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Vol.61 No.4 contents | Japanese/English |
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- Case Report -
Polymyositis That Developed During Osimertinib Administration for Lung Adenocarcinoma
Shigehisa Kajikawa1, Yohei Okada2, Eisuke Fujishiro1, Jun-ichi Niwa2, Satoru Ito1, Akihito Kubo11Department of Respiratory Medicine and Allergology, 2Department of Neurology, Aichi Medical University Hospital, Japan
Background. Certain malignancies are known to occasionally occur in patients with polymyositis. Conversely, the occurrence of polymyositis during the treatment of lung cancer is rare. Case. We herein report a case of polymyositis that occurred during the treatment of lung adenocarcinoma with an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). A 58-year-old woman who was diagnosed with stage IV lung adenocarcinoma with an EGFR mutation (exon 19 deletion) received the EGFR-TKI osimertinib. During treatment, she experienced progressive pain in the proximal muscles. Laboratory findings revealed an increase in creatine kinase (CK) levels. Upon a further examination, she was diagnosed with polymyositis as a paraneoplastic syndrome. Systemic steroids, immunosuppressive agents, and immunoglobulin were administered for polymyositis, and another EGFR-TKI, afatinib, was administered for lung adenocarcinoma. Even though the clinical courses of lung cancer and polymyositis were not parallel, both disease entities subsided. Conclusion. Polymyositis during lung adenocarcinoma treatment is rare; therefore, it should be considered as a coexisting entity when such patients exhibit elevated serum CK levels.
key words: Lung adenocarcinoma, Creatine kinase, Polymyositis
Received: February 17, 2021
Accepted: April 2, 2021
JJLC 61 (4): 322-326, 2021
