Hepatic Cyst

Published on 20/07/2015 by admin

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Last modified 22/04/2025

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Simple hepatic or bile duct cyst

• Often multiple: Usually < 10

When > 10, consider autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas

• Sharply defined margins, thin walls

• Water density (-10 to +10 HU)

• Usually no or few thin septations

No mural nodularity or wall calcification

• Hemorrhage into cyst may simulate tumor

No enhancement of “solid” material

Varied MR signal intensity (due to mixed blood products)

• US: Anechoic mass, accentuated through transmission

Smooth borders; thin or invisible wall

• Size varies from few mm to > 20 cm

Rarely are the cysts of similar size

Helps to differentiate from biliary hamartomas, which are all usually < 15 mm

TOP DIFFERENTIAL DIAGNOSES

• AD polycystic disease, liver

• Cystic or necrotic metastases

• Biliary cystadenocarcinoma

• Biliary hamartomas

• Ciliated hepatic foregut cyst

• Hepatic cavernous hemangioma

• Biloma

• Hepatic pyogenic abscess

• Hydatid (echinococcal) disease

DIAGNOSTIC CHECKLIST

• Sonography shows cyst morphology better than CT

(Left) Axial CECT shows a spherical hepatic mass with water density and homogeneous contents. No internal debris or wall irregularities are present. This is a classic simple cyst.

(Left) Axial CECT shows a spherical hepatic mass with water density and homogeneous contents. No internal debris or wall irregularities are present. This is a classic simple cyst.

(Right) Ultrasound in the same patient shows an anechoic mass with accentuated through-transmission . Either CT or US would have been sufficient to establish the diagnosis in this patient.

(Right) Ultrasound in the same patient shows an anechoic mass with accentuated through-transmission . Either CT or US would have been sufficient to establish the diagnosis in this patient.

(Left) Axial T1WI MR shows a large, cystic, hepatic mass that has homogeneous low intensity and several thin septa .

(Left) Axial T1WI MR shows a large, cystic, hepatic mass that has homogeneous low intensity and several thin septa .

(Right) Coronal T2WI shows uniform high intensity and septa . The cyst has remained stable for years, and no other evaluation or intervention was performed.

(Right) Coronal T2WI shows uniform high intensity and septa . The cyst has remained stable for years, and no other evaluation or intervention was performed.

TERMINOLOGY

Synonyms

• Simple hepatic or bile duct cyst

Definitions

• Benign, congenital, developmental lesion derived from biliary endothelium

IMAGING

General Features

• Best diagnostic clue

Anechoic lesion with increased through-transmission and no mural nodularity on US

• Location

Any location within liver

• Size

Varies from few mm to > 20 cm

– Rarely are the cysts of similar size

– Helps to differentiate from biliary hamartomas, which are all usually < 15 mm

• Morphology

Spherical or oval, well marginated

• Key concepts

Classified based on etiology and pathogenesis

Congenital or developmental: Simple hepatic or bile duct cyst

– Often multiple: Usually < 10

– No communication with bile ducts

When > 10 in number, fibropolycystic disease must be considered

– i.e., autosomal dominant polycystic liver disease (ADPLD) or biliary hamartomas

CT Findings

• NECT

Simple liver or bile duct cyst

– Sharply defined margins; thin walls

– Water density (-10 to +10 HU)

– Usually no septations (uncommonly ≥ 1 thin septa)

– No fluid-debris levels

– No mural nodularity or wall calcification

Hemorrhage into cyst may be indistinguishable from tumor

– Mural nodularity, fluid-debris level

– No enhancement of “solid” material

• CECT

Simple cyst

– Uncomplicated or complex

No enhancement of cyst contents

MR Findings

• Simple hepatic cyst

T1WI: Hypointense

Heavily T2WI

– Markedly increased signal intensity due to pure fluid content

– Sometimes indistinguishable from hemangioma

• Complicated (hemorrhagic) cyst

T1WI and T2WI

– Higher signal intensity (due to mixed blood products)

