Hiroki Mizuno

Renal histology in a patient with TAFRO Syndrome: A case report

An 84-year-old Japanese man was admitted due to anasarca, thrombocytopenia, systemic inflammation, and progressive renal insufficiency, resistance to diuretics, glucocorticoid therapy, and plasma exchange. Renal biopsy showed diffuse endocapillary proliferation and mesangiolysis without any immune deposits. Tocilizumab suppressed systemic inflammation, resulting in improvement of anasarca and renal dysfunction, but thrombocytopenia persisted and platelet-associated IgG antibody was elevated. Although romiplostim was effective for thrombocytopenia, the patient died of aspiration pneumonia after cerebral hemorrhage. Autopsy showed hyaline vascular-type Castleman disease-like lymphadenopathy and reticulin myelofibrosis with an increase of megakaryocytes. Renal finding showed that endocapillary injury improved, and collapsed glomeruli were noted. This patient fitted the criteria for TAFRO (thrombocytopenia [T], anasarca [A], fever [F], reticulin myelofibrosis [R], and organomegaly [O]) syndrome. The clinical course suggests that 2 factors, including overproduction of interleukin 6 and autoimmune-mediated thrombocytopenia via thrombopoietin receptor, may have contributed to the pathogenesis of TAFRO syndrome in this patient.

Sequential renal biopsy in a patient with lupus nephritis and fingerprint deposits: a case report

Abstract We report a 38-year-old Japanese man in whom lupus membranous nephropathy was diagnosed by renal biopsy. Steroid therapy was initiated, followed by cyclophosphamide and calcineurin inhibitors. Although serum markers for the activity of lupus nephritis (LN) showed improvement, his renal function gradually declined. During this period, renal biopsy was repeated three times whenever proteinuria increased, revealing progression of lupus membranous nephropathy with an increase of epithelial immune deposits. Electron microscopy of the first biopsy specimen did not clearly show subepithelial fingerprint deposits, but these structures were better-defined at the second biopsy. The number of bands in the deposits was larger at the third biopsy and increased to a maximum of 25 at the fourth biopsy. These findings indicate that fingerprint deposits may be related to chronic change or disease activity of lupus membranous nephropathy, but the changes of these deposits were not consistent with those of serum markers of LN disease activity.

Renal-limited Cryoglobulinemic Vasculitis: Two Case Reports

Cryoglobulinemic vasculitis (CV) presents with systemic manifestations, including renal disease, arthritis, peripheral neuropathy, and muscle weakness. We encountered two patients who developed severe nephrotic range proteinuria; however, extrarenal manifestations were not noted during the clinical course. A renal biopsy revealed typical membranoproliferative glomerulonephritis (MPGN) with huge thrombus-like endothelial deposits and predominant IgM positivity, but electron microscopy did not reveal any definite microtubules. Immunosuppressive therapy and plasmapheresis were only partially effective, and the improvement was not durable. Biological therapy with rituximab (RTX) had no effect. Renal-limited CV should be recognized as a subset of essential CV.

Transcatheter Arterial Embolization Therapy for Huge Renal Cysts: Two Case Reports

We encountered 2 patients with symptomatic huge simple renal cysts. In case 1, 4,000 mL of cyst fluid was drained via a catheter, but intracystic bleeding occurred immediately afterwards. Transcatheter arterial embolization (TAE) was performed, after which the bleeding stopped, and cyst drainage was repeated successfully. After 2 years, the total cyst volume was reduced from 11,775 mL to 75.4 mL. In case 2, TAE was performed prophylactically before drainage. Subsequently, 9,400 mL of fluid was removed from multiple cysts. After 1 year, the total cyst volume was reduced from 9,215 mL to 633 mL without bleeding. Based on these 2 cases, prophylactic TAE before drainage may be useful in patients with huge renal cysts.

