Hepatocellular carcinoma arising from ectopic liver tissue: a systematic review of the literature.

Ectopic liver tissue (ELT) is a rare congenital anomaly characterized by hepatic parenchyma located outside the native liver. In this systematic review, 55 cases of hepatocellular carcinoma (HCC) arising from ELT were identified through a literature search performed in PubMed, MEDLINE, Scopus, and Web of Science, in accordance with PRISMA 2020 guidelines and registered in PROSPERO (CRD420251084866). The median age was 61 years (IQR: 52-68), and 65.5% were male. Hepatitis B and C were present in 26.5% cases. The most common tumor locations were the subphrenic ( n  = 11), peritoneal ( n  = 7), retroperitoneal ( n  = 6), and pancreatic ( n  = 6) regions. Solitary tumors were reported in 78.2% of cases, with a median tumor size of 71 mm (IQR: 36.5-100). AFP was elevated in 74.4% of patients, and AFP-L3 (100%) and PIVKA-II (72.7%) were elevated in most tested cases. Immunohistochemistry frequently showed positivity for HepPar-1 (88.6%), glypican-3 (81.3%), and arginase-1 (87.5%). Surgical resection was the primary treatment modality, and in addition, transarterial chemoembolization, tyrosine kinase inhibitors, and immune checkpoint inhibitors have been used as therapeutic options. The median follow-up was 17 months (IQR: 12-36), during which 85.4% of patients were alive. Distant metastasis occurred in 18.6% of cases, and local recurrence in 6.7%. In conclusion, ectopic HCC is a rare tumor entity with variable clinical presentations. Despite limited classical risk factors, surgical resection remains associated with a favorable prognosis. Histopathological confirmation is essential for diagnosis, and multimodal treatment strategies should be considered for advanced disease.