– may or may not show fluid level

• T1 C+

Uncomplicated or complicated cyst

– No enhancement of contents

• MRCP

Shows no communication with bile ducts

Ultrasonographic Findings

• Grayscale ultrasound

Uncomplicated simple cyst

– Anechoic mass; accentuated through transmission

– Smooth borders; thin or invisible wall

– No or few septations

– No mural nodules or wall calcification

Hemorrhagic or infected hepatic cyst

– Septations, internal debris

– Thickened wall

– ± calcification

Nonvascular Interventions

• Cyst aspiration may be helpful in confirming infected or hemorrhagic cyst

Imaging Recommendations

• Best imaging tool

Ultrasound, CT, or MR

• Protocol advice

CT or MR should include unenhanced and contrast-enhanced series

Obtain thin axial CT sections to minimize partial volume averaging and to facilitate multiplanar reformations

DIFFERENTIAL DIAGNOSIS

AD Polycystic Disease, Liver

• Hepatic cysts are multiple, of varying sizes, enlarge and distort liver

• Often have contents of complex fluid due to prior hemorrhage

• Cysts in other organs (50% have renal polycystic disease) ± family history of polycystic disease

Cystic or Necrotic Metastases

• Most common with sarcoma metastases and gastrointestinal stromal tumor (GIST)

Especially likely to resemble cysts after chemotherapy

• Enhancing mural nodules, thick septa

• Complex contents, more evident on MR/US than CT

Biliary Cystadenocarcinoma

• Usually large and solitary mass in older woman

• Homogeneous, hypodense, water-density mass

• Almost always has septations and mural nodularity

Rarely nonseptate; these are difficult to distinguish from cysts

Biliary Hamartomas

• Multiple, usually all < 15 mm in diameter

• Often have fibrous nodules in walls

Therefore, echogenic on US

Ciliated Hepatic Foregut Cyst

• Rare (< 100 cases) cystic mass with potential for development of squamous carcinoma in cyst wall

• Appears as simple or multiloculated cyst

• Cyst contents usually mucinous (> 90%)

Mucin may cause increased signal on T1WI

Hepatic Cavernous Hemangioma

• Simulates cyst on T2WI

• Other sequences and imaging studies (US, CT, enhanced MR)

Easy distinction from cyst due to enhancement

Biloma

• Usually results from trauma, including prior surgery

• Biliary necrosis following liver transplantation often results in biloma

• History and comparison with prior imaging usually makes distinction

Hepatic Pyogenic Abscess

• Complex, septate, cystic mass

• Heterogeneous contents, > water density

• May show mural nodularity and thick enhancing wall

Hydatid (Echinococcal) Disease

• Large, well-defined, cystic liver mass with numerous peripheral “daughter” cysts

• ± calcification and dilated bile ducts

PATHOLOGY

General Features

• Etiology

Congenital simple hepatic cyst

– Defective development of intrahepatic biliary duct

• Associated abnormalities

Tuberous sclerosis

Gross Pathologic & Surgical Features

• Simple hepatic cyst

Cyst wall: ≤ 1 mm thick

Microscopic Features

• True simple hepatic cyst

Single unilocular cyst with serous fluid

Lined by cuboidal bile duct epithelium

– Thin underlying rim of fibrous stroma

No communication with bile ducts

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

Uncomplicated simple cysts are usually asymptomatic

Complicated cyst

– Pain and fever (intracystic hemorrhage or infection)

Large cysts present with symptoms of mass effect

– Abdominal pain, jaundice, palpable mass

• Other signs/symptoms

Cyst rupture with right upper quadrant (RUQ) pain

Compression of stomach or duodenum → nausea, early satiety

• Lab data is normal unless bile ducts are compressed

• Diagnosis

Fine-needle aspiration and cytology (rarely necessary)

Demographics

• Age

Seen in any age group

Many increase slowly in size

• Gender

M:F = 1:5

• Epidemiology

Prevalence: 5-15% of general population

Natural History & Prognosis

• Complications: Infection, hemorrhage, rupture (all uncommon)

