Liver & intrahepatic bile ducts
Developmental anomalies / cysts
Foregut cyst
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Deputy Editor-in-Chief: Aaron R. Huber, D.O.
Last author update: 6 January 2025
Last staff update: 6 January 2025
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PubMed Search: Foregut cyst
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Clinical features | Diagnosis | Laboratory | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Gross images | Frozen section description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Electron microscopy description | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Gama JM, Oliveira RC. Foregut cyst. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/liverforegutcyst.html. Accessed January 18th, 2025.
Definition / general
- Most foregut cysts are 4 cm or smaller; the epithelium resembles bronchiolar epithelium, with smooth muscle bundles in the cyst wall
- Medial segment of the left hepatic lobe (segment IV) is the most common location
Essential features
- Rare; ~100 cases reported
- The only ciliated cyst of the liver
- More common in the medial segment of the left hepatic lobe
Terminology
- Ciliated hepatic foregut cyst (Hum Pathol 2000;31:241)
ICD coding
- SNOMED: M33400 - cyst, NOS
Epidemiology
- Slightly more common in women; some articles state this entity is more common in men (Diagn Pathol 2015;10:81)
- Ages between 20 weeks of gestation and 82 years (mean: 48 - 52.7 years) (Hum Pathol 2000;31:241, Am J Surg Pathol 1999;23:671, Case Rep Med 2013;2013:372017)
- ~100 cases reported in the English literature; true incidence is likely to be higher because most are asymptomatic (Ann Surg 1974;179:922)
Sites
- Usually subcapsular and localized in the left lobe of the liver (50% cases) in the medial segment (segment IV) (Hum Pathol 2000;31:241)
- Cases in the right lobe (36% of cases) and gallbladder have been described (Pathol Res Pract 2009;205:498, Arch Pathol Lab Med 1999;123:1115, Hum Pathol 2000;31:241)
Pathophysiology
- Congenital in nature
- Arises from evaginations from the embryonic foregut; a bronchial remnant from the proximal intestine becomes trapped in the liver during embryonic development (Am J Surg Pathol 1999;23:671)
Clinical features
- Nonspecific, abdominal pain (Hum Pathol 2000;31:241)
- Exceptionally, a foregut cyst can cause portal hypertension and splenomegaly by compression of the portal vein or jaundice by compression of the hepatic duct (Hum Pathol 2000;31:241, Am J Surg Pathol 1999;23:671)
Diagnosis
- Most commonly an incidental diagnosis during ultrasonography, surgical exploration or autopsy (Pathol Oncol Res 2002;8:278)
Laboratory
- CA 19-9, AFP and CEA serological markers are usually negative (Pathol Res Pract 2009;205:498)
- CEA may be positive (Case Reports Hepatol 2023;2023:6637890)
- CA 19-9 is not useful as it may be positive in benign cysts and negative in malignancy (Am J Gastroenterol 1998;93:2212)
Radiology description
- Appearance is variable
- Well defined anechoic or hypoechoic small masses (Hum Pathol 2000;31:241, Gastroenterol Rep (Oxf) 2017;5:75)
- Hypodense cysts with no enhancement after contrast injection in computed tomography (CT) (Hum Pathol 2000;31:241)
- On magnetic resonance imaging (MRI), they are T2 hyperintense and have a variable T1 appearance on weighted images, including T1 hyperintensity or hypointensity (Gastroenterol Rep (Oxf) 2017;5:75)
- Differential diagnosis radiologically might include other hepatic cysts, echinococcal cyst, pyogenic abscess, mesenchymal hamartoma (Gastroenterol Rep (Oxf) 2017;5:75)
Radiology images
Images hosted on other servers:
Malignant transformation (MRI)
T1 hyperintense layering (CT)
Incidental, well defined, subcapsular cyst (CT)
Prognostic factors
- Almost always benign; complete surgical excision is recommended because of small risk of malignancy (Pathol Res Pract 2009;205:498)
Case reports
- 51 year old man with ciliated foregut cyst with squamous cell carcinoma (Arch Pathol Lab Med 1999;123:1115)
- 60 year old woman with ciliated foregut cyst with squamous cell carcinoma (Pathol Res Pract 2009;205:498)
- 75 year old man underwent screening for lung cancer, with incidental discovery of a ciliated hepatic foregut cyst (Case Reports Hepatol 2023;2023:6637890)
- Series of ciliated hepatic foregut cyst cases, with 6 additional cases and extensive review of all reported cases in the English literature (Diagn Pathol 2015;10:81)
Treatment
- Treatment of choice is cyst aspiration, injection of sclerosing agents or surgical excision (Burt: MacSween's Pathology of the Liver, 6th Edition, 2011)
- Surgical excision is curative and generally the preferred method (Pathol Res Pract 2009;205:498)
Clinical images
Images hosted on other servers:
Intraoperative view of cyst in segment IV
Gross description
- Solitary, rarely multilocular, 1 - 9 cm (mean: 3 cm) (Hum Pathol 2000;31:241)
- Thin and whitish wall with a smooth to focally granular surface (Hum Pathol 2000;31:241)
- Content is mucoid to viscous with a yellowish color (Hum Pathol 2000;31:241)
Gross images
Contributed by Rui Caetano Oliveira, M.D., Ph.D.
