Primary hepatic neuroendocrine tumor

Abstract

Summary: Primary hepatic neuroendocrine tumor (PHNET) is a rare type of neuroendocrine tumor (NET) that is also a primary hepatic tumor. Patients are present with almost no specific clinical symptoms and typically present with negative test results and atypical imaging characteristics; therefore, the differentiation of PHNET from other types of primary hepatic masses can be very difficult. In this article, we describe a case of PHNET that mimicked a liver helminth infection in a 57-year-old man. The diagnosis of PHNET in this patient was challenging, and the final diagnosis was based on imaging, histopathology features, and long-term follow-up.

Learning points: An uncommon type of neuroendocrine tumor (NET) is a primary hepatic neuroendocrine tumor (PHNET). Primary hepatic neuroendocrine tumors are rare NET lesions found in the liver, characterized by non-specific clinical and imaging results, which can be easily confused with other liver lesions, including HCC and parasitic lesions. To have a conclusive diagnosis and classification, a mixture of many medical assessment techniques, such as imaging, gastrointestinal endoscopy, nuclear medicine, anatomy, including histopathology, and immunohistochemistry, is essential.

Figure 1

Upper abdominal MRI revealed lesions in the VII segment (white arrow) and IV segment (white arrowhead) of the liver. (A) Hyperintense lesions on T2-weighted image. (B) Hypointense lesions on T1-weighted image. (C) Lesions were hyperintense on diffusion-weighted image.

Figure 2

The lesions were heterogeneous enhancement (white arrow and black arrowhead).

Figure 3

The second abdominal ultrasound. Well-defined hyperechoic lesion with and hypoechoic border identified the seventh segment of the liver.

Figure 4

(A) First abdominal MRI result: T1-weighted, fat-suppressed image showing a 22 × 28 mm nodule in segment VII of the liver (white arrow) and a small, faint lesion in segment IV (white arrowhead). (B) Second abdominal MRI images: T1-weighted, fat-suppressed imaging revealed that liver lesions increased in size after 4 months, with the segment VII mass measuring at 40 × 31 mm (white arrow) and the lesion in segment IV clearly visible and 15 × 23 mm in size (white arrowhead).

Figure 5

Second abdominal MRI images, two lesions (white arrow and white arrowhead) showed restricted diffusion. (A) Lesions were hyperintense on diffusion-weighted image. (B) Lesions were hypointense on apparent diffusion coefficient (ADC) map.

Figure 6

Second abdominal MRI images. (A) lesions were poorly enhancement on arterial phase. There was no washout sign of lesions on the portal phase (B) or delayed phase images (C).

Figure 7

Histopathology: (A) Hematoxylin-eosin staining ×10 magnification. Tumor tissue, bordered by normal liver tissue. The tumor-aligned cells suggested a glandular structure. (B) Hematoxylin-eosin staining ×100 magnification. The tumor cells are uniform, with large, round, or oval nuclei, fine, granular chromatin, and lying to one side, with no abnormal mitotic activity or necrosis.

Figure 8

Immunohistochemistry (A, ×40) Tumor cells are positive for CD56. (B, ×20) Tumor cells are positive for CK marker. (C, ×40) Tumor cells are positive for marker P53. (D, ×20) synaptophysin-positive cells. (E, ×20) Tumor cells are negative with chromogranin marker. (F, ×40) Ki67 index 20%.

Figure 9

PET-CT with ¹⁸F-FDG. (A) CT and (B) PET-CT scans. Two hypometabolic hepatic lesions were observed, and no hypermetabolic lesions were identified in other organs.

Figure 10

Abdominal and chest CT images obtained 15 months after the last check-up. (A) Axial, non-enhanced CT image showing a hypoattenuating lesion in the fourth segment of the liver (white arrowhead) and most of the right lobe (white arrow), with an unclear boundary. (B) Axial, non-enhanced CT image showing a calcified mass in the liver (arrow). (C) Axial CT image in the arterial phase, showing the heterogeneous enhancement of the lesions (white arrow and white arrowhead). (D) Axial CT image in the venous phase, revealing lesions with signs of washout in the venous phase (white arrow and white arrowhead). (E) Coronal CT images in the venous phase, showing complete thrombosis of the right branch of the portal vein (white arrow). (F) No lesions were observed on thoracic CT.