Abstract: Objective To analyze the clinical manifestations, severity grading, management, and prognosis of interstitial pneumonitis that occurred during the treatment of gastric stromal tumors with imatinib mesylate tablets so as to provide guidance for clinicians. Methods The clinical data of a patient who developed interstitial pneumonitis during the treatment of her gastric stromal tumor with oral imatinib mesylate was analyzed. Additionally, the related literature was reviewed and summarized. Results The patient developed cough and sputum while she was treated with imatinib mesylate. After correlation analysis and multidisciplinary consultation, the patient was diagnosed with imatinib-induced interstitial pneumonia. Imatinib mesylate was discontinued, and glucocorticoid therapy was initiated. The patient’s clinical symptoms and imaging findings gradually improved. Literature review showed that imatinib mesylate could cause interstitial pneumonia, with such common clinical symptoms as dyspnea, cough, sputum production and shortness of breath. Chest CT often showed ground-glass opacities and reticular fibers. The clinical severity of the condition could be classified into four grades, and immediate treatment led to a good prognosis. Conclusion Clinicians should be alert to the risk of adverse drug reactions and conduct a safety assessment before using imatinib mesylate. In case of respiratory symptoms during treatment, a range of examinations is recommended. If imatinib-induced interstitial pneumonitis is considered likely, the multidisciplinary team should carry out an all-round assessment and adopt the right treatment regimen according to the severity grade to improve the patient’s prognosis.

Key words: Imatinib Mesylate, Gastric Stromal Tumor, Drug-Related Lung Injury, Interstitial Pneumonia, Adverse Drug Reaction