Primary hepatic neuroendocrine neoplasms: imaging characteristics and misdiagnosis analysis

Abstract

Objective: To analyze the CT and MR features of Primary hepatic neuroendocrine neoplasms (PHNENs) in order to enhance the diagnostic accuracy of this disease.

Methods: A retrospective analysis was conducted on patients diagnosed with hepatic neuroendocrine neoplasms, excluding other sites of origin through general examination and postoperative follow-up. The CT and MR signs were analyzed according to the 2018 version of Liver Imaging Reporting and Data System (LI-RADS), along with causes of misdiagnosis.

Results: Twelve patients, including 6 males and 6 females, were enrolled in this study. There was no significant increase in liver tumor markers among all cases. Most masses were multiple (9/12), exhibiting low attenuation on pre-contrast CT scans, T1-hypointense signal, T2-hyperintense signal, and restricted diffusion. The majority of these masses (7/10) demonstrated similar rim arterial phase hyper-enhancement as well as peripheral "washout" during venous portal phase and delayed phase imaging. Three cases had incomplete capsules while one case had a complete capsule. Cyst/necrosis was observed in 7 out of all cases following administration of contrast agent, with 5 mainly distributed in the periphery. All masses lacked fat, calcification, vascular or bile duct tumor thrombus formation.

Conclusion: The imaging findings associated with PHNENs possess certain specificity, often presenting as multiple masses within the liver accompanied by peripheral cyst/necrosis, similar rim arterial phase hyper-enhancement during venous portal phase and delayed phase imaging.

Keywords: diagnosis; liver; magnetic resonance imaging; neuroendocrine neoplasms; tomography; x-ray computed.

Figure 1

Flowchart depicting the process of case enrollment.

Figure 2

Female, aged 53 years, with an incidental liver mass and normal liver-related tumor markers; NSE was not tested. In November 2019, contrast-enhanced MR Imaging led to the preliminary diagnosis of hepatic adenoma. The liver exhibited three masses in S2, 3, and 8, characterized by low signal intensity on T1WI (A) and high signal intensity on T2WI (D). These masses showed limited diffusion (C) without any apparent fat component (A, B), and heterogeneous hyper-enhancement throughout the tumor on arterial phase with “wash-out” on venous portal and delayed phases, with localized inversion enhancement (E, F), white arrow) and capsule (F), white triangle) in the delayed phase. Subsequently, in December 2019, laparoscopic left hemihepatectomy and microwave ablation were performed for the treatment of the liver tumor. Postoperative pathology confirmed the presence of hepatic neuroendocrine tumor (G2). The patient remains alive with no evidence of extrahepatic NENs.

Figure 3

Female, aged 50 years, presented with right upper quadrant abdominal tightness and pain persisting for five days along with abdominal distention, occasional dizziness, and fatigue. Liver-related tumor markers as well as NSE levels were within normal range. A preliminary diagnosis of hepatocellular carcinoma with multiple metastases was made based on contrast-enhanced CT findings in May 2018. The masses located at hepatic S4 and 8 displayed a round mildly lobulated mass measuring up to a maximum cross-section size of approximately 90.4mm x80.5mm; it had well-defined boundaries and appeared slightly heterogeneous hypodense on pre-contrast CT images. Irregular circumferential hyperenhancement was observed on arterial phase imaging along with thickened and thickened tumor blood vessels (B), black arrow head), while peripheral “washout” on venous portal phase and delayed phase accompanied by incomplete capsule (C, D), black arrow). A radially low attenuation area with no apparent enhancement is seen in the center of the mass (A-D), black asterisk). CT value of the most obvious enhanced area/normal hepatic parenchyma: pre-contrast 46.3/52.1; arterial phase 95.0/62.2; venous portal phase 92.9/101.8; delay phase 78.4/87.6. Enlarged right half liver resection was performed in May 2018. Postoperative pathology: neuroendocrine carcinoma (G3). EP chemotherapy regimen was performed after surgery, and the patient remains alive with no evidence of extrahepatic NENs.

Figure 4

Female, aged 49 years, incidentally discovered multiple liver masses. The levels of CEA were measured at 10.53ng/ml, PIVKA at 56mAU/ml, CA199 at 237.15U/ml, and NSE levels were within the normal range. Based on contrast-enhanced CT in July 2022, the preliminary diagnosis included: (1) gastric malignant stromal tumor with multiple hepatic metastases; (2) possibility of primary liver tumors not excluded due to the presence of a large mass in the right lobe. Multiple round-like masses were observed throughout the liver, with the largest lobulated mass measuring approximately 102.7mm x 71.9mm in cross-section located in S7 and S8 segments. The contrast-enhanced scan revealed irregular annular arterial phase hyper-enhancement and peripheral “washout” in venous portal phase and delayed phase. Some smaller lesions exhibited whole-tumor enhancement (A-D), black triangle). Additionally, multiple cystic foci were identified mainly in the periphery of the lesion as well as smaller lesion (D), black arrow). Biopsy results confirmed a neuroendocrine tumor (G2) for this liver mass, and the patient remains alive with no evidence of extrahepatic NENs. The pathology report for another operation involving caudal pancreatic space occupying lesion showed solid pseudopapillary tumor of the pancreas.

Figure 5

Histogram of CT values of lesions and normal hepatic parenchyma on each phase. 1、NCTVs, CT values of normal hepatic parenchyma; 2、LCTVs, CT values of lesions; 3、PC, pre-contrast; AP, arterial phase; PP, venous portal phase; DP, delayed phase.

Figure 6

Curve of Z-score CT values of lesions and normal hepatic parenchyma on each phase. 1、Zscore(NCTVs), Z-score of CT values of normal hepatic parenchyma; 2、Zscore(LCTVs), Z-score of CT values of lesions; 3、PC, pre-contrast;AP, arterial phase; PP, venous portal phase; DP, delayed phase; 4、·*indicates that the difference was statistically significant.