Hepatic Mucinous Cystic Neoplasm Versus Simple Biliary Cyst: Assessment of Distinguishing Imaging Features Using CT and MRI

Classification of intrahepatic cholangiocarcinoma

Cholangiocarcinoma is a heterogenous malignancy with various classifications based on location, morphological features, histological features, and actionable genetic mutations. Intrahepatic cholangiocarcinoma (ICC), which arises in and proximal to second order bile ducts, is the second most common primary liver malignancy after hepatocellular carcinoma. In this review, we will discuss ICC risk factors, precursor lesions, various growth, anatomic, morphologic, and histologic classifications, rare variants, and differential diagnoses.

Benign biliary conditions with increased risk of malignant lesions

Numerous conditions and pathologies affect the biliary system, many of which have underlying benign courses. However, these overall benign conditions can predispose the patient to malignant pathologies, often due to malignancy arising from abnormal biliary ducts (such as with cholangiocarcinoma) or due to malignancy arising from end-stage liver disease caused by the biliary condition (such as with hepatocellular carcinoma). While these malignancies can at times be obvious, some pathologies can be very difficult to detect and distinguish from the underlying benign biliary etiology. This paper discusses various benign biliary pathologies, with discussion of epidemiology, imaging features, malignant potential, and treatment considerations, with the goal of educating radiologists and referring clinicians to the risk and appearance of hepatobiliary malignancies associated with benign biliary conditions.

Rare Malignant Liver Tumors: Current Insights and Imaging Challenges

Rare malignant liver tumors (RMLTs) comprise a diverse group of neoplasms with distinct imaging features and significant diagnostic challenges due to their low prevalence and overlap with more common hepatic lesions. This review highlights the main radiologic characteristics of selected rare malignant liver tumors-including fibrolamellar hepatocellular carcinoma, hepatic lymphoma, hepatocellular carcinoma in non-cirrhotic liver, mucinous cystic neoplasm, intraductal papillary neoplasm of the bile duct, epithelioid hemangioendothelioma, angiosarcoma, malignant hepatic adenoma, neuroendocrine tumor, hepatocholangiocarcinoma, hepatoblastoma, undifferentiated embryonal sarcoma, and infantile hepatic hemangioendothelioma-focusing on their presentation in computed tomography and magnetic resonance imaging. Recognizing specific imaging findings, such as arterial hyperenhancement, biliary communication, target and lollipop signs, and tumor morphology, can help narrow differential diagnoses and guide appropriate clinical management. Despite advancements in imaging, histopathologic confirmation is often required due to nonspecific features. Improved radiologic awareness of these rare entities is essential to facilitate early diagnosis and individualized treatment planning.

Differentiation between mucinous cystic neoplasms and simple cysts of the liver: a systematic review and meta-analysis

PURPOSE

Radiologic examinations frequently identify cystic liver lesions, which encompass various entities from simple benign cysts to malignant neoplasms. This work analyses the available data to compare diagnostic features of biliary cystic neoplasms and hepatic simple cysts.

METHODS

A systematic search of PubMed, Scopus, Embase, and Web of Science up to October 2024 was conducted. The characteristics were categorized into hepatic simple cysts (HSC) and mucinous cystic neoplasms (MCN), including biliary cystadenoma (BCA) and cystadenocarcinoma (BCAC) detected by imaging modalities including ultrasound, CT scans with IV contrast, or MRI. We analyzed biliary cystic neoplasms and hepatic simple cysts across multiple studies using Review Manager Ver. 5, calculating summary measures for each feature.

RESULTS

The study analyzed 577 lesions in 577 patients and 49 studies. Hepatic simple cysts were the most common finding, with 349 identified, mainly in the right hepatic lobe, presented with abdominal pain or incidentally. Intracystic septation was found in 50.1% of HSC lesions, with thick septation in 10.52% of lesions. 228 (49.9%) patients were diagnosed with MCN, with abdominal swelling and pain as the most common presentation. Septation was the most common radiological feature of MCNs, with thick septa in 50.61%. MCNs had internal septa, solid mural nodule, upstream bile duct dilation, presence in the left hepatic lobe, septal thickening, cystic wall enhancement, calcifications, and internal debris. The presence of a cyst in the left lobe was more related to MCNs.

CONCLUSION

Characterizing cystic liver lesions necessitates a comprehensive evaluation of the lesions' location, size, and complexity. Imaging and clinical findings are essential for a final diagnosis.

Refining imaging criteria for mucinous cystic neoplasm of the liver: simplified diagnostic approach

OBJECTIVES

To propose a simplified diagnostic approach for mucinous cystic neoplasm (MCN) of the liver and compare its diagnostic performance with the European Association for the Study of the Liver (EASL) criteria.

