抗黒色腫分化関連遺伝子5抗体陽性皮膚筋炎における致死的かつ広範な多臓器出血．剖検例の報告

Fatal and extensive multiorgan hemorrhages in anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: An autopsy case report.

• Tsuyoshi Watanabe
• Naoho Takizawa
• Toru Nagasaka
• Yoshihiro Nakamura
• Hiroki Ikai
• Mari Yamamoto
• Yukari Murai
• Koji Takasugi
• Waka Yokoyama-Kokuryo
• Yoshiro Fujita

抄録

はじめに:

抗黒色腫分化関連遺伝子5抗体（抗MDA5 Ab）は、皮膚筋炎（DM）に関連する自己抗原です。抗MDA5 Ab陽性のDM患者は、臨床的に筋炎性皮膚筋炎（CADM）を呈し、急速に進行する間質性肺疾患（RPILD）を発症することが多い。抗MDA5抗体陽性DM患者は，早期発見と強力な免疫抑制剤の併用療法を行っても予後不良である。本症例では，抗MDA5 Ab陽性DM患者にRPILDを発症し，肺標本にびまん性肺胞損傷（DAD）パターニングを認め，多臓器に広範囲の出血を認めた稀な剖検例を紹介する。

INTRODUCTION: Anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab) is an autoantigen associated with dermatomyositis (DM). Anti-MDA5 Ab-positive DM patients frequently exhibit clinically amyopathic dermatomyositis (CADM), and develop rapidly progressive interstitial lung disease (RPILD). Even with early detection and potent combination immunosuppressive therapy, anti-MDA5 Ab-positive DM patients have a poor prognosis. In the present case report, we present a rare autopsy case of a patient with anti-MDA5 Ab DM with RPILD who exhibited diffuse alveolar damage (DAD) patterning in lung specimens, and extensive hemorrhages in multiple organs.

患者の悩み:

細菌性肺炎で入院した82歳の日本人男性は，皮膚症状（力学的手，潰瘍性掌蹠丘疹，鞭毛状紅斑），筋炎，間質性肺炎，抗MDA5 Ab価の上昇から抗MDA5 Ab陽性DMと診断された．

PATIENT CONCERNS: An 82-year-old Japanese man admitted with bacterial pneumonia was subsequently diagnosed with anti-MDA5 Ab-positive DM based on skin manifestations (mechanic's hand, ulcerated palmar papules, and flagellate erythema), myositis, interstitial pneumonia, and elevation of anti-MDA5 Ab titer.

診断:

RPILDを合併した抗MDA5 Ab DMと診断された．

DIAGNOSIS: The patient was diagnosed with anti-MDA5 Ab DM, complicated with RPILD.

インターベンション:

患者は、メチルプレドニゾロンを1,000"Zs_200A"mgで3日間パルス投与した後、プレドニゾロンを60"Zs_200A"mg/日で投与し、シクロホスファミド（IVCY）を1,000"Zs_200A"mgでパルス投与し、タクロリムスを6"Zs_200A"mg/日で経口投与するという強力な免疫抑制療法を受けた。その後、免疫グロブリン（IVIG）を400"Zs_200A"mg/kg/dを5日間静注した。

INTERVENTIONS: The patient received potent immunosuppressive therapy consisting of pulse methylpredonisolone at a dose of 1000 mg for 3 days, followed by prednisolone at 60 mg/d, a 1000 mg pulse of intravenous cyclophosphamide (IVCY), and oral tacrolimus at 6 mg/d. Intravenous immunoglobulin (IVIG) at a dose of 400 mg/kg/d for 5 days was subsequently administered.

アウトカム:

3重の免疫抑制療法とIVIG投与にもかかわらず、患者の呼吸状態は悪化し、入院後12日目に呼吸不全で死亡した。剖検の結果、肺DADと左腸骨筋、胃・腸管粘膜、脾臓、左副腎などの多臓器出血を認めた。

OUTCOMES: Despite triple immunosuppressive therapy and IVIG, the patients' respiratory status deteriorated, and the patient died of respiratory failure on the twelfth day after admission. An autopsy revealed pulmonary DAD and multiorgan hemorrhages, including the left iliopsoas muscle, gastric and bowl mucosa, spleen, and left adrenal gland.

レッスン:

抗MDA5 Ab DM患者では多臓器出血が致命的な合併症となる可能性がある

LESSONS: Multiorgan hemorrhages may be a fatal complication in anti-MDA5 Ab DM patients.