Differential diagnosis of complex liver cysts....Page 2 of 20 Learning objectives To describe the...

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Differential diagnosis of complex liver cysts.

Poster No.: C-0801

Congress: ECR 2014

Type: Educational Exhibit

Authors: S. claret loaiza, C. de la Torre, L. Renza Lozada, M. C. CañeteMoslero; Malaga/ES

Keywords: Abdomen, CT-High Resolution, Ultrasound, Diagnostic procedure,Image verification

DOI: 10.1594/ecr2014/C-0801

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Learning objectives

To describe the radiological findings complex liver cysts and correlate them with theepidemiological data, clinical manifestations and laboratory findings in order to make anaccurate diagnosis.

Background

The most representative cases of IP occurred in our hospital during the period 1 Sept/12-1Sept/13 are shown.

A revision of the clinical history and the histopathological findings was made in each case.

Findings and procedure details

Complex cysts are fluid-containing hepatic lesions with one or more of the followingfeatures: wall thickening or irregularity, septation, internal nodularity, enhancement,calcification, and hemorrhagic or proteinaceous contents (Fig.1).

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Fig. 1: Characteristics of simple cyst and complex cyst.References: - Malaga/ES

Because a broad range of disease processes can result in complex cystic liver lesions,they may be further grouped as neoplastic, inflammatory or infectious, and othermiscellaneous entities (Fig. 2).

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Fig. 2: Classification of complex cysts.References: - Malaga/ES

A careful evaluation of particular imaging features as well as associated radiologic andclinical and laboratory findings is necessary to suggest a specific diagnosis.

Neoplastic

Biliary cystadenoma and biliary cystadenocarcinoma- are premalignant

and malignant cystic biliary ductal neoplasms, respectively, that account for fewer than5% of intrahepatic cystic lesions of biliary origin. They arise mainly from the intrahepaticducts and rarely from the extrahepatic ducts or gallbladder. These neoplasms are mostfrequently found within the right lobe of the liver (55%). Biliary cystadenoma presentspredominantly in middle-aged white women with abdominal pain, nausea, vomiting, andobstructive jaundice.

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The characteristic CT appearance is a solitary complex cystic mass with a well-definedthick fibrous capsule, internal septations, and mural nodularity (Fig. 3).

Fig. 3: Biliary cystadenoma. Axial CT images show a solitary complex cystic mass witha well-defined thick fibrous capsule and internal septations.References: - Malaga/ES

The key difference between biliary cystadenoma or biliary cystadenocarcinoma and ahemorrhagic or infected hepatic cyst is that the capsule, internal septations, and muralnodules show contrast enhancement in the former and do not in the latter. It is generallytaught that mural nodules or polypoid, pedunculated excrescences are more common inbiliary cystadenocarcinoma than in biliary cystadenoma.

Imaging characteristics cannot definitely distinguish biliary cystadenoma from biliarycystadenocarcinoma. Therefore, the optimal management of these masses is surgicalresection.

Cystic metastases- Hepatic metastases may appear cystic either due to necrosis andcystic degeneration of rapidly growing hypervascular tumors (sarcoma, melanoma,carcinoid, neuroendocrine tumors, and some lung and breast tumors) or as amanifestation of mucinous colonic or ovarian adenocarcinomas.

On image findings, cystic metastases appear as solitary or, more commonly, multifocallesions with complex features, such as thick, irregular, enhancing walls; thick or nodularseptations; mural nodularity; or internal debris (Fig. 4).

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Fig. 4: Hepatic cystic metastases. Multiple hypodense hepatic masses represent colonmetastases with internal cystic change due to necrosis.References: - Malaga/ES

A clinical history of a known primary malignancy, particularly in the setting of multifocallesions, may help to suggest the diagnosis of cystic hepatic metastases, which can beconfirmed with imaging-guided biopsy.

Cavernous hemangioma- Giant cavernous hemangioma is another primary hepaticneoplasm that can outgrow its blood supply and show central cystic degeneration. Thistumor frequently occurs in middle-aged women.

At ultrasound, giant cavernous hemangioma with central cystic necrosis may sharesome features with more typical hemangiomas, such as a well-circumscribed echogenicperiphery with a hypoechoic center ("reverse target" sign). However, the appearance maynot be diagnostic.

The central cystic component appears hypodense on unenhanced CT and on all phasesof contrast-enhanced dynamic examination (Fig. 5).

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Fig. 5: Cavernous hemangioma.Initial CT scan after bolus injection of contrast materialshows low-attenuation lesion in posterior segment of right lobe of liver. Delayed CTscans show progressive peripheral nodular enhancement of lesion.References: - Malaga/ES

On contrast-enhanced CT and MRI, even hemangiomas with predominantly cysticcomponents continue to show the characteristic peripheral nodular enhancement patternthat helps make the diagnosis. Symptomatic large lesions may require surgical resection.