METHODS

We conducted a retrospective cohort study of 124 patients with pathologically confirmed lesions (13 MCNs, 111 hepatic cysts) who underwent CT/MRI between January 2016 and January 2023. Two major features (thick septation, nodularity) and five minor features (upstream biliary dilatation, thin septations, internal hemorrhage, perfusion change, < 3 coexistent hepatic cysts) of the EASL criteria were evaluated. For a septa-wall relationship, the angle of indentation was measured, and the optimal angle predicting MCN was determined by receiver operating characteristic curve analysis. Logistic regression identified features predicting MCN, and a modified criteria was developed. The sensitivity, specificity, and accuracy of both criteria were compared using McNemar's test.

RESULTS

The optimal indentation angle was 111°. Absence of indentation or indentation at an angle > 111° (odds ratio (OR), 100.4; 95% confidence interval (CI), 4.9-2076.0) and < 3 coexistent hepatic cysts (OR, 47.8; 95% CI, 1.5-1489.1) were independent features predicting MCN. Our modified criteria used a combination of them and demonstrated greater accuracy (98.4% vs. 92.7%; p = 0.035) than the EASL criteria (a combination of ≥ 1 major and ≥ 1 minor feature[s]), with comparable sensitivity (92.3% vs. 76.9%; p = 0.317) and specificity (99.1% vs. 94.6%; p = 0.059).

CONCLUSION

Our modified criteria using two imaging features may be a promising alternative to current EASL criteria to improve accuracy in diagnosing MCN.

KEY POINTS

Question Radiological diagnosis of mucinous cystic neoplasm of the liver remains challenging due to the lack of specific imaging features, leading to suboptimal treatment decisions. Findings No external indentation or an indentation angle > 111° and fewer than 3 coexistent hepatic cysts are independent factors predicting mucinous cystic neoplasm of the liver. Clinical relevance The simplified approach using these two imaging features for diagnosing mucinous cystic neoplasm of the liver offers improved accuracy and reliability over the 2022 EASL criteria, potentially reducing misdiagnosis and unnecessary surgeries.

Gallbladder and biliary pathology: lessons learned from multidisciplinary conference

The radiologic diagnosis of biliary disease can be challenging due to atypical or delayed presentation, rare or less common entities, and imaging overlap of benign and malignant processes. Establishing a specific diagnosis, when possible, is important to avoid progression of infections to sepsis and multiorgan failure, and for appropriate staging and management in cases of malignancy. Gallstones are the most common biliary disease, and along with stone-related complications, including cholecystitis and choledocholithiasis, constitute the majority of acute biliary pathology. Late and atypical manifestations of acute cholecystitis demonstrate imaging overlap with primary gallbladder cholangiocarcinoma, especially with cases of exuberant inflammatory reaction such as xanthogranulomatous cholecystitis. Additional challenging scenarios related to gallbladder disease, that may be benign or malignant, include adjacent fistulas and lymphadenopathy. Dropped gallstones, especially in atypical locations, may be misdiagnosed as neoplastic. Recurrent cholecystitis after cholecystectomy, whether related to subtotal cholecystectomy or to stumpitis, is another entity that can be confusing to the radiologist with a documented history of cholecystectomy. Inflammatory and autoimmune conditions, such as pseudotumors and IgG4 disease, are a less common but not infrequent cause of diagnostic dilemma. Furthermore, biliary strictures and hepatobiliary cystic lesions can be benign or malignant and could constitute a diagnostic and management challenge. The goal of this manuscript is to present the lessons learned from multidisciplinary conferences on the above entities and suggest tips and pearls to maximize the value of radiologists' contribution to patient management.

Cystic lesions and their mimics involving the intrahepatic bile ducts and peribiliary space: diagnosis, complications, and management

Biliary and peribiliary cystic lesions represent a diverse group of abnormalities, often discovered incidentally during imaging for unrelated conditions. These lesions, typically asymptomatic, necessitate precise imaging modalities to characterize their nature and determine subsequent clinical actions, such as follow-up imaging, biopsy, or surgical referral. The anatomic location of these cystic lesions, whether biliary or peribiliary, influences both diagnostic and prognostic outcomes. Biliary cystic lesions, such as mucinous cystic neoplasms, intraductal papillary neoplasms of the bile duct, and Caroli disease, require careful monitoring due to their propensity to develop malignancy. In contrast, peribiliary cysts are often associated with chronic liver disease and may indicate disease progression through a gradual increase in cyst size. Accurate differentiation of these lesions from other clinical entities that have overlapping features on imaging, such as microabscesses, bilomas, Langerhans cell histiocytosis, neurofibromatosis, and vascular anomalies such as cavernous transformation of the portal vein, is essential given the divergent management for each. This article focuses on intrahepatic biliary and peribiliary cystic lesions and their mimics, highlighting their imaging characteristics with an emphasis on magnetic resonance imaging and magnetic resonance cholangiopancreatography, differential diagnosis, potential associated complications, and clinical management.