Liver cyst
Frozen section description
- Not performed
Microscopic (histologic) description
- The only ciliated cyst of the liver
- 4 layers can be appreciated
- Ciliated pseudostratified columnar epithelium
- Subepithelial connective tissue
- Layer of smooth muscle
- Fibrous capsule
- Pseudostratified lining of ciliated columnar epithelium with goblet cells
- Subepithelial loose connective tissue, fibrous and paucicellular (Hum Pathol 2000;31:241)
- Smooth muscle layer composed of 1 - 3 discontinuous smooth muscle layers, surrounded by an outer fibrous capsule (Hum Pathol 2000;31:241)
- Fibrous capsule with arterioles and nerve trunks can be seen
- Cyst wall can be disrupted with inflammatory changes in the surrounding liver parenchyma (Hum Pathol 2000;31:241)
- Squamous metaplasia without evidence of dysplasia might occur (Diagn Pathol 2015;10:81)
- Gastric antral metaplasia might be present (Diagn Pathol 2015;10:81)
- Rarely, malignant transformation can occur and is associated with a bigger size (Pathol Res Pract 2009;205:498, Pathol Res Pract 2002;198:697, Am J Surg Pathol 1984;8:467)
Microscopic (histologic) images
Contributed by Rui Caetano Oliveira, M.D., Ph.D.
Epithelial lining
Cyst epithelium
Squamous metaplasia
Relation with liver
Cytology description
- Usually not performed; fine needle aspiration was diagnostic in 62% of cases (Case Reports Hepatol 2023;2023:6637890)
- May show ciliated cells, some inflammatory cells, goblet cells and mucus (Diagn Cytopathol 2006;34:846)
- In cases of malignant transformation, atypical cells may be present
Positive stains
- Epithelial layer stains positively for cytokeratins CAM 5.2, AE1 / AE3 and BerEP4 (Am J Surg Pathol 1999;23:671)
- Epithelial basement membrane and outer connective tissue layer stains for collagen IV and laminin (Am J Surg Pathol 1999;23:671)
- Muscle fibers stain for smooth muscle actin (Am J Surg Pathol 1999;23:671)
- Goblet cells stain for mucicarmine, PAS, PASD and Alcian blue (Hum Pathol 2000;31:241)
- Scattered endocrine cells in the epithelium are positive for endocrine markers chromogranin, synaptophysin and calcitonin (Hum Pathol 2000;31:241)
Negative stains
- Weakly positive for EMA and CEA (Am J Surg Pathol 1999;23:671)
Electron microscopy description
- Confirms the presence of cilia as well as goblet cells (Hum Pathol 2000;31:241)
Sample pathology report
- Liver, cyst excision:
- Ciliated hepatic foregut cyst, no evidence of malignant transformation
Differential diagnosis
- Simple cyst:
- Simple cuboidal or mesothelial lining
- Hydatid cyst:
- Fibrous capsule without epithelial lining
- Parasitic remnants (acellular lamellate layer and protoscolices)
- Hepatobiliary cystadenoma:
- Usually multilocular
- Mesenchymal (ovarian-like) stroma, cuboidal or columnar epithelium with a xanthogranulomatous response
- Intrahepatic choledochal cyst:
- Columnar epithelium, with walls composed of dense fibrous tissue and scattered smooth muscle and elastic fibers
- Variable chronic inflammatory infiltrate
- Cystic metastasis:
- Distinguishing metastasis from ciliated hepatic foregut cyst is usually straightforward
- Metastatic tumors can have different morphologies but are usually accompanied by stromal desmoplasia
- Cells have marked atypia, atypical mitoses and necrosis
- Distinguishing malignant transformation of ciliated hepatic foregut cyst from metastasis may be challenging
- According to the primary site, immunohistochemistry may help in differentiating both
- Clinical information and radiology are of utmost importance
- Distinguishing metastasis from ciliated hepatic foregut cyst is usually straightforward
- Endosalpingiosis:
- Morphology helps in the distinction; in endosalpingiosis, the lining is composed of 3 distinct cells: ciliated columnar cells, nonciliated columnar secretory mucous cells and intercalated or peg cells, while in ciliated hepatic foregut cyst, the lining is composed of only 1 type of cell (ciliated pseudostratified columnar epithelium)
Additional references
Board review style question #1
What is the only ciliated cyst of the liver?
- Ciliated hepatic foregut cyst
- Hepatobiliary cystadenoma
- Hydatid cyst
- Mesenchymal hamartoma
Board review style answer #1
A. Ciliated hepatic foregut cyst. It has a pseudostratified epithelium that is ciliated. Answer C is incorrect because hydatid cysts are typically lined by a thick, acellular layer and a thin germinal layer but do not have ciliated epithelium. Answer B is incorrect because the epithelium of hepatobiliary cystadenomas is typically cuboidal or columnar and lacks cilia. Answer D is incorrect because the cysts in mesenchymal hamartomas are lined with biliary type epithelium, which lacks cilia.
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Board review style question #2
What is the most common location of the ciliated hepatic foregut cyst?
- Lateral segment of left hepatic lobe
- Lateral segment of right hepatic lobe
- Medial segment of left hepatic lobe
- Medial segment of right hepatic lobe
Board review style answer #2
C. Medial segment of left hepatic lobe. The ciliated hepatic foregut cyst is most commonly located in the medial segment of the left hepatic lobe, accounting for 50% of cases. Answer D is incorrect because while the cyst occurs in the right lobe in ~36% of cases, the medial segment of the left lobe remains the most frequent site. Answers A and B are incorrect because ciliated hepatic foregut cyst is much less commonly located in the lateral segments of the left or right hepatic lobes compared to the medial segments.
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