A rare case of docetaxel-induced myositis in a patient with a lung adenocarcinoma.

Docetaxel is a cytotoxic taxane frequently used to treat patients with various cancers, including non-small cell lung cancer (NSCLC). Docetaxel is known to cause acute myalgias, arthralgias, and neuropathy, but there have been few published case reports of myositis. Here, we describe a rare case of docetaxel-induced myositis diagnosed based on laboratory data, thigh magnetic resonance imaging (MRI), and electromyography (EEG). A 66-year-old male was admitted for thigh pain and fatigue that onset 1 week prior. He had been diagnosed with stage IVA (cT4N0M1a) NSCLC 3 years ago and had been started on docetaxel (60 mg/m2 intravenously every 3 weeks; fourth-line chemotherapy) 1 month earlier. After the second cycle, he developed both thigh pain and fatigue. On admission, his creatinine phosphokinase (CPK) level was elevated, thigh MRI revealed diffuse muscle edema, and EEG showed myogenic changes. We found no plausible cause for myositis except docetaxel. He was diagnosed with myositis and treated with oral prednisolone. His symptoms were relieved and the CPK level declined. Although rare, this case indicates that clinicians should consider the possibility of myositis as a complication in patients on docetaxel.