Hepatocellular Malignant Neoplasm-NOS: A Clinicopathologic Study of 11 Cases from a Single Institution

Abstract

Aims

The primary aim of this study is to characterize hepatocellular malignant neoplasm, NOS (HEMNOS), a new provisional entity describing a subset of paediatric hepatocellular tumours, which have histological features of neither typical hepatoblastoma (HB) nor hepatocellular carcinoma (HCC).

Methods and results

The clinicopathological features of 11 patients with HEMNOS were analyzed retrospectively. The median age and serum alpha-fetoprotein level at diagnosis was 7 years and 182,000 ng/mL respectively. Ten patients presented with PRETEXT stage III/IV multifocal tumours, eight with major vascular involvement, three with lung metastases, and three with extrahepatic extension. The original pathology diagnoses were: HB in seven patients, HCC in two and HEMNOS in two. Our pathology review of pre-chemotherapy specimens showed that six tumours had equivocal/overlapping histological features of HB and HCC, four had predominant HB histology along with focal HCC-like histology, and one had HB histology. Seven of nine post-chemotherapy resection specimens showed predominant HCC-like histology. Beta-catenin, glypican 3 and spalt-like transcription factor 4 immunostaining showed that all the tumours had a mixed HB/HCC immunophenotype. Telomerase reverse-transcriptase immunostaining showed nuclear staining in nine of the eleven tumours. All patients received chemotherapy and achieved gross total primary tumor resection. Nine of the eleven patients were treated with established HB chemotherapy regimens. After a median follow-up of 6.1 years (range, 1.2 to 11.8 years), all patients were in remission.

Conclusions

HEMNOS is a subtype of HB with focal HCC-like histology, a high-risk clinical profile but favorable outcome following chemotherapy and complete tumor resection.

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