Radiation myositis and myonecrosis of the chest wall after stereotactic body radiation therapy for non-small cell lung cancer: A case report

Abstract

Rationale: Stereotactic body radiation therapy (SBRT) for early-stage lung cancer, especially non-small cell lung cancer (NSCLC), is characterized by a high local control rate and low rate of severe toxicity. The adverse events of SBRT for NSCLC can involve the lung parenchyma, bronchi, central airway, esophagus, large vessels, and chest wall. Studies on muscle inflammation or necrosis caused by SBRT are relatively sparse compared to other tissues because muscles are in general resistant to radiation. Here we present a case of inflammation and necrosis of the pectoral muscle as an adverse event of SBRT. Patient concerns: A 90-year-old male patient with NSCLC of the left upper lung underwent an SBRT as a definitive therapy. His left anterior thorax swelled up and became hot and painful without obvious cutaneous injury 6 months after the radiation therapy. Diagnosis: Computed tomography and contrast-enhanced magnetic resonance imaging suggested inflammation and necrosis centered at the pectoral muscles. Intervention: none. Outcome: The pain and heat sensation spontaneously remitted within 6 weeks. However, the affected area became stiff, and the swelling partly remained for 18 months after radiation. Lessons: Radiation myositis and/or necrosis are rare adverse events of SBRT. Radiation myositis and necrosis that occurred in our patient was somewhat difficult to diagnose because he did not receive any chemotherapy. We should be aware of the fact that these adverse events could occur in patients without such specific backgrounds.