Tolvaptan for Primary Aldosteronism and Autosomal Dominant Polycystic Kidney Disease: A Case Report

A 59-year-old Japanese woman was admitted for evaluation of muscle weakness. Autosomal dominant polycystic kidney disease had been diagnosed at the age of 47 years, followed by primary aldosteronism at 53 years. At the age of 58, tolvaptan was started (60 mg/day) to treat her renal disease. After 8 months of tolvaptan therapy, hypokalemia-related muscle weakness became prominent, and hypertension became refractory. Finally, treatment with low-dose tolvaptan (30 mg/day) and high-dose spironolactone (100 mg/day) normalized serum potassium and the blood pressure. Tolvaptan can induce urinary excretion of potassium in patients with primary aldosteronism, and possible mechanisms are discussed.

Everolimus Reduces the Size of Tuberous Sclerosis Complex-Related Huge Renal Angiomyolipomas Exceeding 20 cm in the Longest Diameter

We evaluated the efficacy of everolimus in 3 patients who had huge renal angiomyolipomas associated with tuberous sclerosis complex. Two patients with large lipid-rich angiomyolipomas had a history of renal transarterial embolization for renal bleeding, but the effect had only been temporary and the embolized kidneys had continued to enlarge. In case 1, case 2, and case 3, total renal volume was respectively 3,891, 4,035, and 1,179 cm3 before administration of everolimus, decreasing to 3,016 (77%), 3,043 (75%), and 1,051 (89%) cm3 after 1 year of everolimus therapy and to 2,832 (73%), 3,209 (80%), and 1,102 (93%) cm3 after 3 years. New renal bleeding did not occur, but elevation of serum creatinine and urinary protein were noted in 2 patients. While previous reports have largely assessed the effect of everolimus for angiomyolipomas of < 10 cm in the longest diameter, our findings suggest that this drug might also be effective for huge lesions of > 20 cm in diameter. However, total renal volume still exceeds 2,000 cm3 in 2 of our patients, suggesting limited size reduction of lipid-rich angiomyolipomas. In addition, occurrence of everolimus-related nephropathy needs to be monitored carefully.

Long-term Low-density Lipoprotein Apheresis in a Patient with Refractory Idiopathic Membranous Glomerulonephritis

A 61-year-old Japanese man developed nephrotic syndrome (NS) due to idiopathic membranous glomerulonephritis (MGN). He received immunosuppressive therapy for two years, including prednisolone, cyclophosphamide, and cyclosporine A, but the NS persisted. Low-density lipoprotein apheresis (LDL-A) was initiated at a frequency of twice a month and continued for 9 years (203 sessions in total). His proteinuria reduced to less than 1 g daily after 9 years. LDL-A was stopped, and the NS has not relapsed for five years. This case suggests that long-term LDL-A therapy may be a treatment option for idiopathic MGN refractory to immunosuppressive therapy or short-term LDL-A.

Tolvaptan for the Treatment of Enlarged Polycystic Liver Disease

A 44-year-old Japanese woman with autosomal dominant polycystic kidney disease was admitted to our hospital for evaluation of abdominal distension. Her eGFR was 53.7 mL/min/1.73 m2. Total kidney volume was 2,614 mL. Tolvaptan (60 mg/day) was started to treat renal involvement. The patient’s abdominal fullness began to improve and liver volume, indicating advanced polycystic liver disease (PLD), decreased from 9,750 mL to 8,345 mL after 17 months of tolvaptan treatment, though there was no significant change in kidney volume. This case indicates that tolvaptan may be a therapeutic option for hepatomegaly in patients with symptomatic PLD.

Sjögren Syndrome-Related Membranous Glomerulonephritis Progressing to Membranoproliferative Glomerulonephritis

We report a case of glomerulopathy in a 36-year-old Japanese woman with primary Sjögren syndrome (pSS). The first renal biopsy suggested membranous glomerulonephritis. However, repeat biopsy was performed after 16 years because of increased proteinuria, revealing membranoproliferative glomerulonephritis with mesangial deposits, subendothelial deposits, and subepithelial deposits. Immunofluorescent studies showed predominant deposition of IgG2 and IgG4. This patient was positive for antinuclear antibody and anti-SS-A antibody. Sicca syndrome was confirmed by a positive Schirmer test and positive Rose Bengal test. Therefore, pSS-related glomerulopathy was considered to be the most likely diagnosis.