RESUMO
OBJECTIVES: Sonic hedgehog hepatocellular adenoma (shHCA) is a new hepatocellular adenoma (HCA) subgroup characterized by high risk of hemorrhage. ShHCA account for below 10% of all HCA cases and are often associated with female gender, obesity, and non-alcoholic steatohepatitis. No specific MRI characteristics have been described to date. The objective of this study was to assess the value of using MRI to identify shHCA, and correlate MRI findings with histology. METHODS: We retrospectively collected MRI scans of 29 patients with shHCA from our center and from different liver referral centers to include 35 lesions. Diagnosis of shHCA was assessed by immunohistochemical overexpression of argininosuccinate synthase 1 or prostaglandin D2 synthase, then confirmed by molecular analysis of sonic hedgehog pathway activation and/or by proteomic analysis. RESULTS: In 46% (n = 16/35) of shHCA cases, we detected intralesional fluid-filled cavities defined on MR images as fluid-like foci markedly hyperintense on T2-weighted sequences, and hypointense on T1-weighted sequences, with or without delayed enhancement. Pathologically, these cavities were observed in 54% of cases as vacuoles filled with blood at different stages of degradation. Hemorrhage and/or necrosis were detected among 71% of cases by MRI analysis (n = 25/35) versus 82% pathologically. Seventeen percent of shHCA cases (n = 6/35) were completely homogeneous via MRI and pathological analysis. No MRI criteria was found in favor of focal nodular hyperplasia, HNF1A-mutated HCA, or typical inflammatory HCA. CONCLUSION: We reveal the presence of intralesional fluid-filled cavities among 46% of our shHCA cases that represent a new MRI finding possibly helpful for shHCA diagnosis. CLINICAL RELEVANCE STATEMENT: This multicenter study is the first clinical study about the radiological aspect of this new hepatocellular adenoma subgroup. This highlights a strong correlation between MRI and histological analysis, with a specific pattern emerging for diagnosis. KEY POINTS: ⢠Sonic hedgehog hepatocellular adenoma is a new hepatocellular adenoma subgroup associated with high risk of hemorrhage, but imaging features of this subgroup remain unknown. ⢠Analysis of MR images and correlation with pathology revealed intralesional fluid-filled cavities and necrotic-hemorrhagic changes. ⢠Intralesional fluid-filled cavities have not yet been described in other adenoma subtypes and represent a new MRI finding for sonic hedgehog hepatocellular adenoma.
RESUMO
Hepatocellular adenomas (HA) are rare benign liver tumors known to affect mainly women of reproductive age taking oral contraception. They can be complicated by hemorrhage or malignant transformation to hepatocellular carcinoma, especially when the size of the lesion exceeds 5 cm. Magnetic resonance imaging is the most specific tool for the non-invasive characterization of HA. The discovery of mutations underlying different specific HA phenotypes has allowed the establishment of a molecular classification that modified the management of this pathology.
Les adénomes hépatocellulaires (AH) sont des tumeurs bénignes du foie rares et connues pour affecter principalement les femmes en âge de procréer prenant une contraception orale. Ils peuvent se compliquer d'hémorragie ou de transformation en carcinome hépatocellulaire, en particulier lorsque la taille de la lésion dépasse 5 cm. L'imagerie par résonance magnétique est la technique la plus spécifique pour caractériser les AH de manière non invasive. La découverte de mutations spécifiques témoignant de l'existence de différents phénotypes d'AH a permis l'établissement d'une classification moléculaire qui a modifié la prise en charge de cette pathologie.
