Hepatic hemangioendothelioma: CT, MR, and FDG-PET-CT in 67 patients—a bi-institutional comprehensive cancer center review
Dhakshinamoorthy Ganeshan, Perry J. Pickhardt, Ajaykumar C. Morani, Sanaz Javadi, Meghan G. Lubner, Mohab M. Elmohr, Cihan Duran & Khaled M. Elsayes
European Radiology – January 2020 doi.org/10.1007/s00330-019-06637-3
Hepatic epithelioid haemangioendothelioma (HEH) is a rare malignant mesenchymal tumour of the liver. Its aetiology is unclear, however a number of risk factors have been implicated including liver trauma, hepatitis, asbestos and vinyl chloride exposure, OCP use and alcohol. It usually arises in the 3rd to 4th decade of life, with a reported female predilection. Diagnosis of these tumours is challenging in view of the non-specific nature of their presentation and the absence of significant serological abnormalities. They are in fact often misdiagnosed. Prior to this study, there were only a few small case series describing the cross-sectional imaging features of HEH.
One of the described imaging features of HEH is the target appearance, which reflects the histology of the lesion composed of a central core of dense fibrosis surrounded by a concentric layer of proliferating tumour cells, which is in turn often enclosed by a peripheral avascular rim. On T2 weighted MRI, HEH demonstrates a central area of high-signal intensity surrounded by a layer of low signal intensity and a mildly hyperintense outer layer. A similar target appearance is seen on DWI. On hepatobiliary-phase imaging, a central core is non-enhancing and surrounded by a layer of relatively higher signal intensity due to entrapment of contrast within fibrous stroma with a peripheral hypointense halo corresponding to the presence of tumour cells. The lollipop sign has also been described, and refers to the appearance of hepatic and portal veins tapering towards and terminating at or just within the edge of these lesions. Capsular retraction is another associated feature of HEH.
The aim of this study was to evaluate a larger cohort of patients in order to create a more validated description of the potentially specific imaging features for this tumour.
A retrospective review was carried out from records of patients with pathologically proven HHE in two major cancer institutions in the United States from 2008 to 2016. A cohort of 67 patients with a mean age of 47 years and F:M ratio of 2:1 was studied. Contrast enhanced CT examinations were available in 67 cases. Dynamic contrast-enhanced MRI was available in 30 patients, of whom hepatobiliary contrast was used in 8 patients. Diffusion-weighted MRI was available in 18 cases and FDG PET-CT in 13 patients. Imaging was retrospectively reviewed by 3 abdominal radiologists. Note was made of the number, size and location off tumours and the presence of previously reported imaging features described above.
Multifocal HHE was seen in 88% of patients and 96% demonstrated a peripheral subcapsular location. Capsular retraction was noted in 81%. These findings were similar to other studies. Tumour coalescence was seen in 61% of cases, a higher incidence when compared to other studies, possibly due to the fact that there was a higher incidence of multifocal tumours in this cohort. Peripheral ring arterial phase enhancement was present in 33% of CT cases and the targetoid appearance on portovenous phase imaging was seen in 69% of patients. MRI demonstrated heterogenous high T2 signal intensity in 97% of the cases, with the target sign being present in 67% - a higher incidence than in another study; however the latter considered only 10 patients. Diffusion restriction was seen in 61% of the patients who had DWI included which tallies with other studies. Of the 7 patients who had hepatobiliary phase MR imaging performed, the targetoid appearance was seen in 57% of cases. The lollipop sign was demonstrated in 30% of patients (other studies reported this finding in 4 - 54% of cases) and increased FDG uptake in 62% (reported as 67% in a smaller cohort study).
The authors highlight a number of limitations of this study, including this being a retrospective review associated with selection bias, as well as variation in imaging protocols used during the years of the study.
Whilst the above mentioned imaging features are not pathognomonic for HEH, as metastases and cholangiocarcinoma may also demonstrate similar findings, this study serves to validate how the described imaging features should raise the possibility of HEH, aiding in more accurate radiological diagnosis.
REFERENCES:
- Kehagias DT, Moulopoulos LA, Antoniou A, Psychogios V, Vourtsi A, Vlahos LJ. Hepatic epithelioid hemangioendothelioma: MR imaging findings. Hepatogastroenterology 2000; 47:1711 –1713
- Lyburn ID, Torreggiani WC, Harris AC, et al. Hepatic epithelioid hemangioendothelioma: sonography, CT and MR imaging appearances. Am J Roentgenol 2003;180:1359–1364.
- Bartolozzi C, Cioni D, Donati F, et al. Focal liver lesions: MR imaging pathologic correlation. Eur Radiol 2001;11:1374–1388.
Dr. Stephanie Vella is a second-year radiology resident at Mater Dei Hospital, Malta. She completed her undergraduate medical degree at the University of Malta in 2015 and joined the Medical Imaging Department in 2018 where she is undertaking training in diagnostic and interventional radiology.
Comments may be sent to svel0053@gmail.com