Primary hepatic neuroendocrine carcinoma (PHNET) is an exceptionally rare malignancy with limited standardized treatment options. Two patients presented with incidentally detected hepatic masses and nonspecific gastrointestinal symptoms. Case 1 was diagnosed as primary hepatic neuroendocrine carcinoma (NEC, G3), and Case 2 as primary hepatic large-cell neuroendocrine carcinoma (LCNEC, G3), based on histopathology and immunohistochemistry after excluding extrahepatic origins. Case 1 received transarterial chemoembolization (TACE), etoposide-cisplatin chemotherapy, hepatic arterial infusion chemotherapy (HAIC), and octreotide. Case 2 underwent 3 cycles of drug-eluting bead TACE (d-TACE), HAIC, and long-acting octreotide for symptomatic control of diarrhea. Case 1 experienced progressive disease and died of sepsis. Case 2 achieved significant tumor regression, allowing curative resection. No recurrence was observed at one-month follow-up. The combination of d-TACE, HAIC, and octreotide may provide a potential downstaging approach for unresectable PHNET, but evidence remains preliminary and hypothesis-generating.

A 4-year-old female-spayed French bulldog presented with symptoms of anorexia, lethargy and vomiting. Abdominal ultrasonography revealed multiple coalescing hyperechoic nodules in the liver. Single-phase contrast-enhanced computed tomography (CT) scan showed heterogeneous liver lobes with hyperattenuating parenchyma and multiple hypoattenuating lesions in the post-contrast phase. No other primary neoplastic lesions were observed. Laparoscopic liver biopsy, histopathology and immunohistochemistry confirmed primary hepatic neuroendocrine carcinoma (PHNEC). Consequently, in cases where multiple hyperechoic nodules on ultrasound and hypoattenuating nodules on post-contrast CT are observed in the liver, PHNEC should be considered as a differential diagnosis.

BACKGROUND Primary hepatic neuroendocrine neoplasms (PHNENs), including primary hepatic neuroendocrine carcinoma (PHNEC), are extremely rare. PHNENs typically exhibit slow growth, although mixed neuroendocrine-non-neuroendocrine neoplasms have poor prognoses. PHNENs are also challenging to diagnose. CASE REPORT A 73-year-old man underwent plain computed tomography (CT), which incidentally detected a 42-mm solitary hepatic tumor. Serum levels of protein induced by vitamin K absence or antagonist-II (PIVKA-II) were elevated at 138 mAU/mL. Thirteen days later, magnetic resonance imaging (MRI) revealed an enlarged hepatic tumor with tumor thromboses extending into the hepatic and portal veins. No early-phase enhancement was observed. At 18 days, Doppler ultrasound and dynamic CT evaluated the tumor as hypovascular, and a newly swollen solitary lymph node appeared. At 39 days, positron emission tomography (PET)/CT revealed strong uptake in the primary liver tumor and metastatic lymph nodes, with additional distant lymph node metastases emerging. At 49 days, a metastatic cervical lymph node was surgically resected. At 61 days, PHNEC was definitively diagnosed based on histopathological and immunohistochemical assessments. The Ki-67 labeling index was >90%. At 67 days, he was hospitalized to begin chemotherapy, but CT revealed end-stage disease. Palliative treatment was required, and the patient died of cancer 82 days after the initial diagnosis. CONCLUSIONS We have presented a thought-provoking case of PHNEC with rapid oncological progression. To clarify clinical implications (eg, atypical imaging features and diagnostic pitfalls), detailed imaging findings are provided. We anticipate that this case will be informative for clinicians in this field.

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Primary hepatic Neuroendocrine carcinoma (PHNEC) is exceptionally rare, and when it cannot be surgically removed locally, systemic combination therapy is the preferred treatment. However, current treatments have shown limited effectiveness, and more effective approach remains a matter of debate. We present a case involving a female patient diagnosed with non-surgically suitable PHNEC, confirmed through pathology. Following four cycles of standard first-line systemic chemotherapy, this intervention was prompted by imaging indicating suboptimal local lesion control, the patient underwent localized interventional and microwave ablation therapy. Subsequently, an evaluation based on mRECIST criteria revealed complete remission post-procedure. The disease sustained this remission status throughout the 14-month follow-up, with the administration of 14 cycles of immunocheckpoint inhibitor maintenance therapy, showing no signs of local recurrence or distant metastasis and devoid of any associated complications. This case introduces a novel therapeutic avenue for individuals who are ineligible for surgery and have not responded to systemic chemotherapy. The diagnosis and management of PHNEC are deliberated within the framework of this particular case.