• Large cyst: Symptoms due to compression

Of intrahepatic bile ducts: Jaundice

Of vessels: Varices or Budd-Chiari

Of gastric cardia: Dysphagia, abdominal pain

Treatment

• Large, symptomatic, infected hepatic cyst

Percutaneous aspiration and sclerotherapy with alcohol

Surgical resection or marsupialization (opening into peritoneal cavity)

DIAGNOSTIC CHECKLIST

Consider

• Rule out cyst-like hepatic lesions (infection, tumor)

Image Interpretation Pearls

• Sonography shows cyst morphology better than CT

May show mural nodularity, debris, septa missed by CT

• CT: Nonenhancing, well-defined, round, homogeneous water density lesion

Small lesion measuring less than blood density on NECT is probably cyst

• Hepatic metastases from GIST

Respond to chemotherapy so well that they simulate simple cysts on follow-up exams

(Left) Axial 5 mm thick CECT in a 68-year-old woman with upper abdominal discomfort shows 1 of multiple large simple cysts ; the cyst has water attenuation contents and a thin, smooth wall.

(Left) Axial 5 mm thick CECT in a 68-year-old woman with upper abdominal discomfort shows 1 of multiple large simple cysts ; the cyst has water attenuation contents and a thin, smooth wall.

(Right) Axial CT in the same case shows indistinct walls for one of the cysts , but this is due to partial volume averaging (as shown on the coronal reformatted images).

(Right) Axial CT in the same case shows indistinct walls for one of the cysts , but this is due to partial volume averaging (as shown on the coronal reformatted images).

(Left) Axial CT in the same case shows mild lobulation or septation of one of the cysts .

(Left) Axial CT in the same case shows mild lobulation or septation of one of the cysts .

(Right) Coronal CT reconstruction in the same case shows multiple large simple cysts. These have water-density contents with no enhancement, and the walls are thin and smooth. The resolution of the image in the Z axis is somewhat limited by the relatively thick (5 mm) axial sections from which this image was reconstructed. The cysts were symptomatic due to mass effect on the stomach and other structures.

(Left) CT reformation in the same case suggests that the apparent septation of 1 cyst may represent the abutting walls of 2 cysts .

(Left) CT reformation in the same case suggests that the apparent septation of 1 cyst may represent the abutting walls of 2 cysts .

(Right) Due to symptoms, the larger cysts in this same case were either opened (marsupialized) into the peritoneal cavity or resected. Note the smooth, translucent nature of the exophytic portion of the cyst wall of the excised cyst.

(Right) Due to symptoms, the larger cysts in this same case were either opened (marsupialized) into the peritoneal cavity or resected. Note the smooth, translucent nature of the exophytic portion of the cyst wall of the excised cyst.

(Left) Axial CECT shows multiple water-density hepatic lesions with no discernible walls.

(Left) Axial CECT shows multiple water-density hepatic lesions with no discernible walls.

(Right) CT section in the same case shows that 1 of the larger cysts has a thin septum . Simple hepatic cysts are commonly multiple, and this is not necessarily evidence of autosomal dominant polycystic disease, which usually results in many more and larger cysts. Biliary hamartomas can also cause an appearance of multiple cysts, but these are rarely > 15 mm.

(Right) CT section in the same case shows that 1 of the larger cysts has a thin septum . Simple hepatic cysts are commonly multiple, and this is not necessarily evidence of autosomal dominant polycystic disease, which usually results in many more and larger cysts. Biliary hamartomas can also cause an appearance of multiple cysts, but these are rarely > 15 mm.

(Left) Axial CECT of a 69-year-old woman with right upper quadrant (RUQ) pain shows a well-circumscribed cyst with a thin wall.

(Left) Axial CECT of a 69-year-old woman with right upper quadrant (RUQ) pain shows a well-circumscribed cyst with a thin wall.

(Right) CT section in this patient shows a heterogeneous focus of higher attenuation within the cyst, suggestive of acute hemorrhage.

(Right) CT section in this patient shows a heterogeneous focus of higher attenuation within the cyst, suggestive of acute hemorrhage.

