Kidney Week

Abstract: PO1755

A Case of Microscopic Polyangiitis Accompanied by Refractory Immune Thrombocytopenic Purpura

Session Information

• Glomerular Diseases: Vasculitis and TMA
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Report

• 1202 Glomerular Diseases: Immunology and Inflammation

Authors

• Muto, Masahiro, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Masahiro Muto,

• Suzuki, Hitoshi, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Hitoshi Suzuki,

• Kanaguchi, Yasuhiko, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Yasuhiko Kanaguchi,

• Yanagawa, Hiroyuki, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Hiroyuki Yanagawa,

• Kihara, Masao, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Masao Kihara,

• Ueda, Seiji, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Seiji Ueda,

• Gohda, Tomohito, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Tomohito Gohda,

• Suzuki, Yusuke, Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo, Japan

Yusuke Suzuki,

Introduction

Microscopic polyangiitis (MPA) is an idiopathic autoimmune disease characterized by systemic vasculitis that predominantly affects the small blood vessels and is mediated by the presence of antineutrophil cytoplasmic autoantibodies (ANCA). Immune thrombocytopenic purpura (ITP) is also an autoimmune disease characterized by autoantibody induced platelet destruction and reduced platelet production, leading to low blood platelet count. Secondary ITP is defined as an ITP induced by other diseases including autoimmune disorders. Here we present a rare case of a patient who developed ITP just after treatment with steroids for MPA with rapidly progressive glomerulonephritis (RPGN).

Case Description

66-year-old female was hospitalized due to microscopic hematuria, proteinuria, elevated serum creatinine (2.8mg/dL) and high Myeloperoxidase-ANCA (MPO-ANCA) titres (94.1U/ml). We performed a renal biopsy that revealed pauci immune crescentic glomerulonephritis. After the definitive diagnosis of MPA, the patient was treated with intravenous corticosteroids and oral prednisone (0.8mg/kg). Although serum creatinine subsequently improved to 1.6mg/dl, the peripheral platelet count was rapidly reduced from 20×10⁹/L to 2×10⁹/L after a week treatment with steroids. She was frequently treated with platelet transfusion. Bone marrow examination revealed normal morphology of all the cell lines, with increased megakaryocytes. Based on the clinical findings, we diagnosed as ITP. Then, the patient received rituximab followed by thrombopoietin-receptor agonists eltrombopag. After a week of treatment with oral eltrombopag at 25mg daily, the platelet count increased from 0.5×10⁹/L to 4×10⁹/L. After six weeks from initiation of eltrombopag, her platelet count remains >3×10⁹/L, and she has not shown any signs of bleeding or hemorrhage. MPO-ANCA titres reduced to 1.3U/ml.

Discussion

It is a novel case of MPA with RPGN accompanied by ITP. It was recently recognized that diversity existed in both pathogenesis and clinical characteristics in patients with ITP. Present case showed the possibility for an association of pathological mediator for both diseases. Although further studies are needed to confirm this idea, present findings provide clues for our understanding of this association for a better management of these diseases.