal disease receiving warfarin therapy for atrial fibrillation. A 72-year-old Japanese man was admitted to our hospital complaining of tarry stools and abdominal pain. The laboratory findings revealed eosinophilia (52.1%), prolonged activated partial thromboplastin time (APTT) (98 s), PT (84 s), a factor V (FV) activity of <3%, and an FV inhibitor level of 6 Bethesda units/mL. After administration of prednisolone was started, his coagulation findings improved. However, his renal failure progressed, and he ultimately required chronic hemodialysis. This is the first case of AFVIs in a patient starting hemodialysis for end-stage renal disease.

Myeloperoxidase Antineutrophil Cytoplasmic Antibody (MPO-ANCA) Associated Crescentic and Necrotizing Glomerulonephritis (GN) with Membranoproliferative GN Features.

A 77-year-old man presented with a fever, non-productive cough, and edema formation. A laboratory analysis showed an elevated creatinine level (2.5 mg/dL), a high titer of myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA) (99 U/mL), positive reaction for antinuclear antibody (×320), hematuria, and massive proteinuria (3.33 g/day). A renal biopsy revealed crescentic and necrotizing glomerulonephritis (GN) with membranoproliferative GN features [double contour appearance of the glomerular basement membrane, granular deposition of immunoglobulin (Ig) G, IgM, and C3 along the capillary wall, subendothelial and subepithelial deposits with mesangial interposition]. A potential relationship between MPO-ANCA associated GN and membranoproliferative GN is discussed.