WFUMB Review Paper. Incidental Findings in Otherwise Healthy Subjects, How to Manage: Liver

An incidental focal liver lesion (IFLL) is defined as a hepatic lesion identified in a patient imaged for an unrelated reason. They are frequently encountered in daily practice, sometimes leading to unnecessary, invasive and potentially harmful follow-up investigations. The clinical presentation and the imaging aspects play an important role in deciding if, and what further evaluation, is needed. In low-risk patients (i.e., without a history of malignant or chronic liver disease or related symptoms), especially in those younger than 40 years old, more than 95% of IFLLs are likely benign. Shear Wave liver Elastography (SWE) of the surrounding liver parenchyma should be considered to exclude liver cirrhosis and for further risk stratification. If an IFLL in a low-risk patient has a typical appearance on B-mode ultrasound of a benign lesion (e.g., simple cyst, calcification, focal fatty change, typical hemangioma), no further imaging is needed. Contrast-Enhanced Ultrasound (CEUS) should be considered as the first-line contrast imaging modality to differentiate benign from malignant IFLLs, since it has a similar accuracy to contrast-enhanced (CE)-MRI. On CEUS, hypoenhancement of a lesion in the late vascular phase is characteristic for malignancy. CE-CT should be avoided for characterizing probable benign FLL and reserved for staging once a lesion is proven malignant. In high-risk patients (i.e., with chronic liver disease or an oncological history), each IFLL should initially be considered as potentially malignant, and every effort should be made to confirm or exclude malignancy. US-guided biopsy should be considered in those with unresectable malignant lesions, particularly if the diagnosis remains unclear, or when a specific tissue diagnosis is needed.

To identify important MRI features to differentiate hepatic mucinous cystic neoplasms from septated hepatic cysts based on random forest

OBJECTIVE

To identify important MRI features to differentiate hepatic mucinous cystic neoplasms (MCN) from septated hepatic cysts (HC) using random forest and compared with logistic regression algorithm.

METHODS

Pathologically diagnosed hepatic cysts and hepatic MCNs with pre-operative contrast-enhanced MRI in our hospital from 2010 to 2023 were collected and only septated lesions on enhanced MRI were enrolled. A total of 21 septated HC and 18 MCNs were included in this study. Eighteen MRI features were analyzed and top important features were identified based on random forest (RF) algorithm. The results were evaluated by the prediction performance of a RF model combining the important features and compared with the performance of the logistic regression (LR) algorithm. Finally, for each identified feature, diagnostic probability, sensitivity, and specificity were calculated and compared.

RESULTS

Four variables, i.e., the septation arising from wall without indentation, multiseptate, intracapsular cyst sign, and solitary lesion were extracted as top important features with significance for MCNs by the random forest algorithm. The RF model using these variables had an AUC of 0.982 (0.95CI, 0.950-1.000), compared with the LR model based on two identified features with AUC of 0.931 (0.95CI, 0.846-1.000), p = 0.202. Among the four important features, multiseptate had the highest specificity (95.2%) and good sensitivity (72.2%, lower than the septation from wall without indentation, 94.4%) to diagnose MCNs.

CONCLUSION

Four out of 18 MRI features were extracted as reliably important factors to differ hepatic MCNs from septated HC. The combination of these four features in a RF model could achieve satisfactory diagnostic efficacy.

ACG Clinical Guideline: Focal Liver Lesions

Focal liver lesions (FLLs) have become an increasingly common finding on abdominal imaging, especially asymptomatic and incidental liver lesions. Gastroenterologists and hepatologists often see these patients in consultation and make recommendations for management of multiple types of liver lesions, including hepatocellular adenoma, focal nodular hyperplasia, hemangioma, and hepatic cystic lesions including polycystic liver disease. Malignancy is important to consider in the differential diagnosis of FLLs, and healthcare providers must be familiar with the diagnosis and management of FLLs. This American College of Gastroenterology practice guideline uses the best evidence available to make diagnosis and management recommendations for the most common FLLs.

