COVID-19に続発した免疫性血小板減少症紫斑病

Immune Thrombocytopenia Purpura Secondary to COVID-19.

• Joseph Bennett
• Christopher Brown
• Michael Rouse
• Marc Hoffmann
• Zhan Ye

抄録

本態性高血圧症，高脂血症，季節性アレルギー，慢性腰痛の既往歴を有する73歳女性が頭痛，発熱，倦怠感，全身痛，息切れ，下痢を訴えて来院した．初診時の全血球数は白血球減少が顕著で，リンパ球絶対数は0.60K/μL，重度の血小板減少（血小板数<3K/μL）であった．鼻咽頭スワブポリメラーゼ連鎖反応（PCR）検査でCOVID-19を検査したところ陽性であった。その他の検査では、Dダイマー、C反応性蛋白、フィブリノーゲン、乳酸脱水素酵素の上昇が認められた。ビタミンB12、葉酸値は正常であった。末梢塗抹標本では、血小板減少症以外の組織球や血液学的異常は認められなかった。血小板数に改善は見られなかったが、1単位の血小板を輸血した。フィブリノゲン値は458mg/dLと正常範囲であった．免疫性血小板減少症紫斑病（ITP）を疑い，免疫グロブリン（IVIG）を1g/kg/日の用量で2回投与した。退院4日目には血小板数が105K/μLまで回復し、治療効果は顕著であったが、5日目には症状は完全に消失し、血小板数は146K/μLとなった。退院後28日目に血液内科を受診し、血小板数は8K/xB5;Lであった。反復鼻咽頭スワブPCR COVID検査は陰性であったため、IVIGとパルスデキサメタゾンによる治療を受けた。

A 73-year-old female with past medical history of essential hypertension, hyperlipidemia, seasonal allergies, and chronic back pain presented to the hospital with complaints of headaches, fevers, fatigue, generalized body aches, shortness of breath, and diarrhea. Initial complete blood count was remarkable for leukopenia with an absolute lymph count of 0.60 K/µL and severe thrombocytopenia (platelet count < 3 K/µL). She was tested for COVID-19 via nasopharyngeal swab polymerase chain reaction (PCR) testing and found positive. Additional labs showed an elevated D-dimer, C-reactive protein, fibrinogen, and lactate dehydrogenase. Vitamin B12 and folate levels were obtained and found to be normal. Peripheral smear showed no schistocytes or additional hematologic abnormalities apart from thrombocytopenia. The patient was transfused one unit of platelets with no improvement in platelet count. Fibrinogen count was obtained and found in normal range at 458 mg/dL. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and international normalized ratio (INR) were all found to be normal. Immune thrombocytopenia purpura (ITP) was suspected and intravenous immunoglobulin (IVIG) was administered at a dose of 1 g/kg/day for two doses. By day 4, the patient had marked response to treatment with platelet recovery to 105 K/µL and subsequently discharged by day 5 with complete resolution of symptoms and platelet count of 146 K/µL. Twenty-eight days after discharge, she presented to hematology clinic with platelet count of 8 K/µL. Repeat nasopharyngeal swab PCR COVID testing was negative and she was treated with IVIG and pulse dexamethasone with prompt response, confirming suspicion of underlying, undiagnosed ITP prior to COVID infection.

Copyright © 2020, Bennett et al.