Comparison of MRI Features of Epithelioid Hepatic Angiomyolipoma and Hepatocellular Carcinoma: Imaging Data From Two Centers

Abstract

Introduction: Epithelioid hepatic angiomyolipoma (Epi-HAML) can easily be misdiagnosed as a malignant tumor such as hepatocellular carcinoma (HCC) because of the low-fat content on imaging. We analyzed and compared the magnetic resonance imaging (MRI) features of Epi-HAML and HCC, which would aid in disease diagnosis.Methods: We included 30 pathologically confirmed patients with Epi-HAML and 80 with HCC, who underwent both MRI unenhanced scan and three-phase contrast-enhanced MRI scan. The clinical and MRI features of the two groups were summarized and analyzed.Results: Epi-HAML showed significant differences compared to HCC group in terms of clinical features such as sex preference, age, concomitant diseases (hepatitis B and cirrhosis), and elevated plasma alpha-fetoprotein (AFP) (P < 0.001). In addition, there were statistically significant differences between both tumor types with regard to conventional MRI findings such as a solitary tumor (100 vs. 83.8%, P = 0.018), well-defined (93.3 vs. 71.3%, P = 0.027), mild hyperintensity (40.0 vs. 3.7%, P < 0.001) on DWI with high b-value, fat within the tumor (43.3 vs. 8.8%, P < 0.001), and rare necrosis (3.3 vs. 26.3%, P = 0.016). Besides, Epi-HAML displayed significant differences compared to HCC in terms of contrast-enhanced MRI characteristics such as draining hepatic vein (30.0 vs. 3.8%, P < 0.001), portal vein tumor thrombus (0 vs. 13.8%, P = 0.033), hypointensity at delayed phase (70.0 vs. 95%, P = 0.001), intra-tumor vessel at delayed phase (36.7 vs. 10.0%, P = 0.003), pseudocapsule (20.0 vs. 78.8%, P < 0.001), and prolonged enhancement (56.7 vs. 1.2%, P < 0.001).Conclusion: Epi-HAML frequently occurs in middle-aged women and usually lacks characteristic clinical symptoms. Typically, Epi-HAML presents as an isolated and well-defined tumor with rich vasculature. Specific MRI features such as intra-tumor fat, intra-tumor vessel, draining hepatic vein, prolonged enhancement, and lack of capsule may contribute to a more confident diagnosis of Epi-HAML.

Differentiating Hepatic Epithelioid Angiomyolipoma From Hepatocellular Carcinoma and Focal Nodular Hyperplasia via Radiomics Models

“…Previous imaging studies have observed that HEAML has specific radiological characteristics that may help with diagnostic evaluation on computed tomography (CT) and magnetic resonance imaging (MRI) ( 4 – 12 ). Definite existence of a small amount of fat in hepatic mass is greatly valuable in radiological diagnosis of HEAML, for which MRI scan is recommended ( 8 , 10 ). Also, HEAML as a blood-rich tumor would be included in the differential diagnosis when draining vein of the hepatic mass was observed in the arterial phase ( 6 , 8 ).…”

“…Definite existence of a small amount of fat in hepatic mass is greatly valuable in radiological diagnosis of HEAML, for which MRI scan is recommended ( 8 , 10 ). Also, HEAML as a blood-rich tumor would be included in the differential diagnosis when draining vein of the hepatic mass was observed in the arterial phase ( 6 , 8 ). In contrast to the wash-in and wash-out pattern of HCC, HEAML may have persistently high enhancement of the intertumoral focal area on contrast-enhanced CT or MRI ( 4 – 12 ).…”

Hepatic Angiomyolipoma

“…The AT was the time the first microbubble reached the lesion; ascending slope, Ascending function for wash‐in; TTP, time needed to reach PI; PI, maximum intensity of the TIC during bolus transit; FT, time when the intensity dropped to half the PI; and MTT, time needed to reach the FT from the AT. The following MRI findings (including T1W and T2W sequences, a DWI sequence with b of 1000 s/mm 2 , and enhanced imaging) were analyzed: early draining vein and tumor vessels, intratumor fat, absence of pseudocapsules and signal intensity on a DWI sequence with a high b value, and hypointensity in the delayed phase …”

“…The following MRI findings (including T1W and T2W sequences, a DWI sequence with b of 1000 s/mm 2 , and enhanced imaging) were analyzed: early draining vein and tumor vessels, intratumor fat, absence of pseudocapsules and signal intensity on a DWI sequence with a high b value, and hypointensity in the delayed phase. 17,18 Pathologic Diagnosis of AML The final pathologic diagnosis of AML and HCC in surgical specimens was made by an experienced pathologist with 30 years of pathology experience, who was unaware of clinical information and imaging findings, including CEUS and MRI. Tumor tissue sections embedded in paraffin were stained with hematoxylineosin for the histopathologic examination.…”

Clinical characteristics and outcomes of patients with hepatic angiomyolipoma: A literature review

“…Hepatic localization of AML, described for the first time in 1976[ 2 ], is rare, since only around 600 cases were reported after an exhaustive search of the literature up to the year 2017[ 3 ]. Hepatic AML (HAML) poses a veritable diagnostic challenge in radiological terms, especially when fat content is low, because this type of tumor may appear as a hypervascular tumor associated with a washout phase that mimics other, more common hypervascular hepatic tumors, such as hepatocellular carcinoma[ 4 - 7 ]. The natural course of HAML is mostly benign, although several cases have been reported to exhibit aggressive behavior with metastasis or recurrence after surgery[ 8 - 24 ], or spontaneous rupture[ 8 , 25 - 33 ].…”