Multiple ground-glass nodules after lobectomy for multiple primary lung cancer: a case report.

Background: Multiple primary lung cancer (MPLC) is classified into synchronous and metachronous types. It is clinically rare for a single patient to present with both types simultaneously. EGFR tyrosine kinase inhibitors (EGFR-TKIs) are the first-line treatment for EGFR-sensitive mutant lung cancer, but their therapeutic value in unresectable GGN-type MPLC requires further validation. Case presentation: A female with no smoking history or family history of tumors underwent examination in March 2020, which revealed multiple ground-glass nodules (GGNs) in the left upper lobe. After ruling out distant metastasis, she underwent left upper lobectomy. Postoperative pathology confirmed synchronous MPLC (sMPLC), and genetic testing identified an EGFR L858R mutation. No adjuvant therapy was administered, and regular follow-up was maintained. In April 2022, follow-up computed tomography (CT) scans detected new multiple tiny GGNs in the left lower lobe. Subsequent monitoring showed progressive nodule enlargement. In 2024, bronchoscopic biopsy was performed, and pathology confirmed minimally invasive adenocarcinoma (MIA), consistent with metachronous MPLC (mMPLC). Considering the patient's previous EGFR mutation and the unresectable nature of the lesions, EGFR-TKI targeted therapy was initiated. After treatment, the multiple GGNs in the left lower lobe gradually shrank and ultimately disappeared, achieving sustained complete remission (CR). Follow-up to date has shown no recurrence or significant adverse reactions. Conclusion: Patients with multiple GGNs may develop both synchronous and mMPLC. For unresectable GGN-type MPLC with a confirmed history of EGFR-sensitive mutations, EGFR-TKI targeted therapy demonstrates definitive efficacy and can achieve complete remission.