Peliosis hepatis (PH) is a rare benign condition, characterized by hepatic sinusoidal dilatation and blood-filled cystic cavities, often found incidentally, with still challenging diagnosis by imaging due to polymorphic appearance.
Based on a retrospective analysis of our series (12 patients) and systematic literature review (1990-2022), to organize data about PH and identify features to improve characterization.
Retrospective case series and systematic review.
Twelve patients (mean age 48 years, 55% female) with pathology-proven PH and 49 patients (mean age 52 years, 67% female) identified in 33 studies from the literature (1990-2022).
1,5-T; T1-weighted (T1W), T2-weighted (T2W), diffusion-weighted (DW), contrast-enhanced (CE) T1W imaging.
We compared our series and literature data in terms of demographic (gender/age/ethnicity), clinical characteristics (symptoms/physical examination/liver test), associated conditions (malignancies/infectious/hematologic/genetic or chronic disorders/drugs or toxic exposure) percentage. On magnetic resonance imaging lesion numbers/shape/mean maximum diameter/location/mass effect/signal intensity were compared. PH pathological type/proposed imaging diagnosis/patient follow-up were also considered.
Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Case Reports/Series quality assessment. Intraclass correlation and Cohen\'s kappa coefficients for levels of inter/intrareader agreement in our experience.
Patients were mainly asymptomatic (92% vs. 70% in our study and literature) with associated conditions (83% vs. 80%). Lesions showed homogeneous T1W-hypointensity (58% vs. 65%) and T2W-hyperintensity (58% vs. 66%). Heterogeneous nonspecific (25% vs. 51%), centrifugal (34% vs. 8%), or rim-like centripetal (25% vs. 23%) patterns of enhancement were most frequent, with hypointensity on the hepatobiliary phase (HBP), without restricted diffusivity. Good inter- and intrareader agreement was observed in our experience. Concerning JBI Checklist, 19 out of 31 case reports met at least 7 out of 8 criteria, whereas 2 case series fulfilled 5 and 6 out of 10 items respectively.
A homogeneous, not well-demarcated T1W-hypointense and T2W-hyperintense mass, with heterogeneous nonspecific or rim-like centripetal or centrifugal pattern of enhancement, and hypointensity on HBP, may be helpful for PH diagnosis. Among associated conditions, malignancies and drug exposures were the most frequent.
4 TECHNICAL EFFICACY: Stage 2.

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related deaths in the world, with hepatitis B and C as its main causes. HCC can have fat metamorphosis which leads to a better prognosis, though this is more commonly found in lesions smaller than 3 cm in diameter, and usually contains intravoxel fat. In this case series, we present three cases of HCC with macroscopic fat metamorphosis as examined using CT scan and MRI. Macroscopic fat is seen using CT as a hypodense mass with attenuation of -10 to -100 HU, or MRI using fat-saturation technique. Intravoxel fat can be seen on MRI using fat saturation chemical shift technique, appearing as signal loss during opposed phase and increased signal during in-phase. The differential diagnoses of HCC with fat metamorphosis are angiomyolipoma, hepatic adenoma, nodular steatosis, focal nodular hyperplasia, dysplastic nodule, liposarcoma, and hepatic metastasis. Enhancement patterns of the fat and non-fat component; intra-tumoral fat distribution; the presence of cirrhosis; the presence of atoll sign; and history of viral hepatitis are useful clues for differentiation of HCC with other differential diagnoses.

BACKGROUND: Hepatocellular adenoma (HCA) is a rare benign liver tumor usually affecting young women with a history of prolonged use of hormonal contraception. Although the majority is asymptomatic, a low proportion may have significant complications such as bleeding or malignancy. Despite responding to the hormonal stimulus, the desire for pregnancy in patients with small HCA is not contraindicated. However, through this work we demonstrate that intensive hormonal therapies such as those used in the treatment of infertility can trigger serious complications.
METHODS: A 33-year-old female with a 10-year history of oral contraceptive use was diagnosed with a hepatic tumor as an incidental finding in an abdominal ultrasound. The patient showed no symptoms and physical examination was unremarkable. Laboratory functional tests were within normal limits and tests for serum tumor markers were negative. An abdominal magnetic resonance imaging (MRI) was performed, showing a 30 mm × 29 mm focal lesion in segment VI of the liver compatible with HCA or Focal Nodular Hyperplasia with atypical behavior. After a total of six years of follow-up, the patient underwent ovulation induction treatment for infertility. On a following MRI, a suspected malignancy was warned and hence, surgery was decided. The surgical specimen revealed malignant transformation of HCA towards trabecular hepatocarcinoma with dedifferentiated areas. There was non-evidence of tumor recurrence after three years of clinical and imaging follow-up.
CONCLUSIONS: HCAs can be malignant regardless its size and low-risk appearance on MRI when an ovultation induction therapy is indicated.

Perivascular epithelioid cell tumor (PEComa) of liver is extremely rare hepatic neoplasm with only 30 cases reported in the literature. These lesions are found mainly in young females and may present a potential pitfall in the characterisation of focal liver lesions. The biological behavior of PEComa varies from generally benign to rarely malignant and metastatic disease. We report a case of a patient with hepatic PEComa with the corresponding imaging findings on the ultrasound, contrast-enhanced ultrasound (CEUS) and hepatospecific MRI. After failed attempt to characterize the lesion by percutaneous biopsy, surgical resection was conducted and the final diagnosis was achieved.