Inflammatory or Infectious Cysts

Abscess- A hepatic abscess is a localized collection of pus in the liver, with associateddestruction of the hepatic parenchyma and stroma. Hepatic abscesses may be furtherclassified as pyogenic, amebic, or fungal. Because amebic abscesses do not requiredrainage, it is important to distinguish them from pyogenic abscess, which can beestablished on the basis of clinical, radiologic, and serologic data.

Pyogenic abscesses most commonly occur as complications of ascending cholangitisor portal phlebitis. Common causative organisms include Escherichia coli, Clostridiaspecies, Staphylococcus aureus, and Bacteroides species. Clinically, pyogenicabscesses usually manifest in middle-aged or elderly patients who present with fever,right upper and lower quadrant pain, tender hepatomegaly, and elevated WBC counts.On CT, these abscesses appear as well-defined hypoattenuating masses (0-45 HU)with peripheral rim enhancement after the administration of IV contrast material. Acharacteristic CT finding is the "cluster of grapes" sign, which represents the coalescenceof small pyogenic abscesses into a single large multiloculated cavity (Fig. 6).

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Fig. 6: Hepatic abscess. US and axial CT images shoe the "cluster of grapes" sign.References: - Malaga/ES

The presence of gas within an abscess may be due to infection by gas-forming organismssuch as Clostridia species and is strong evidence for pyogenic rather than amebicabscess. The "double target" sign (hypodense rim, isodense periphery, and decreasedattenuation in the center) is also characteristic of complex pyogenic abscess. Thetreatment of pyogenic abscesses includes antibiotic therapy and percutaneous drainage.

Amebic liver abscesses, caused by Entameba histolytica, are the most frequentextracolonic complication of amebiasis. Clinically, in addition to tender hepatomegaly,right upper quadrant abdominal pain, and diarrhea, patients with amebic abscesses oftenhave a history of travel to an endemic area and positive amebic serology. The radiologicfeatures of amebic and pyogenic abscesses often overlap, necessitating clinical andserologic data for diagnosis.

Fungal abscesses due to Candida species are seen in immune-compromised patients.CT shows multiple low-attenuation lesions, which typically have rim enhancement andoften also involve the spleen.

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Echinococcal cysts- Hepatic echinococcosis, or hydatid disease, is caused by the larvalstage of the tapeworm Echinococcus granulosis (more common) or E. multilocularis(more aggressive). After the patient ingests eggs of E. granulosis or E. multilocularisby eating contaminated food or by contact with dog excrement, the larvae invade theintestinal wall and gain access to the liver (via the portal vein), where they develop intohepatic hydatid cysts.

Each hydatid cyst consists of an outer pericyst (compressed and fibrotic host liver tissue),middle laminated membrane or ectocyst, and inner germinal layer. Together, the middlelaminated membrane and inner germinal layer are referred to as the endocyst. Daughtercysts develop on the periphery as a result of germinal layer invagination (Fig. 7).

Fig. 7: Biologic cycle of Echinococcus granulosus and histopathologic analysis ofhidatid cyst.References: - Malaga/ES

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Clinically, echinococcal cysts are predominantly seen in middle-aged patients whopresent with right upper quadrant abdominal pain and jaundice. Key laboratory andclinical features that can distinguish an echinococcal cyst from other cystic liver lesionsare eosinophilia, positive serology and Casoni skin test (seen in 25% of patients), anda history of travel within an endemic areas (Mediterranean basin and sheep-raisingcountries).

On CT, hydatid cysts appear as large unilocular or multilocular hypoattenuating livercysts. One half of them have crescentic mural calcifications. Daughter cysts are seen asround peripheral structures that may have lower attenuation than fluid within the mothercyst. In the absence of daughter cysts, it may be difficult to differentiate an echinococcalcyst from a cystic metastasis or pyogenic abscess radiographically without clinical andserologic data.

On ultrasound, E. granulosis infection typically appears as a multiseptate cyst withdaughter cysts and echogenic material between them (Fig. 8).

Fig. 8: Hidatid cyst. US images show a multiseptate cyst with daughter cysts andechogenic material between them. Axial CT images demostrate two unilocularhypoattenuating liver cysts with peripheral calcifications.

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References: - Malaga/ES

Complications of hydatid cysts include bile duct compression and rupture into the biliarytree with resulting cholangitis. Treatment strategies include medical therapy (albendazoleor mebendazole), drainage or surgical resection, or even liver transplantation.

Postraumatic and Miscellaneous Cysts

Hepatic hematoma-Intrahepatic or perihepatic hematomas usually develop secondary tosurgery, trauma, or hemorrhage within a solid liver neoplasm (especially HCC). Clinically,these lesions may produce signs and symptoms related to blood loss, peritoneal irritation,right upper quadrant tenderness, and guarding.