Imaging features and management of focal liver lesions

Notably, the number of incidentally detected focal liver lesions (FLLs) has increased dramatically in recent years due to the increased use of radiological imaging. The diagnosis of FLLs can be made through a well-documented medical history, physical examination, laboratory tests, and appropriate imaging methods. Although benign FLLs are more common than malignant ones in adults, even in patients with primary malignancy, accurate diagnosis of incidental FLLs is of utmost clinical significance. In clinical practice, FLLs are frequently evaluated non-invasively using ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). Although US is a cost-effective and widely used imaging method, its diagnostic specificity and sensitivity for FLL characterization are limited. FLLs are primarily characterized by obtaining enhancement patterns through dynamic contrast-enhanced CT and MRI. MRI is a problem-solving method with high specificity and sensitivity, commonly used for the evaluation of FLLs that cannot be characterized by US or CT. Recent technical advancements in MRI, along with the use of hepatobiliary-specific MRI contrast agents, have significantly improved the success of FLL characterization and reduced unnecessary biopsies. The American College of Radiology (ACR) appropriateness criteria are evidence-based recommendations intended to assist clinicians in selecting the optimal imaging or treatment option for their patients. ACR Appropriateness Criteria Liver Lesion-Initial Characterization guideline provides recommendations for the imaging methods that should be used for the characterization of incidentally detected FLLs in various clinical scenarios. The American College of Gastroenterology (ACG) Clinical Guideline offers evidence-based recommendations for both the diagnosis and management of FLL. American Association for the Study of Liver Diseases (AASLD) Practice Guidance provides an approach to the diagnosis and management of patients with hepatocellular carcinoma. In this article, FLLs are reviewed with a comprehensive analysis of ACR Appropriateness Criteria, ACG Clinical Guideline, AASLD Practice Guidance, and current medical literature from peer-reviewed journals. The article includes a discussion of imaging methods used for the assessment of FLL, current recommended imaging techniques, innovations in liver imaging, contrast agents, imaging features of common nonmetastatic benign and malignant FLL, as well as current management recommendations.

Hepatic hemangioma in a simple liver cyst mimicking biliary cystic neoplasm

BACKGROUND

Follow-up is recommended for an asymptomatic unilocular hepatic cystic lesion without wall-thickness and nodular components. A few liver cystic lesions represent biliary cystic neoplasms, which are difficult to differentiate from simple cysts with benign mural nodules on imaging alone.

CASE PRESENTATION

An 84-year-old woman with a history of simple liver cyst diagnosed one year prior was admitted for evaluation of a developed mural nodule in the cystic lesion. She had no specific symptoms and no abnormalities in blood tests except for carcinoembryonic antigen (5.0 ng/mL) and carbohydrate antigen (43.5 U/mL) levels. Contrast-enhanced computed tomography revealed a well-defined, low-attenuation lesion without a septum that had enlarged from 41 to 47 mm. No dilation of the bile duct was observed. A gradually enhancing mural nodule, 14 mm in diameter, was confirmed. MRI revealed a uniform water-intense cystic lesion with a mural nodule. This was followed by T2-enhanced imaging showing peripheral hypointensity and central hyperintensity. Enhanced ultrasonography revealed an enhanced nodule with a distinct artery within it. A needle biopsy of the wall nodule or aspiration of intracystic fluid was not performed to avoid tumor cell spillage. The possibility of a neoplastic cystic tumor could not be ruled out, so a partial hepatectomy was performed with adequate margins. Pathologically, the cystic lesion contained a black 5 mm nodule consisting of a thin, whitish fibrous wall and dilated vessels lined by CD31 and CD34 positive endothelial cells. The final diagnosis was a rare cavernous hemangioma within a simple liver cyst.

CONCLUSIONS

Cavernous hemangiomas mimicking well-enhanced mural nodules can arise from simple liver cysts. In less malignant cases, laparoscopic biopsy or percutaneous targeted biopsy of the mural nodules, together with needle ablation, may be recommended to avoid unnecessary surgery.

Diagnosis and treatment of patients with suspected mucinous cystic neoplasms of the liver: a retrospective cohort study

PURPOSE

Mucinous cystic neoplasms of the liver (MCN-L) are hepatic cysts with a low malignant potential. The recent European Association for the Study of the Liver (EASL) guidelines provide guidance on the imaging features and surgical management of MCN-L, yet are hampered by a lack of studies adhering to the revised World Health Organization (WHO) criteria. This study attempted to validate the new 2022 EASL-guidelines in a retrospective cohort study of patients who underwent surgery for suspected MCN-L.

METHODS

Patients undergoing surgery for suspected MCN-L in a single center between 2010 and 2020 were included. Imaging features were assessed according to the EASL guidelines and were compared to final pathological diagnoses, according to the WHO criteria.

