Transcript E. histolytica - Stritch School of Medicine

Benign liver masses
Basic workup
• H&P, LFTS, AFP, CEA, CBC
• US, CT, or MRI
• Differentiate between primary hepatic
malignancy vs. metastatic disease vs. benign
Hepatic abscess
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Pyogenic
Amebic
Fungal
Echinococcal
Pyogenic abscess
• 80% of liver abscesses are pyogenic
• Incidence is 8-22 per 100,000
• Cholangitis is the most common cause of liver
abscesses
• Patient usually present with variable
constitutional symptoms
• US, CT, and MRI are all sensitive modalities for
identifying an abscess, however they do not
differentiate between pyogenic and amebic
Table 1 -- Pyogenic Liver Abscess Microbiology
Gram-negative
Aerobes
Escherichia coli
Common (≥10%)
Klebsiella
Gram-positive
Anaerobes
Aerobes
Staphylococcus
aureus
Bacteroides spp.
Enterococcus spp.
Viridans streptococci
Pseudomonas
Proteus
Uncommon (1%–
10%)
Enterobacter
Citrobacter
Serratia
Fusobacterium
β-hemolytic
streptococci
Anaerobic
streptococci
Clostridium
Lactobacilli
Pyogenic abscess
• Treated with antibiotics and percutaneous
drainage
• Open surgical drainage is reserved for patients
with concurrent gastrointestinal disease
processes that require surgery or those
patients who have failed percutaneous
drainage.
Pyogenic abscess
• Almost uniformly fatal if left untreated.
• Mortality rates 10-20%
• Higher success rates with antibiotics and
drainage vs. antibiotics and simple aspiration
Amebic abscess
• Amebic liver abscess is the most common
extraintestinal manifestation of the parasitic
protozoan E. histolytica
• The typical patient diagnosed with amebic liver
abscess in the United States is a young Hispanic
male between 20 and 40 years of age who has a
history of travel to an endemic area or emigration
from Mexico or Southeast Asia. Amebic liver
abscess is much more common in men, with a
male preponderance in a ratio of 10:1
Amebic abscess
• Humans are the principal host, and amebiasis
occurs after ingestion of E. histolytica cysts
through a fecal-oral route. The main source of
infection is cyst-passing chronic patients or
asymptomatic carriers who transmit the cysts
through water and vegetables contaminated
with feces, food contaminated by fertilizers or
hands of infected food handlers, or by direct
transmission
Amebic abscess
• The trophozoites aggregate in the liver
parenchyma where, through a process of
acute inflammation, granuloma formation,
and progressive tissue necrosis (hence the
name histolytica), an amebic liver abscess is
formed. The contents of the amebic abscess,
which has been classically described as
“anchovy paste,” are acellular, proteinaceous
debris and blood, surrounded by an outer rim
of Entamoebae invading healthy hepatic tissue
Amebic abscess
• Fever, hepatomegaly, and right upper
quadrant tenderness are the most frequent
findings on physical examination
• Because most patients do not have detectable
parasites in their stool, serologic testing for
antibodies to E. histolytica has become the
critical test for diagnosing amebic liver abscess
Amebic abscess
• Ultrasound, CT, and MRI are excellent at
detecting and characterizing hepatic abscesses
but are incapable of differentiating an amebic
abscess from a pyogenic liver abscess
• A 99mTc nuclear hepatic scan is able to
differentiate between a “cold” amebic liver
abscess and a “hot” pyogenic abscess because
of the presence of active leukocytes in the
pyogenic abscess
Amebic abscess
• Uncomplicated amebic liver abscess is
generally treated with amebicidal drugs alone.
Select patients may benefit from additional
therapeutic options, including simple
aspiration, percutaneous drainage, and open
surgical drainage
Amebic abscess
• Some experts suggest that simple aspiration
should be considered in patients with (1)
abscesses greater than 5 cm in size because of
the increased risk of rupture, (2) abscesses
located in the left hepatic lobe because of the
higher frequency of peritoneal leak or rupture
into the pericardium and higher mortality, (3)
failure to respond to drug therapy, and (4)
suspicion that the abscess may be pyogenic or
secondarily infected with bacteria.
