[A Case of Drug-Induced Pneumomediastinum Preceding Interstitial Pneumonitis Onset during Treatment with a First-Line Regimen of GnP in a Patient with Unresectable Pancreatic Cancer].

Background: The highest prevalence of drug-induced interstitial pneumonitis(IP)occurs in patients receiving antineoplastic agents, such as cytotoxic chemotherapeutic drugs, molecular targeted drugs, and immune checkpoint inhibitors. A certain period of the treatment for IP requires discontinuation of the anticancer therapy, resulting in progression of the malignant status.

Case: A 70-year-old man was incidentally diagnosed with locally advanced unresectable pancreatic cancer in the course of his treatment for ventricular dysrhythmia. After the insertion of a pacing instrument, he was ensured to be eligible to receive combination chemotherapy with gemcitabine and nab-paclitaxel(GnP)as the primary regimen. Shortly after the second course of GnP, the patient had high fever and developed pneumomediastinum 3 days prior to the onset of IP. The GnP treatment was suspended, and the IP was treated with pulse steroid therapy. The respiratory disorder took approximately 3 months to resolve; however, this concomitantly led to aggravation of the malignancy, which developed multiple metastases to the liver. The patient was no longer allowed to receive antineoplastic treatment.

Conclusion: Although GnP may be a key regimen for the treatment of unresectable pancreatic cancer, patients should be closely monitored to ensure early detection of adverse events, such as interstitial pneumonia. Furthermore, drug-induced pneumomediastinum may be a precursor to the onset of interstitial pneumonia.