RESULTS

In total, 35 patients were included. In three patients, there were no worrisome imaging features, yet final pathological diagnosis showed MCN-L. Contrarily, six patients with worrisome imaging features did not have MCN-L. Five patients were diagnosed with MCN-L on final pathology. The sensitivity of the EASL-guidelines for the diagnosis of MCN-L was 40% (95%CI: 5.3-85%) and the specificity was 80% (95% CI: 61-92%).

CONCLUSION

Although the new EASL-guidelines provide some guidance, they could not reliably distinguish MCN-L from other cysts in our series. Thus, preoperative diagnosis of MCN-L remains challenging and we should be careful in selecting surgical strategies based on these criteria.

Management of Mucinous Cystic Neoplasms of the Liver

BACKGROUND

Mucinous cystic neoplasms of the liver (MCN-L) including biliary cystadenomas (BCA) and biliary cystadenocarcinomas (BCAC) are rare cystic lesions that comprise less than 5% of all liver cysts and affect only a small subset of individuals. We herein review the current evidence regarding the clinical presentation, imaging characteristics, tumor markers, pathological findings, clinical management, and prognosis of MCN-L.

METHODS

A comprehensive review of the literature was performed using MEDLINE/Pubmed and Web of Science databases. In PubMed, the terms "biliary cystadenoma," "biliary cystadenocarcinoma," and "non parasitic hepatic cysts" were queried to identify the most recent data on MCN-L.

RESULTS

US imaging, CT, and MRI, as well as consideration of clinicopathological features, are required to appropriately characterize and diagnose hepatic cystic tumors. BCA are premalignant lesions and cannot be reliably differentiated from BCAC based on imaging alone. As such, both types of lesions should be treated with margin-negative surgical resection. Following surgical resection, recurrence is fairly low among patients with BCA and BCAC. Despite having worse long-term outcomes than BCA, the prognosis following surgical resection of BCAC still remains more favorable than other primary malignant liver tumors.

CONCLUSION

MCN-L are rare cystic liver tumors that include BCA and BCAC, which can be difficult to differentiate based on imaging alone. Surgical resection remains the mainstay of management for MCN-L with recurrence being generally uncommon. Future multi-institutional studies are still required to better understand the biology behind BCA and BCAC to improve the care of patients with MCN-L.

External validation of a machine learning based algorithm to differentiate hepatic mucinous cystic neoplasms from benign hepatic cysts

PURPOSE

To externally validate an algorithm for non-invasive differentiation of hepatic mucinous cystic neoplasms (MCN) from benign hepatic cysts (BHC), which differ in management.

METHODS

Patients with cystic liver lesions pathologically confirmed as MCN or BHC between January 2005 and March 2022 from multiple institutions were retrospectively included. Five readers (2 radiologists, 3 non-radiologist physicians) independently reviewed contrast-enhanced CT or MRI examinations before tissue sampling and applied the 3-feature classification algorithm described by Hardie et al. to differentiate between MCN and BHC, which had a reported accuracy of 93.5%. The classification was then compared to the pathology results. Interreader agreement between readers across different levels of experience was evaluated with Fleiss' Kappa.

RESULTS

The final cohort included 159 patients, median age of 62 years (IQR [52.0, 70.0]), 66.7% female (106). Of all patients, 89.3% (142) had BHC, and the remaining 10.7% (17) had MCN on pathology. Agreement for class designation between the radiologists was almost perfect (Fleiss' Kappa 0.840, p < 0.001). The algorithm had an accuracy of 98.1% (95% CI [94.6%, 99.6%]), a positive predictive value of 100.0% (95% CI [76.8%, 100.0%]), a negative predictive value of 97.9% (95% CI [94.1%, 99.6%]), and an area under the receiver operator characteristic curve (AUC) of 0.911 (95% CI [0.818, 1.000]).

CONCLUSION

The evaluated algorithm showed similarly high diagnostic accuracy in our external, multi-institutional validation cohort. This 3-feature algorithm is easily and rapidly applied and its features are reproducible among radiologists, showing promise as a clinical decision support tool.

Imaging of Hepatobiliary Cancer

The liver and biliary tree are common sites of primary and secondary malignancies. MRI followed by CT is the mainstay for the imaging characterization of these malignancies with the dynamically acquired contrast enhanced phases being the most important for diagnosis. The liver imaging reporting and data system classification provides a useful framework for reporting lesions in patents with underlying cirrhosis or who are at high risk for developing hepatocellular carcinoma. Detection of metastases is improved with the use of liver specific MRI contrast agents and diffusion weighted sequences. Aside from hepatocellular carcinoma, which is often diagnosed noninvasively, other primary hepatobiliary tumors may require biopsy for definite diagnosis, especially when presenting with nonclassic imaging findings. In this review, we examine the imaging findings of common and less common hepatobiliary tumors.