Amebic abscess
• The mortality rates of patients with amebic
liver abscess are reported to be from 0% to
18%
• Higher mortality rates are seen in patients
with delayed diagnosis, secondary bacterial
infection, or complications (e.g., rupture into
peritoneal, pericardial, or pleural cavity).
• The overall incidence of rupture ranges from
3% to 17%
Amebic abscess
• Independent risk factors associated with
poorer outcomes include elevated bilirubin
(serum bilirubin level >3.5 mg/dl),
encephalopathy, hypoalbuminemia (serum
albumin level <2 g/dl), a high volume abscess
cavity (volume >500 ml), and multiple
abscesses
Fungal abscess
• Fungal liver abscesses are being recognized
with increased frequency and currently
account for approximately 10% of hepatic
abscesses
• Candida albicans and other Candida species
are found in approximately 80% of cases
• Fungal liver abscesses are usually multiple and
usually occur in immunocompromised
patients.
Fungal abscess
• Fungal liver abscesses are treated with systemic
antifungal therapy and drainage of the abscess
cavity or cavities by simple aspiration,
percutaneous drainage, or open surgical drainage
• Amphotericin B is the first-line drug of choice for
systemic antifungal therapy because of its broad
fungal efficacy
• Voriconazole or Caspofungin may be used to treat
patients who are not responding to Amphotericin
B or who have aggressive infections caused by
other fungal species
Echinococcal disease
• Echinococcus is a flat tapeworm
• Human infestation occurs with consumption
of contaminated vegetables or through
contact with infected animals or soil
• E. granulosus forms cysts that are constituted
by an external acellular layer and an inner
cellular germinal layer that produces the
brood capsules containing protoscolicies,
hydatid sand, or daughter cysts
Echinococcal disease
• The outer acellular layer is usually 2 to 5 mm
thick and is composed of fibroblasts that produce
a capsule of fibrous connective tissue called the
pericyst. The pericyst is calcified in approximately
half of patients.
• The symptoms associated with hepatic E.
granulosus can vary considerably
• specific enzyme-linked immunosorbent assay
(ELISA) and hydatid antigen immunobinding
assays yield a sensitivity and specificity up to 95%
and 90%, respectively
Echinococcal disease
Echinococcal disease
• Chemotherapy with benzimidazole compounds
(mebendazole and albendazole) is the medical
treatment of choice
• More recently, praziquantel, a synthetic
isoquinoline-pyrazine derivative, has been used in
combination with albendazole
• with medical treatment alone, only 30% of
patients can expect clinical and radiographic
resolution. Medical treatment therefore should
be used primarily in conjunction with
percutaneous drainage or surgery
Echinococcal disease
• For uncomplicated hydatid disease, morbidity
and mortality have been reported to be in the
range of 20% and 1%,
• the long-term results of PAIR and surgery for
hepatic hydatid cysts are excellent. Most
series report recurrence rates less than 10%.
Benign Hepatic Masses
• The differential diagnosis of the benign solid
hepatic mass includes hepatic adenoma, focal
nodular hyperplasia (FNH), focal fatty
infiltration, cavernous hemangioma, and other
rare neoplasms (e.g., mesenchymal
hamartoma and teratoma)
• Benign hepatic lesions are common, with an
estimated incidence of 7% to 9%, and in one
autopsy series, up to 20% of the population
Simple Cysts
• Simple cysts are solitary more than 50% of the
time and asymptomatic more than 90% of the
time.
• Size can range up to 20 cm, although most are
less than 5 cm
• Asymptomatic simple cysts less than 8 cm
require no intervention but should be
observed
Simple Cysts
Simple Cysts
• Any symptoms are usually related to mass
effect, causing pain in the right upper
quadrant and occasionally early satiety. Rarely,
intracystic hemorrhage and infection may
develop
• patients with symptomatic cysts (>5 cm)
should undergo laparoscopic or open cyst
unroofing.
