Diagnostic utility of EUS-FNA in distinguishing hepatocellular carcinoma from gastric submucosal tumor: A case report.

INTRODUCTION AND IMPORTANCE: Extrahepatically growing hepatocellular carcinoma (HCC) account for only 0.3 %-2.4 % of all hepatocellular carcinoma cases. We present the rare case of a patient in whom endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) was used to distinguish an extrahepatically growing HCC from a gastric submucosal tumor. CASE PRESENTATION: The patient was a 44-year-old man who underwent an esophagogastroduodenoscopy (EGD) and was found to have a submucosal tumor (SMT). A gastrointestinal stromal tumor was suspected. Computed tomography (CT) showed an unclear connecting between the tumor and the liver. On immunohistochemical analysis, the tumor cells were positive for CK7, PIVKA-II, and glypican-3, and negative for C-kit. Based on these findings, HCC was suspected, and ethoxybenzyl diethylenetriamine-enhanced magnetic resonance imaging (EOB-MRI) was performed. EOB-MRI revealed the connecting of the tumor and the liver. Thus, the patient was diagnosed as having an extrahepatically protruding HCC, and laparoscopic S2 partial hepatectomy was performed. Pathologically, the tumor was identified as a moderately differentiated HCC. According to the 8th edition of the UICC TNM Classification, the tumor was classified as T1bN0M0 and stage IB. CLINICAL DISCUSSION: Owing to its rarity, the diagnosis of an extrahepatically protruding HCC is often difficult when the differentiation of a gastric SMT and HCC is unclear on CT. As in this case, if an HCC is also differentiated on hematoxylin and eosin staining after EUS-FNA, immunohistochemistry findings can help in the diagnosis. CONCLUSION: The findings show that EUS-FNA could be helpful for diagnosis when an HCC needs to be differentiated from a gastric SMT.