Case Report: Alternative biopsy targets plus CEUS-guided omental puncture: enabling CLDN18.2 detection and precision therapy enrollment in pancreatic cancer.

Introduction: Some primary pancreatic cancer lesions are located deep in the abdomen and adjacent to major blood vessels, which leads to procedural risk and low success rates of percutaneous biopsy. This situation creates substantial obstacles for pathological diagnosis and biomarker detection. Methods: We present a 54-year-old female patient diagnosed with malignant pancreatic body carcinoma. The primary tumor was in close proximity to the splenic artery and accompanied by omental metastatic nodules. After multidisciplinary team discussion, we selected the safely accessible omental metastatic lesions as alternative biopsy targets and performed core needle biopsy under contrast-enhanced ultrasound (CEUS) guidance for tissue sampling. Results: Pathological examination confirmed adenocarcinoma, and the immunophenotype was consistent with a pancreatobiliary origin. Immunohistochemical staining revealed high CLDN18.2 expression. The patient was subsequently enrolled in a clinical trial for CLDN18.2-directed combination therapy. Serial imaging follow-up demonstrated measurable shrinkage of both the primary tumor and metastatic lesions. Discussion: When imaging and clinical evaluations strongly indicate a solitary pancreatic malignancy and safely accessible metastatic lesions are present, the strategy of CEUS-guided alternative target biopsy serves as a viable approach to acquire tissue specimens and conduct biomarker testing. Nonetheless, its diagnostic concordance and clinical generalizability remain to be validated in large-sample studies.