(Left) CT section in the same case shows more of the intracystic hemorrhage .

(Left) CT section in the same case shows more of the intracystic hemorrhage .

(Right) CT section in this patient shows ascites that had an attenuation of about 15 HU, suggesting intraperitoneal rupture of the cyst. These findings were confirmed at surgery and the cyst was resected.

(Right) CT section in this patient shows ascites that had an attenuation of about 15 HU, suggesting intraperitoneal rupture of the cyst. These findings were confirmed at surgery and the cyst was resected.

(Left) Axial NECT in a 45-year-old man with RUQ discomfort shows several hepatic cysts, with the largest having hyperdense material settling in a dependent position.

(Left) Axial NECT in a 45-year-old man with RUQ discomfort shows several hepatic cysts, with the largest having hyperdense material settling in a dependent position.

(Right) Axial CECT in the same case shows no enhancement of the clot within the cyst. Without the NECT for comparison, it would be easy to misinterpret the clot as a mural nodularity or tumor.

(Right) Axial CECT in the same case shows no enhancement of the clot within the cyst. Without the NECT for comparison, it would be easy to misinterpret the clot as a mural nodularity or tumor.

(Left) Two masses are seen in the liver of a 70-year-old woman with RUQ pain, with the larger cyst having bright contents on T1WI, whereas the smaller cyst’s contents are low in signal.

(Left) Two masses are seen in the liver of a 70-year-old woman with RUQ pain, with the larger cyst having bright contents on T1WI, whereas the smaller cyst’s contents are low in signal.

(Right) Axial T2WI in the same case shows very bright, uniform signal within the smaller (simple) cyst , while the larger cyst’s contents are more heterogeneous with mural irregularity and debris evident . Aspiration of the larger cyst yielded hemorrhagic fluid with no sign of infection or neoplasm.

(Right) Axial T2WI in the same case shows very bright, uniform signal within the smaller (simple) cyst , while the larger cyst’s contents are more heterogeneous with mural irregularity and debris evident . Aspiration of the larger cyst yielded hemorrhagic fluid with no sign of infection or neoplasm.

(Left) Axial T1 contrast-enhanced MR shows a complex cystic mass in the right hepatic lobe. The lesion contents are hypointense, as expected for simple fluid. However, there is visible thickening of the walls of the cystic mass .

(Left) Axial T1 contrast-enhanced MR shows a complex cystic mass in the right hepatic lobe. The lesion contents are hypointense, as expected for simple fluid. However, there is visible thickening of the walls of the cystic mass .

(Right) Axial T2WI MR in the same patient shows high-intensity simple fluid within the cyst. There was no history of malignancy, and the cyst fluid was clear on aspiration. The wall thickening is presumably the result of prior infection or hemorrhage within the cyst.

(Left) Sonography in a 72-year-old man with vague upper abdominal discomfort shows a large, septate , cystic hepatic mass with accentuated through-transmission .

(Left) Sonography in a 72-year-old man with vague upper abdominal discomfort shows a large, septate , cystic hepatic mass with accentuated through-transmission .

(Right) Axial CECT in the same case shows the septate cyst , but also shows several smaller cysts .

(Right) Axial CECT in the same case shows the septate cyst , but also shows several smaller cysts .

(Left) Axial CT in this case shows the largest cyst and several smaller cysts .

(Left) Axial CT in this case shows the largest cyst and several smaller cysts .

(Right) On this axial CT in the same case, the gallbladder is seen . It was not evident whether the most caudal cystic lesion was an additional cyst or part of the largest septate cyst.

(Right) On this axial CT in the same case, the gallbladder is seen . It was not evident whether the most caudal cystic lesion was an additional cyst or part of the largest septate cyst.

(Left) Coronal CT shows the largest cyst and other smaller cysts . Note the renal cyst with a calcified wall , presumably on the basis of prior hemorrhage or infection.

(Left) Coronal CT shows the largest cyst and other smaller cysts . Note the renal cyst with a calcified wall , presumably on the basis of prior hemorrhage or infection.