Hepatobiliary mucinous cystic neoplasms and mimics

This review will provide an overview of hepatobiliary mucinous cystic neoplasms and their mimics such as complex appearing benign cysts, intraductal papillary neoplasm of bile ducts, choledochal cysts, infectious cysts, and other cystic neoplasms. Preoperative imaging, particularly abdominal MRI with MRCP, plays a key role in differentiating these entities which differ widely in management. Familiarity with the differentiating imaging features of mucinous cystic neoplasms and their mimics allows radiologists to provide management-guiding reports.

Mucinous Cystic Neoplasms of the Liver: Epidemiology, Diagnosis, and Management

Mucinous cystic neoplasms (MCNs) are rare tumors of the liver, occasionally seen in the biliary tree. Epidemiologic data are limited by their indolence and recent changes to diagnostic criteria. They are considered premalignant lesions capable of invasive behavior. While their etiology remains unknown, their female predominance, age of onset, and hormonally responsive ovarian-type stroma suggest ectopic organogenesis during embryologic development. MCNs can typically be recognized on imaging; yet, invasiveness is often indeterminate, and percutaneous tissue biopsy has shown limited value. Therefore, complete excision is recommended for all lesions as focal malignant transformation and metastatic disease has been reported.

Mucinous cystic neoplasms of the liver with biliary prolapse

Objectives

To describe the prevalence, clinical and radiological findings of biliary prolapse in pathologically proven mucinous cystic neoplasm of the liver (MCN-L).

Methods

Thirty-four patients, all female with median age 50 years (range, 14–82), with histologically confirmed MCN-L were enrolled. Median tumor size was 9 cm (range, 2–21 cm). Fifty-seven examinations (17 ultrasound, 25 CT, and 15 MR) among 34 MCN-Ls were reviewed. Two radiologists retrospectively assessed images for tumor location, size and other morphological features of the tumor, presence of biliary prolapse and upstream bile duct dilatation. Ultrasound, CT, and MR were assessed separately. Clinical features were evaluated. Clinical and radiological characteristics of MCN-L with and without biliary prolapse were compared.

Results

15% (5/34) of MCN-Ls showed biliary prolapse confirmed at pathology. None of MCN-Ls were associated with invasive carcinoma. Patients with biliary prolapse were significantly younger than those without (median 27 years [22–56] vs. median 51 years [14–82], p = 0.03). MCN-Ls with biliary prolapse were significantly smaller than those without (median 6.4 cm [2.2–7.5] vs. median 9.6 cm [3.1–21], p = 0.01). The upstream bile duct was dilated more frequently in MCN-Ls with biliary prolapse (100% vs. 38%, p = 0.02). Jaundice was significantly more common in MCN-Ls with biliary prolapse (80 vs 3%, p = 0.0005). Other clinical or radiological features were not significantly different between two groups.

Conclusions

Biliary prolapse was found in 15% of MCN-Ls. MCN-Ls with biliary prolapse were significantly smaller and were more commonly associated with upstream bile duct dilation and jaundice than those without biliary prolapse.

Liver Mucinous Cystic Neoplasm With Obstructive Jaundice

Biliary mucinous cystic neoplasms (BMCNs) are rare and slow-growing lesions that are usually discovered incidentally. They can imitate various other liver tumors. Here, we present a 31-year-old female patient who presented with complaints of abdominal pain, nausea, shortness of breath, and obstructive jaundice. Ultrasound showed a large, lobulated, cystic liver mass. Abdominal computed tomography (CT) scan showed features suggestive of a hydatid cyst or complicated liver cyst. A laparoscopic deroofing was performed and showed a liver cyst involving segments 2, 3, 4A, and 4B. Histopathology showed that the cyst wall was lined by columnar mucin-producing epithelium with multifocal areas of ovarian-like stroma, and the diagnosis of biliary mucinous cystic neoplasms was made. A one-year, follow-up radiological examination did not show any recurrence. BMCNs are quite rare. The nonspecific nature of the symptoms and radiological characteristics makes the diagnosis of BMCN challenging. Imaging modalities can aid in the diagnosis, but pathological examination is essential in confirming a definite diagnosis.

