Editing Liver cysts

== Pathophysiology ==

* Fluid-filled lesions lined by a single layer of epithelium

== Presentation ==

* Majority are incidental findings
* Workup is aimed at excluding malignancy
* LFT and WCC
* Ask about:
** Foreign travel
** Drinking unfiltered water
** Contact with livestock

== '''Benign''' ==

=== '''Simple cyst''' ===

** Present in 5-18% of people
** Pathophysiology
*** Arise congenitally from aberrant intra-hepatic bile ducts that lose connection to the biliary tree
*** A single lining layer of cuboidal or columnar epithelium secretes serous fluid into the cyst cavity
*** Don't generally communicate with biliary tree
*** Often slowly expand over time
**** Majority <3cm and asymptomatic
**** Can be as large as 20cm
*** Do not have septations
** Presentation
*** Generally incidental finding
*** Can produce a vague abdominal discomfort or fullness.
*** USS-guided aspiration can help to establish whether symptoms are related to cysts
*** Can compress normal liver, inducing regional atrophy and sometimes contralateral hypertrophy
** Differential diagnosis
*** Hydatid disease
*** Cystadenoma - suspect with thick or nodular wall
*** Metastatic neuroendocrine tumour
** Complications
*** Haemorrhage into cyst - rare - acute-onset pain
** Indications for intervention
*** Symptomatic - only consider with cysts >4cm, once differentials have been thoroughly excluded
*** Diagnostic uncertainty
** Treatment
*** Aspiration and injection sclerotherapy with ethanol  is mainstay - simple aspiration will essentially guarantee recurrence
*** Surgical - fenestration, which can be performed laparoscopically. Involves puncture then APC to lining.
** No follow-up

=== '''Ciliated foregut cyst''' ===

** Very rare
** Characteristic four-layered border with a ciliated columnar epithelial lining
** Generally subcapsular location, often in segment IV around insertion of falciform ligament
** FNA may demonstrate ciliated, pseudostratified, columnar epithelium
** Generally benign, but malignant transformation has been described, especially larger
** Resection if:
*** >4cm
*** Wall abnormalities
*** Cause pain
*** Enlarge rapidly

=== '''Polycystic liver disease''' ===

** Pathophysiology
*** Distinct entity with familial inheritance
*** A/w autosomal dominant polycystic kidney disease in 90% of cases
**** Kidney cysts 
*** Cysts are histologically similar to simple cysts
*** Usually multiple microscopic hepatic cysts along with the macroscopically visible ones
*** Hepatic parenchyma and function are usually preserved
*** Stage based on Gigot classification
**** 1: limited number (<10) of large cysts (>10cm) with large areas of normal parenchyma
**** 2: Diffuse involvement of parenchyma by medium-sized cysts with large areas of uninvolved liver tissue
**** 3: Massive and diffuse involvement of the liver by small and medium-sized cysts with very little spared parenchyma
** Presentation
*** Numerous large cysts can cause abdominal pain and distension
*** Complications
**** Infection
**** Intra-cystic bleeding
**** Rupture - extremely rare, patients can continue do play contact sports etc.
** Treatment - reserved for severe symptoms related to large cysts and severe symptoms
*** Medical
**** Avoid oestrogen replacement
*** IR
**** Cyst aspiration generally fails - but important to keep in mind in cases of infected cysts
**** Hepatic artery branch embolisation may be useful - developing area
*** Surgery
**** In patients with symptoms from a few very large cysts - consider fenestration - generally done open
**** Massive cystic disease - combined resection and fenestration might be necessary - decompress and debulk the liver
**** Complications: ascites, pleural effusion - continued secretion of fluid by cyst lining
*** Transplant
**** Definitive treatment
**** Often need additional MELD points due to preserved liver function of remnant - cases are assessed subjectively - see criteria at bottom of this page
**** Combined kidney/liver transplant may be appropriate

=== '''Amoebic abscess''' ===

** See separate section

=== '''Pyogenic liver abscess''' ===

** See separate section

=== '''Hydatid cyst''' ===

** See separate section

=== '''Traumatic cyst''' ===

** Trauma/iatrogenic
** Not true cysts - lack epithelial lining
** Symptoms can be severe - pain, peritonitis if ruptures
** Take on more of a cystic appearance over time as the clot liquefies
** Conservative management unless complications develop such as bile leak, persistent pain, bleeding, or compression.