On CT, a hepatic hematoma is a fluid collection within the liver that has a higherattenuation value than pure fluid in the acute or subacute setting but an attenuation valueidentical to pure fluid in chronic cases (Fig. 9).

Fig. 9: Intrahepatic hematoma in 36-year-old man who sustained blunt trauma toabdomen 2 weeks previously. CT scan shows well-circumscribed area of hypodensityin right lobe of liver.References: - Malaga/ES

Biloma-A biloma is an encapsulated collection of bile outside the biliary tree. It candevelop spontaneously, be secondary to trauma, or represent an iatrogenic complicationafter an interventional procedure or surgery. Leakage of bile within the liver parenchymainduces an inflammatory response, which may result in the formation of a well-definedpseudocapsule.

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On CT and MRI, a biloma appears as a well-defined or slightly irregular cystic lesionwithout septations, calcifications, or a true capsule (Fig. 10).

Fig. 10: Intrahepatic biloma in 40-year-old woman who had sustained blunt abdominaltrauma. Axial and coronal CT images show well-circumscribed fluid-density collectionwithin liver.References: - Malaga/ES

On ultrasound, a biloma is seen as a focal fluid collection within the liver that is situatedclose to the biliary tree and has no vascularity within the lesion.

The management of bilomas includes percutaneous drainage of the fluid collection andERCP with stent placement to improve biliary drainage and prevent further bile leakage.

Images for this section:

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Fig. 1: Characteristics of simple cyst and complex cyst.

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Fig. 2: Classification of complex cysts.

Fig. 3: Biliary cystadenoma. Axial CT images show a solitary complex cystic mass witha well-defined thick fibrous capsule and internal septations.

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Fig. 4: Hepatic cystic metastases. Multiple hypodense hepatic masses represent colonmetastases with internal cystic change due to necrosis.

Fig. 5: Cavernous hemangioma.Initial CT scan after bolus injection of contrast materialshows low-attenuation lesion in posterior segment of right lobe of liver. Delayed CT scansshow progressive peripheral nodular enhancement of lesion.

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Fig. 6: Hepatic abscess. US and axial CT images shoe the "cluster of grapes" sign.

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Fig. 7: Biologic cycle of Echinococcus granulosus and histopathologic analysis of hidatidcyst.

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Fig. 8: Hidatid cyst. US images show a multiseptate cyst with daughter cystsand echogenic material between them. Axial CT images demostrate two unilocularhypoattenuating liver cysts with peripheral calcifications.

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Fig. 9: Intrahepatic hematoma in 36-year-old man who sustained blunt trauma toabdomen 2 weeks previously. CT scan shows well-circumscribed area of hypodensity inright lobe of liver.

Fig. 10: Intrahepatic biloma in 40-year-old woman who had sustained blunt abdominaltrauma. Axial and coronal CT images show well-circumscribed fluid-density collectionwithin liver.

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Conclusion

Complex cysts liver lesions are relatively common. A careful evaluation of particularimaging features as well as associated radiologic and clinical and laboratory findings isnecessary to suggest a specific diagnosis.

Personal information

- S. Claret Loaiza, Department of Radiology, Hospital Carlos Haya, Av Carlos Haya s/n, Málaga (España).

- C. de la Torre, Department of Radiology, Hospital Carlos Haya, Av Carlos Haya s/n,Málaga (España).

- L. Renza, Department of Radiology, Hospital Carlos Haya, Av Carlos Haya s/n, Málaga(España).

- M.C. Cañete Moslero, Department of Radiology, Hospital Carlos Haya, Av Carlos Hayas/n, Málaga (España).

References

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2. Del Poggio P, Buonocore M. Cystic tumors of the liver: a practical approachWorld J Gastroenterol 2008; 14:3616-3620.

3. Ghai S, Dill-Macky M, Wilson S, Haider M. Fluid-fluid levels in cavernoushemangiomas of the liver: baffled? AJR 2005; 184[3 suppl]:S82-S85.

4. Mortele KJ, Ros PR. Cystic focal liver lesions in the adult: differential CT andMR imaging features. RadioGraphics 2001; 21:895-910.

5. Murphy BJ, Casillas J, Ros PR, Morillo G, Albores-Saavedra J, Rolfes DB.The CT appearance of cystic masses of the liver. RadioGraphics 1989;9:307-322.

6. Singh Y, Winick AB, Tabbara SO. Multiloculated cystic liver lesions: radio-pathologic differential diagnosis. RadioGraphics 1997; 17:219-224.

7. Xu AM, Xian ZH, Zhang SH, Chen XF. Intrahepatic cholangiocarcinomaarising in multiple bile duct hamartomas: report of two cases and review ofthe literature. Eur J Gastroenterol Hepatol 2009; 21:580-584.

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