Complex cysts
• If multiple simple cysts are seen, consider
polycystic liver disease
• This is an inherited condition (autosomal
dominant), often found in association with
renal cysts
• the majority of patients with polycystic liver
disease remain asymptomatic with preserved
liver function and do not require surgical
intervention
Complex cysts
Complex cysts
• Biliary cystadenomas are uncommon, slowgrowing complex cysts measuring up to 20 cm
in size. They are benign but have malignant
potential to transform into
cystadenocarcinoma and thus should be
surgically removed whenever recognized
• The diagnosis is made by the presence of
mesenchymal tissue
Complex cysts
• Radiologically, internal septations are almost
always seen in cystadenomas on contrastenhanced CT or MRI. Cystadenomas have
irregular borders and a thick stromal layer, and
calcifications and mural nodules can
occasionally be seen in the walls
Complex cysts
Hemangioma
• Autopsy series report prevalances from 0.5% to
as high as 20.0%. The female-to-male ratio is
between 5:1 and 6:1. Hemangioma is usually
found between the ages of 30 and 70 years
• tumors arise from the endothelial lining of blood
vessels as vascular ectasias and have been
associated with high estrogen states including
puberty, pregnancy, oral contraceptive use, and
androgen treatment
Hemangioma
• Most tumors are less than 5 cm and
asymptomatic
• Contrast-enhanced CT with delayed venous
examination will demonstrate peripheral
nodular enhancement and progressive
centripetal fill-in
Hemangioma
Hemangioma
• Hemangiomas almost never require surgical
resection after the diagnosis is secure because
most lesions are asymptomatic, and risk of
spontaneous rupture is extremely small.
• For symptomatic lesions, simple enucleation is
recommended because it preserves the
maximal amount of functional liver
FNH
• Focal nodular hyperplasia (FNH) is the second
most common benign solid hepatic tumor
(behind hemangioma), comprising 8% of all
primary hepatic tumors.
• Prevalence of FNH is estimated to be 3% of
the general population, predominantly in
women in their third to fifth decades.
• The female-to-male ratio is between 6:1 and
8:1
FNH
• FNH consists of benign-appearing hepatocytes
with cords of fibrous septae radiating from a
central scar, which comprises biliary structures
of hepatocellular origin
• Most patients present with an asymptomatic,
solitary tumor of less than 5 cm near the
hepatic surface. Only 10% of patients have
clinical symptoms
FNH
• On contrast-enhanced multiphasic CT imaging,
lesions are usually homogenous and
isoattenuating to liver parenchyma before
contrast injection. Lesions are bright,
hypervascular with hypodense central scarring
on arterial phase examination. If present,
radiating hypodense fibrous bands and septa
that arise from the scar are characteristic
findings
FNH
FNH
• Nuclear medicine imaging can sometimes be
helpful to distinguish FNH from hepatic
adenoma because sulfa-colloid is taken up by
Kupffer cells (present in FNH), which are
usually absent in adenoma
FNH
• Treatment strategy is heavily influenced by the
certainty of diagnosis. In asymptomatic
patients with a clear diagnosis, no further
treatment is necessary, and the patient may
be observed. In equivocal cases in which all
imaging modalities fail to establish a firm
diagnosis, biopsy is warranted for histologic
examination
Hepatic adenoma
• Hepatic adenoma (HA) is a rare hepatic tumor
that occurs predominantly in women aged 20
to 40 years, with a female-to-male ratio of at
least 4:1 and reportedly as high as 11:1.
• It has a strong association with oral
contraceptive use, with an incidence of 3 to 4
in 100,000 oral contraceptive users versus 1 in
100,000 nonusers
Hepatic adenoma
• HAs are mostly solitary (70%–80%), well
circumscribed, round, and unencapsulated. A
pseudocapsule is often present
• Larger HA tumors (>5 cm) can be associated with
right upper-quadrant pain, fullness, or
discomfort. Because of its hypervascular nature
and lack of a capsule, HA carries a moderate to
high risk of spontaneous rupture, associated with
increasing size (>5 cm). When rupture occurs, it is
intratumoral in one third of cases and
intraperitoneal in two thirds of cases.
Hepatic adenoma
• On CT, adenomas often appear heterogeneous
because of their mixed components of fat,
hemorrhage, and necrosis. On portal venous
examination or delayed images, they may
appear isodense. HAs are contrast enhancing
because of their rich vascular supply and often
show peripheral enhancement with
centripetal progression, indicating the
presence of large subcapsular feeding vessels
and early draining veins
Hepatic adenoma