Case 1 -
Sepsis/ICU Associated Cholestasis with Rapidly Progressive Fibrosis
Armed Forces Institute of Pathology
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The patient is a 45 year old man who was injured by an improvised explosive device (IED) in Iraq,
suffering severe blast and shrapnel wounds to both lower extremities and the right hip with open
comminuted fracture of the iliac wing. He was hypotensive on arrival at the combat support hospital in
Baghdad, where he was transfused with 33 units of blood and packed red cells and other blood products
before and during surgery to debride the wounds and evacuate a large retroperitoneal hematoma. He
developed acute renal failure, but two days later when stable he was transferred to a medical center in
Germany. He spent the next three weeks in intensive care on assisted ventilation and hemodialysis with
gradually improving cardiopulmonary and renal function. The abdominal, hip and lower extremity wounds
were left open for washout and debridement every 2 to 3 days. Complications included at least 2 episodes
of gram negative sepsis and an episode of ventilator-associated pneumonia as well as infections in the
hip and lower extremity wounds, treated with multiple antibiotics, primarily levofloxacin, meropenem and
vancomycin. Total parenteral nutrition (TPN) was administered from the eighth to the 22nd day
after injury. On the 16th day after injury an open cholecystectomy and liver biopsy were
performed because of elevated bilirubin and alkaline phosphatase, fever, leukocytosis and thickened
gallbladder (? ultrasound). The abdominal wound was gradually closed over the next 6 days, and he was
weaned from the ventilator, dialysis and TPN. The patient continued to improve and was sent to a
hospital in his home country on the 25th day after injury.
Case1 - Slide 1
Case 1 - Slide 2
The biopsy shows considerable bile stasis, most prominent in acinar zone 3 ("centrilobular"). There
is also zone 3 steatosis with some hepatocellular ballooning and occasional irregular cytoplasmic
inclusions but not true Mallory-Denk bodies. The portal areas are edematous and contain numerous
neutrophils, and there is acute cholangitis affecting many acinar bile ducts, along with a zone 1
(periportal) ductular reaction and associated acute inflammation. The Masson trichrome shows early zone
1 fibrosis accompanying the ductular proliferation and also zone 3 perisinusoidal/pericellular fibrosis
in the areas with bile stasis and steatosis. There are also several acini with confluent fibrosis of
zone 3, and a number of ductules are present in the same areas. Immunostains for alpha smooth muscle
actin (SMA) show numerous activated myofibroblasts accompanying the reactive ductules in zone 1 and also
in areas of pericellular fibrosis and confluent fibrosis in zone 3.
This case poses a number of questions:
1) Why was the patient jaundiced?
Bile flow is a complex, highly energy dependent phenomenon. Bilirubin, cholesterol and other lipids,
bile acids and other organic anions are cleared from the sinusoidal blood by membrane bound ATP dependant
transport proteins and receptors. In the hepatocytes they are conjugated or metabolized to increase
their aqueous solubility and transported into the bile by a number of canalicular transport proteins
against a concentration gradient. Water and electrolytes accompany bile salts and other solutes by
osmotic forces to produce normal bile. Hydrostatic pressure along with pericanalicular contractile
proteins help bile to flow through the small bile channels, and larger ducts have smooth muscle to
produce peristaltic movement of the luminal bile. There are many redundancies in the system so that
minor injuries can be absorbed without development of significant disease, and even some more significant
injuries can be mitigated. However, when an injury is sufficiently severe, cholestasis (failure of bile
flow) occurs, and as serum bilirubin rises, the patient becomes jaundiced.
Sepsis, and to a lesser extent bacterial infections that do not cause generalized sepsis, is one of
the more common causes of non-obstructive intrahepatic cholestasis. The pathogenesis is complex and
multifactorial, especially in a patient like the current example who has had severe trauma. Multiple
transfusions result in hemolysis and increased bilirubin production, while hypotensive episodes and
decreased hepatic perfusion cause delayed clearance of bilirubin and other substances. Poor hepatic
perfusion also contributes by retarding metabolism and decreasing the production of ATP, thus inhibiting
the energy dependent transport processes necessary for bile secretion. Endotoxin and proinflammatory
cytokines inhibit multiple steps in bile acid uptake, transport and excretion by the various transport
proteins. Drugs, especially antibiotics can cause idiosyncratic severe cholestatic reactions in
susceptible individuals, but lesser degrees of interference with transport proteins may also occur and
contribute to the cholestasis. Finally, TPN is also associated with intrahepatic cholestasis by poorly
understood mechanisms, many of which probably overlap with sepsis associated cholestasis.
