Utility of contrast‐enhanced harmonic endoscopic ultrasonography for predicting the prognosis of pancreatic neuroendocrine neoplasms

Background and Aims Pancreatic neuroendocrine neoplasms (PanNENs), including Grade 1 (G1) or G2 tumors, can have a poor prognosis. This study investigated the value of contrast‐enhanced harmonic endoscopic ultrasonography (CH‐EUS) for predicting the prognosis of PanNENs. Methods This single‐center, retrospective study included 47 consecutive patients who underwent CH‐EUS and were diagnosed with PanNEN by surgical resection or EUS‐guided fine needle aspiration between December 2011 and February 2016. Patients were divided into aggressive and non‐aggressive groups according to the degree of clinical malignancy. CH‐EUS was assessed regarding its capacity for diagnosing aggressive PanNEN, the correspondence between contrast patterns and pathological features, and its ability to predict the prognosis of PanNEN. Results There were 19 cases of aggressive PanNEN and 28 cases of non‐aggressive PanNEN. The aggressive group included three G1, four G2, three G3 tumors, three mixed neuroendocrine non‐neuroendocrine neoplasms, and six neuroendocrine carcinomas. CH‐EUS was superior to contrast‐enhanced computed tomography for the diagnosis of aggressive PanNEN ( P < 0.001): hypo‐enhancement on CH‐EUS was an indicator of aggressive PanNEN, with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 94.7%, 100%, 100%, 96.6%, and 97.9%, respectively. Among G1/G2 PanNENs, cases with hypo‐enhancement on CH‐EUS had a poorer prognosis than those with hyper/iso‐enhancement ( P = 0.0009). Assessment of 36 resected specimens showed that hypo‐enhancement on CH‐EUS was associated with smaller and fewer vessels and greater degree of fibrosis. Conclusion Contrast‐enhanced harmonic endoscopic ultrasonography may be useful for predicting the prognosis of PanNENs.