== '''Malignant''' ==

=== '''Hepatic mucinous cystic neoplasm (previously known as biliary cystadenoma)''' ===

** Most common primary cystic tumour of the liver
** Mainly women >40yo
** Can become infected or bleed
** Pathophysiology
*** Solitary lesions ranging from 1 to 40cm
**** Usually 10-20cm
**** Tend to grow slowly
*** Slow-growing, arises from biliary epithelium
*** Can occur anywhere in parenchyma, but more commonly found centrally, whereas simply cysts are more common peripherally
*** Can be uni or multiloculated
*** Three distinct layers: inner epithelium, middle mesenchymal stroma, outer pseudocapsule
*** Can have ovarian-like stroma (only seen in women) - mostly occur 30-50yo women
*** Cytology generally non-specific
*** The contained fluid is usually mucinous
*** Can transform to cystadenocarcinoma
** Radiology
*** USS - cystic structure with varying wall thickness, nodularity, internal septations, and fluid-filled locules - 'complex cyst' but usually not that complex
*** CT: hypodense, multiloculated mass with a well-defined border. Globular external surface with multiple protruding cysts. Enhancement of cyst wall and septa.
*** MRI useful in differentiating from simple cyst
** Differential diagnosis
*** Hydatid disease
** Indications for intervention
*** All should be removed due to malignant potential (15% in some studies)
*** Suspected cystadenoma should also be formally resected
*** Aspiration - high mucin content - can be useful in guiding equivocal cases
** Treatment options
*** Partial hepatectomy
*** Enucleation

=== '''Cystadenocarcinoma''' ===

** Extremely rare malignant neoplasm
** Little evidence of natural history
** Presumably occur with malignant transformation of a hepatic cystadenoma - proliferating cytologically malignant epithelium
** Imaging
*** Shouldn't communicate with bile duct - this would raise suspicion of IPMN-B/cholangiocarcinoma
*** Malignancy suggested by large projections and markedly thickened wall
** Ca-19-9 may be mildly elevated
** Treatment
*** Don't perform aspiration if suspected - high risk of seeding
*** Complete excision
** Surgical resection with IOC to exclude biliary communication

=== '''IPMN-B''' ===

** 'Cystic intraductal papillary mucinous neoplasm of the bile duct'
** Occurs generally 50-60yo
** Pathophysiology
*** Similarities to pancreatic IPMNs and hepatic cystadenomas
*** However, communicates with the bile duct, as opposed to hepatic cystadenoma, and doesn't have ovarian-like stroma
*** 'cystic-IPMN-B'
**** Generally large cystic mass of liver
**** Arise from small peripheral bile ducts
**** Extremely high malignant potential (>60% show adenocarcinoma)
*** 'duct ectatic IPMN-B'
** Radiology
*** Multilocular masses 2-17cm with septations and calcifications
*** Often contain large mural bile duct nodules with biliary duct dilation distal to the tumour
** Indications for intervention
*** High malignant potential - all should be cut out
*** Should have formal hepatectomy as can spread along bile duct lumen
** 5-year survival 60-80%

=== '''Embryonal sarcoma''' ===

** Very rare, occurs in children 2-15yo
** Very large, poorly differentiated liver tumours

=== '''Cystic HCC''' ===

** See separate section

=== '''Cystic metastasis''' ===

** Most commonly neuroendocrine tumours, sarcoma, melanoma
** Can also be seen with bronchus/breast ca or ovarian/pancreatic adenocarcinoma
** Suspect with multiple lesions with peripheral hypervascularity




[[Category:Liver]]