Introduction and importance: Primary hepatic neuroendocrine tumors (PHNETs) are extremely rare, and the clinical symptoms, test results, and imaging characteristics are nonspecific in most patients; thus, it is difficult to differentiate from other liver masses before surgery. Histopathology and immunohistochemistry are the main basis for the diagnosis. PHNETs and colon tumors co-occur in a patient and are non-homologous, as reported in the English-language literature for the first time.
Case presentation: We present a case of a 60-year-old woman with right hepatic lobe mass accidentally discovered on abdominal ultrasonography during a routine examination. Preoperative liver contrast-enhanced computed tomography suggested hepatocellular carcinoma; then, surgery were performed. Pathological results revealed a Grade 2 neuroendocrine tumor of the liver. In search of the primary tumor, upper and lower endoscopy of the GI tract was performed and revealed a mass in the ascending colon. Ascending colon cancer was considered; then, laparoscopic right hemicolectomy was performed. Pathological results suggested tubular villous adenoma of the ascending colon. The final diagnosis was not colon cancer with liver metastases but was PHNETs with colon adenoma.
Clinical discussion: PHNETs are rare cancers that are difficult to diagnose, requiring not only differentiation from other liver masses but also exclusion of metastases from extrahepatic sources. The pathological results play an important in making an accurate diagnosis.
Conclusion: Pathology, postoperative follow-up, and comprehensive imaging examinations are powerful tools in the diagnosis of PHNETs. Currently, surgery is the best treatment to achieve a potential cure and prolong the patient's survival.
Keywords: Case report; Colon adenoma; Diagnosis; NETs; PHNETs; Pathology.
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