Navigating Diagnostic Challenges: Primary Pulmonary Choriocarcinoma Depicted by Fluorodeoxyglucose (FDG)-Positron Emission Tomography-Computed Tomography (PET/CT).

This report explores a noteworthy case diagnosed with primary pulmonary choriocarcinoma (PPC), a rare and often fatal non-seminomatous germ cell tumor. Initially misdiagnosed as lung adenocarcinoma, this case underscores the diagnostic complexities associated with PPC. A 44-year-old woman initially misdiagnosed with non-small lung cancer underwent unsuccessful chemoradiation. Emergency presentation with gastrointestinal bleeding revealed intestinal intussusception and severe anemia, rendering her ineligible for surgery. A thorough assessment, including fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), uncovered an aggressive neoplastic pattern. A subsequent biopsy confirmed PPC. Ten cycles of chemotherapy (cisplatin and etoposide on day 1, followed by etoposide, methotrexate, and dactinomycin on day 8) were offered. A complete metastatic response and a marked primary tumor reduction were evident at the end of therapy by PET/CT. Our findings underscore the importance of whole-body FDG PET/CT in comprehensively evaluating disease extent, displaying aggressive and atypical patterns, and offering guidance in complicated cases under multidisciplinary settings.