EASL Clinical Practice Guidelines on the management of cystic liver diseases

The advent of enhanced radiological imaging techniques has facilitated the diagnosis of cystic liver lesions. Concomitantly, the evidence base supporting the management of these diseases has matured over the last decades. As a result, comprehensive clinical guidance on the subject matter is warranted. These Clinical Practice Guidelines cover the diagnosis and management of hepatic cysts, mucinous cystic neoplasms of the liver, biliary hamartomas, polycystic liver disease, Caroli disease, Caroli syndrome, biliary hamartomas and peribiliary cysts. On the basis of in-depth review of the relevant literature we provide recommendations to navigate clinical dilemmas followed by supporting text. The recommendations are graded according to the Oxford Centre for Evidence-Based Medicine system and categorised as 'weak' or 'strong'. We aim to provide the best available evidence to aid the clinical decision-making process in the management of patients with cystic liver disease.

Imaging Features of Premalignant Biliary Lesions and Predisposing Conditions with Pathologic Correlation

Biliary malignancies include those arising from the intrahepatic and extrahepatic bile ducts as well as the gallbladder and hepatopancreatic ampulla of Vater. The majority of intrahepatic and extrahepatic malignancies are cholangiocarcinomas (CCAs). They arise owing to a complex interplay between the patient-specific genetic background and multiple risk factors and may occur in the liver (intrahepatic CCA), hilum (perihilar CCA), or extrahepatic bile ducts (distal CCA). Biliary-type adenocarcinoma constitutes the most common histologic type of ampullary and gallbladder malignancies. Its prognosis is poor and surgical resection is considered curative, so early detection is key, with multimodality imaging playing a central role in making the diagnosis. There are several risk factors for biliary malignancy as well as predisposing conditions that increase the risk; this review highlights the pertinent imaging features of these entities with histopathologic correlation. The predisposing factors are broken down into three major categories: (a) congenital malformations such as choledochal cyst and pancreaticobiliary maljunction; (b) infectious or inflammatory conditions such as parasitic infections, hepatolithiasis, primary sclerosing cholangitis, and porcelain gallbladder; and (c) preinvasive epithelial neoplasms such as biliary intraepithelial neoplasm, intraductal papillary neoplasm of the bile duct, intra-ampullary papillary tubular neoplasm, and intracholecystic papillary neoplasm of the gallbladder. Recognizing the baseline features of these premalignant biliary entities and changes in their appearance over time that indicate the advent of malignancy in high-risk patients can lead to early diagnosis and potentially curative management. An invited commentary by Volpacchio is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Hepatic Cysts: Reappraisal of the Classification, Terminology, Differential Diagnosis, and Clinicopathologic Characteristics in 258 Cases

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.

Pure Laparoscopic Left Hepatectomy for Regrowth of Mucinous Cystic Neoplasm of the Liver after Laparoscopic Deroofing

Background

Hepatic cystic lesions are common entities, most of which are simple hepatic cysts (SHCs). Mucinous cystic neoplasm of the liver (MCN-L) is a rare tumor characterized by ovarian-like stroma and accounts for <5% of all hepatic cysts. Distinguishing between SHCs and MCN-L is challenging because of the similarity in their imaging findings. Herein, we report a rare regrowth case of MCN-L after laparoscopic deroofing, treated with pure laparoscopic left hepatectomy. Case Presentation. A 63-year-old woman with a large hepatic cystic lesion and abdominal pain was referred to our hospital for surgical treatment. Computed tomography (CT) showed cystic lesions with septations arising from macrolobulations in the left medial segment. She underwent laparoscopic deroofing based on the diagnosis of SHCs; however, the final histopathological diagnosis was MCN-L. She chose observational follow-up, and MCN-L regrowth was detected on follow-up CT 6 months after the laparoscopic deroofing. We performed pure laparoscopic left hepatectomy for complete resection of the MCN-L. She had an uneventful postoperative course and no recurrence at the 5-year follow-up after the radical resection of the MCN-L.

Conclusion

MCN-L is a rare entity, and accurate diagnosis with imaging modalities is greatly challenging. Laparoscopic hepatectomy for MCN-L should be considered as a strong alternative to secure safety and curability.

Complete resection for a giant recurrent biliary cystadenoma: A surgical case report and review of literature

Background

Biliary cystadenoma is a rare cystic neoplasm of the liver. The clinical signs and symptoms are nonspecific, and treatment strategy is variable.

