A case of solitary paraaortic lymph node recurrence of lung squamous cell carcinoma after resection

Solitary abdominal paraaortic lymph node recurrence after radical lung cancer surgery is very rare. Here, we report a case of a solitary abdominal paraaortic lymph node recurrence of lung squamous cell carcinoma (SCC). A 63-year-old man was diagnosed with lung SCC (cT1cN0M0 stage IA3), underwent a video-assisted right lower lobectomy (ND2a-1), and the pathological findings showed SCC (pT1cN0M0 stage IA3). The EGFR mutation and ALK translocation statuses of SCC were negative, and adjuvant therapy was not performed. Follow-up positron emission tomography - computed tomography (PET/CT) showed a solitary fluorodeoxyglucose (FDG) - concentrated region in the swollen paraaortic lymph node. A paraaortic lymph node biopsy was performed by open laparotomy, to determine the precise diagnosis and identify the genetic status. Pathological findings revealed that the paraaortic lymph node contained poorly differentiated SCC, which was thought to metastasize from the lung cancer. The genetic status of the lymph node recurrence revealed a lack of EGFR mutations, ALK translocations, and ROS1 mutations, while the tumor proportion score (TPS) of PD-L1 was 55%, and we therefore administered pembrolizumab, an immune checkpoint inhibitor. Biopsies are very important for achieving precise diagnoses and determining the genetic statuses of tumors, since molecular-targeting drugs and immune checkpoint inhibitors are available.