The literature on liver cysts is highly conflicting, mostly owing to definitional variations. Two hundred and fifty-eight ≥1 cm cysts evaluated pathologically using updated criteria were classifiable as: I. Ductal plate malformation related (63%); that is, cystic bile duct hamartoma or not otherwise specified-type benign biliary cyst (35 with polycystic liver disease). These were female predominant (F/M=2.4), large (10 cm), often multifocal with degenerative/inflammatory changes and frequently misclassified as "hepatobiliary cystadenoma." II. Neoplastic (13%); 27 (10.5%) had ovarian-type stroma (OTS) and qualified as mucinous cystic neoplasm (MCN) per World Health Organization (WHO). These were female, solitary, mean age 52, mean size 11 cm, and 2 were associated with carcinoma (1 in situ and 1 microinvasive). There were 3 intraductal papillary neoplasms, 1 intraductal oncocytic papillary neoplasm, 1 cystic cholangiocarcinoma, and 2 cystic metastasis. III. Infectious/inflammatory (12%). These included 23 hydatid cysts (including 2 Echinococcus alveolaris both misdiagnosed preoperatively as cancer), nonspecific inflammatory cysts (abscesses, inflammatory cysts: 3.4%). IV. Congenital (7%). Mostly small (<3 cm); choledochal cyst (5%), foregut cyst (2%). V. Miscellaneous (4%). In conclusion, hepatic cysts occur predominantly in women (3/1), are mostly (90%) non-neoplastic, and seldom (<2%) malignant. Cystic bile duct hamartomas and their relative not otherwise specified-type benign biliary cysts are frequently multifocal and often misdiagnosed as "cystadenoma/carcinoma." Defined by OTS, MCNs (the true "hepatobiliary cystadenoma/carcinoma") are solitary, constitute only 10.5% of hepatic cysts, and have a significantly different profile than the impression in the literature in that essentially all are perimenopausal females, and rarely associated with carcinoma (7%). Since MCNs can only be diagnosed by demonstration of OTS through complete microscopic examination, it is advisable to avoid the term "cystadenoma/cystadenocarcinoma" solely based on radiologic examination, and the following simplified terminology would be preferable in preoperative evaluation to avoid conflicts with the final pathologic diagnosis: (1) noncomplex (favor benign), (2) complex (in 3 subsets, as favor benign, cannot rule out malignancy, or favor malignancy), (3) malignant features.

Incidental liver lesions are increasingly being discovered in the context of the increased use of ultrasound studies and the majority are benign. In children, although individually rare, the differential diagnosis is broad and therefore a systematic approach is of utmost importance to reduce the radiological and disease burden in children and their families. This review article collected current evidence and provides fundamental information for the clinician regarding specific differential diagnoses and unique imaging features of benign liver lesions in children. Ultimately, we propose a practical stepwise approach mainly involving clinical and radiological workup. Laboratory tests and histopathological examination may be necessary in the presence of red flags or in indeterminate lesions.

We describe the case of a 58-year-old female who presented to her primary care provider with lifelong anorexia, 6-week history of liquid only diet and new onset epigastric abdominal pain radiating to the back accompanied by nausea and abdominal distension. An initial computed tomography scan with contrast demonstrated a massive simple hepatic cyst with mass effect compression of the duodenal sweep. Repetitive treatment with aspiration sclerotherapy using hypertonic saline provided initial resolution of symptoms and led to substantial reduction of cyst diameter. Repeat imaging demonstrated complete drainage of the cyst and decompression of the duodenum. Ultimately, the patient's symptoms returned 6 weeks later at which time she opted for surgical deroofing of the cyst. Surgery provided for complete resolution. This case appears to be the first to document the compression of second portion of the duodenum by a massive simple hepatic cyst causing anorexia and mimicking gastric outlet obstruction.

We report a case of inferior vena cava (IVC) thrombosis caused by compression by a giant liver cyst. A 68-year-old man with a 1-day history of abdominal pain was referred to another hospital. Ultrasonography (US) and enhanced computed tomography (CT) showed a multilobular cyst on the right liver lobe that had increased to 300 mm in diameter from 90 mm 18 months earlier. Thrombosis was detected in the IVC, which was compressed by the cyst. Percutaneous transhepatic cyst drainage achieved no significant change in size. Cytological analysis from the percutaneous drainage tube fluid showed no evidence of malignancy. He was referred to our hospital for further assessment and treatment. Enhanced US using perfluorobutane, CT, and magnetic resonance imaging showed no tumorous lesions in the cyst. Thus, we diagnosed it as a multilobular cyst with no evidence of malignancy. A 3-week course of heparin resulted in the successful resolution of the thrombosis. Cystectomy was subsequently performed and pathological examination showed a multifocal cyst consisting of central suppurative inflammatory exudation and hemorrhagic material, with no malignancy. This case demonstrates that giant, expanding, non-tumorous cysts can cause IVC thrombosis. Careful treatment using heparin successfully resolved the thrombosis and allowed successful cystectomy.

Benign focal liver lesions can origin from all kind of liver cells: hepatocytes, mesenchymal and cholangiocellular line. Their features at imaging may sometimes pose difficulties in differential diagnosis with malignant primary and secondary lesions. In particular, the use of MDCT and MRI with extracellular and hepatobiliary Contrast Agents may non invasively help in correct interpretation and definition of hepatocellular or mesenchymal and inflammatory nature, allowing to choose the best treatment option. The peculiarities of main benign liver lesions at US, CT and MRI are described, with special attention to differential diagnosis and diagnostic clues.

Hepatic (biliary) cystic tumor (HBCT) is a rare focal cystic liver lesion, which has been rarely described in the literature. In our current multicenter, retrospective study, we aimed to analyze contrast enhanced ultrasound (CEUS) features and its diagnostic performance in histologically proved HBCT.

Twenty-three patients with single HBCT were retrospectively analyzed. Histologically, 17 (73.9%) were benign hepatic (biliary) cystadenoma (HBCA), 6 (26.1%) were hepatic (biliary) cystadenocarcinoma (HBCAC). All CEUS examinations were assessed by two independent radiologists in consensus. Criteria of CEUS imaging evaluation included the contrast enhancement pattern of lesion (hypoenhancing, hyperenhancing, isoenhancing in comparison to the surrounding liver parenchyma) during the arterial, portal venous and late phases.

After injection of ultrasound contrast agents, most of the HBCTs (78.3%, 18/23) had typical honeycomb enhancement pattern of the cystic wall, septa or mural nodules. Comparing between HBCA and HBCAC, hyperenhancement of the honeycomb septa during the arterial phase was more common in HBCA (p = .047). However, hypoenhancement during the portal venous and late phases was the characteristic of HBCAC (p = .041).

The EFSUMB algorithm for CEUS for characterization of solid focal liver lesions is also applicable to HBCT. CEUS evaluation can avoid further diagnostic investigations or invasive biopsy procedure.