Case presentation

In this study, we presented a case of a 32-year-old female with multilocular biliary cystadenoma. The patient underwent partial removal of the hepatic cyst two times in two different hospitals for two years and that the histopathological results were biliary cystic adenoma but was successfully treated by radical resection after the second recurrence. The patient underwent a J-shaped laparotomy. The giant cystic mass measuring 20 cm × 15 cm was below the position of the right anterior segment. This lesion pushed the liver parenchyma to both sides and compressed the hepatic hilum, causing dilatation of the intrahepatic bile ducts. The patient underwent complete resection of cystic mass. During the dissection, a 0.5mm-diameter fistula of left hepatic duct with the cyst was found. It was sutured using absorbable polydioxanone (PDS 6.0) and the cystic duct tube (C tube) (6 Fr) was inserted via the cystic duct into the left hepatic duct due to drain the bile fluid.

Discussion

A biliary cystadenoma (BCA) primary origin is occasionally rare. Although imaging modalities such as ultrasound, computed tomography and magnetic resonance imaging could be suggestive, however, the definitive diagnosis is depended on the histological examination. Despite of being a benign tumor, it has a high risk of recurrence after conservative treatment. The potential risk for malignant is also present. Therefore, complete resection of the tumors is the treatment of choice.

Conclusion

We herein present a report of a rare case with had a giant biliary cystadenoma (BCA) primary origin. This report aims to improve the understanding of the diagnosis and management of this uncommon disease.

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A biliary cystadenoma (BCA) primary origin is occasionally rare, the clinical manifestations are variable and non-specific.

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BCA should be suspected when there is a multilocular and thick-walled cystic on liver imaging modalities.

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Histological examination and immunohistochemistry staining are considered as the gold standard.

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Radical surgery (enucleation or liver resection) must be still the most effective and major treatment approach.

A case of hepatic intraductal papillary neoplasm of the bile duct

In this report, we present a 57-year-old female with a history of mild alcoholic liver disease during a medical check-up. Abdominal computed tomography and magnetic resonance imaging showed a multicystic mass with a solid enhancing mural nodule in the right lobe of the liver. Subsequently, laparoscopic right liver lobectomy was performed and pathological findings revealed intraductal papillary neoplasm of the bile duct (IPNB) with an associated invasive carcinoma. IPNB is a relatively rare disease that should be considered in the differential diagnosis of hepatic cystic tumours. Our case report highlights the importance of capturing image findings of the IPNB as this disease has a high potential for malignancy.

Mucin-producing Cystic Hepatobiliary Neoplasms: Updated Nomenclature and Clinical, Pathologic, and Imaging Features

Cystic hepatobiliary neoplasms with mucin-producing epithelium-mucinous cystic neoplasm of the liver (MCN) and intraductal papillary neoplasm of the bile duct (IPNB)-are rare and distinct entities that have unique clinical, pathologic, and imaging features. They are differentiated pathologically by the presence of subepithelial ovarian-like hypercellular stroma (OLS), which is the defining histopathologic feature of MCN. MCN is commonly a benign, large, solitary, symptomatic, multiloculated cystic mass without biliary communication that occurs in middle-aged women. On the other hand, IPNBs are a heterogeneous spectrum of tumors, which are commonly associated with invasive carcinoma, occur in older patients, and can be differentiated from MCN by communication with the biliary tree, intraductal masses, associated biliary ductal dilatation, and absent OLS. Understanding of these rare neoplasms has grown and evolved over time and continues to today, but uncertainty and controversy persist, related to the rarity of these tumors, relatively recent designation as separate entities, inherent clinicopathologic heterogeneity, overlapping imaging features, and the fact that many prior studies likely included MCN and cystic IPNB together as a single entity. Confusion regarding these neoplasms is evident by historical inconsistencies and nonstandardized nomenclature through the years. Awareness of these entities is important for the interpreting radiologist to suggest a particular diagnosis or generate a meaningful differential diagnosis in the appropriate setting, and is of particular significance as MCN and cystic IPNB have overlapping imaging features with other more common hepatobiliary cystic masses but have different management and prognosis. Online supplemental material is available for this article. Work of the U.S. Government published under an exclusive license with the RSNA.

Mucinous Cystic Neoplasm of the Cystic Duct: A Rare Location of a Rare Entity

Mucinous cystic neoplasms (MCNs) are uncommon cystic lesions that arise in the liver and biliary system (MCN-LBS) and the pancreas (MCN-P) and rarely arise from the extrahepatic biliary system. Histologically, these lesions are defined by the presence of variably mucin-producing epithelium with ovarian-like, hypercellular mesenchymal stroma. Herein, we present a case of extrahepatic MCN-LBS in a 51-year-old woman. This lesion arose from the cystic duct and was removed via laparoscopic cholecystectomy. Histologic examination confirmed the diagnosis. To our knowledge, this is the third case report of an MCN-LBS arising from the cystic duct in the English literature. In this article, we review clinical and histologic characteristics of MCNs and present two other reports of MCN-LBS of the cystic duct.