(Right) CT reformation in the same case shows the largest septate cyst and numerous renal cysts. By imaging criteria alone, the large lesion identified by US and CT could not be differentiated from a biliary cystadenoma. However, cystadenomas are usually solitary and occur almost exclusively in women, whereas this patient is a man.

(Right) CT reformation in the same case shows the largest septate cyst and numerous renal cysts. By imaging criteria alone, the large lesion identified by US and CT could not be differentiated from a biliary cystadenoma. However, cystadenomas are usually solitary and occur almost exclusively in women, whereas this patient is a man.

(Left) CT shows 1 large and many smaller hepatic cysts in this 45-year-old woman with RUQ discomfort. The largest cyst is almost 15 cm in diameter and displaces hepatic vessels. Bile ducts within the left lobe are dilated due to extrinsic compression of the left main duct.

(Left) CT shows 1 large and many smaller hepatic cysts in this 45-year-old woman with RUQ discomfort. The largest cyst is almost 15 cm in diameter and displaces hepatic vessels. Bile ducts within the left lobe are dilated due to extrinsic compression of the left main duct.

(Right) CT section shows more of the obstructed bile ducts . The mass was resected and confirmed as a simple hepatic cyst.

(Right) CT section shows more of the obstructed bile ducts . The mass was resected and confirmed as a simple hepatic cyst.

(Left) Axial contrast-enhanced CT shows innumerable small cystic lesions throughout the liver, ranging in size from 2-15 mm. Close attention shows that the lesions are often not perfectly spherical and many have visible nodular enhancement within their walls.

(Left) Axial contrast-enhanced CT shows innumerable small cystic lesions throughout the liver, ranging in size from 2-15 mm. Close attention shows that the lesions are often not perfectly spherical and many have visible nodular enhancement within their walls.

(Right) US on the same patient the same day showed only the lesions > 10 mm as cystic structures whereas the smaller lesions were actually hyperechoic to background liver. This is the classic appearance of biliary hamartomas.

(Right) US on the same patient the same day showed only the lesions > 10 mm as cystic structures whereas the smaller lesions were actually hyperechoic to background liver. This is the classic appearance of biliary hamartomas.

(Left) Axial CECT shows multiple hepatic masses that have important differences in appearance. Multiple hepatic cysts are water density and homogeneous whereas multiple foci of tumor are heterogeneous and enhancing compared with NECT images.

(Left) Axial CECT shows multiple hepatic masses that have important differences in appearance. Multiple hepatic cysts are water density and homogeneous whereas multiple foci of tumor are heterogeneous and enhancing compared with NECT images.

(Right) Axial T2WI MR shows an enlarged liver with numerous large and small cysts of differing intensities in a patient with ADPLD. Cysts with high-intensity fluid also have internal septa and are the result of internal hemorrhage. Others have simple fluid .

(Right) Axial T2WI MR shows an enlarged liver with numerous large and small cysts of differing intensities in a patient with ADPLD. Cysts with high-intensity fluid also have internal septa and are the result of internal hemorrhage. Others have simple fluid .

Axial CECT shows multiple hypodense liver lesions. The largest lesion is sharply defined with a ROI of 2 HU, while the smaller lesions are too small to characterize with confidence.

Sagittal ultrasound shows an anechoic lesion with no visible wall. Note the through transmission of sound .

Sagittal ultrasound shows an anechoic lesion with no visible wall. Note the through transmission of sound .

Axial CECT shows multiple hepatic cysts of varying size with water density and no enhancement.

Sagittal sonogram shows anechoic lesions with thin walls, through transmission, and no mural nodularity.

Axial CECT shows multiple simple cysts. The smaller cysts appear of higher water density due to partial volume averaging.

Axial CECT of a patient with autosomal dominant polycystic liver disease shows innumerable hepatic cysts, though no renal cysts.

Axial T2WI MR shows a large and very hyperintense hepatic cyst with no mural nodularity or septations.

Axial CECT following blunt trauma shows peripheral water density contents that have ruptured through the capsule of the liver. Higher density hemorrhage is present in the dependent aspect of the cyst.

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