The histologic differential diagnosis of the cholestatic injury in this case is between intrahepatic
cholestasis and large duct mechanical biliary obstruction, and the histologic findings do not allow the
distinction on morphologic grounds alone. Even without definitive evidence for absence of obstruction,
recognition of the likelihood of sepsis associated cholestasis could justify conservative management of
the patient. Nevertheless, once mechanical biliary obstruction is excluded, as it was in the present
case at the time of surgery, then sepsis is the likely principal cause with many contributing factors,
including hepatic ischemia, renal failure, multiple transfusions, hemolysis, TPN and other drugs.
2) Why is there a ductular reaction?
The prominent ductular reaction in this case consists of ductules with well-defined lumina. They are
located for the most part within and at the edges of fibrotic portal tracts and area accompanied by
neutrophils (so-called acute cholangiolitis). This type of ductular reaction was previously referred to
as "typical" and felt to be the result of proliferation of pre-existing bile ducts in acute biliary
obstruction, as opposed to "atypical" ductular reaction consisting of small anastomosing ductules with
poorly defined lumina that are associated with scarring in many chronic liver diseases. This terminology
(typical vs. atypical) is now discouraged, since the two types are often difficult to distinguish, and it
is now believed that expansion of the hepatic progenitor cells located in the canals of Hering along with
an unknown contribution from bone marrow derived progenitor cells may be the source of most of the
reactive ductules. Most studies that have shown this have been in chronic fibrosing liver diseases,
where the ductular reaction accompanies scarring, but hepatocellular regeneration from the progenitor
cell compartment also occurs in massive hepatic necrosis, so it seems likely that an acute biliary
obstruction would also trigger a progenitor cell expansion. In the present case, the patient did not
have a mechanical obstruction, but the sepsis-related cholestasis appears to have produced a functional
obstruction with acute cholangitis of the acinar bile ducts. The term "cholangitis lenta" historically
has been used for non-obstructive cholangitis related to generalized sepsis. In its most severe form
there is inspissated bile in dilated periportal ductules, a lesion that has been called "bile ductular
cholestasis" which when seen in a liver biopsy is virtually pathognomonic of sepsis.
In addition to the periportal ductular reaction, there are prominent duct-like structures in some
areas that have zone 3 ("centrilobular") fibrosis, presumably related to recent ischemic/hypoxic injury.
How they got to this location is unclear, but it is possible that they were derived from intra-acinar
progenitor cells of canals of Hering, which can extend into the parenchyma for about some distance from
the portal tract to central vein. Alternatively, they may be derived from circulating bone
marrow-derived progenitor cells. In either case, they probably play a role in fibrogenesis, as discussed
3) Why is there fibrosis after such a short time?
Hepatic fibrosis, defined as accumulation of excess extracellular matrix components, is considered to
be the liver's wound healing response to chronic injury. Whether fibrosis occurs, where it occurs, how
much takes place, and the rapidity of fibrosis progression are complicated, imperfectly understood
phenomena. The cells that produce collagen and other matrix components are predominantly activated
myofibroblasts that can be identified in tissue by the presence of alpha smooth muscle actin.
There are at least four possible sources of these myofibroblasts in injured liver tissue. The hepatic
stellate cells (previously called perisinusoidal lipocytes or Ito cells), which reside in the
perisinusoidal space of Disse where they store vitamin A and regulate sinusoidal blood flow, react to
tissue injury by transformation into activated myofibroblasts. Portal fibroblasts and myofibroblasts
also become activated, particularly in biliary tract disease. Biliary epithelial cells and possibly also
hepatocytes can undergo epithelial-mesenchymal transition to become activated myofibroblasts. And
finally, cells whose origin is in the bone marrow may travel through the circulation to sites of injury
and differentiate into myofibroblasts. The hepatic stellate cells have been most intensely studied,
since their lipid content allows them to be isolated and grown in tissue culture, but the relative roles
of the various populations is uncertain.
The mesenchymal cells that give rise to the myofibroblasts involved in production of fibrosis
accompany the ductular reaction that occurs in many types of liver injury. As the ductules derive from
hepatic epithelial progenitor cells, they are supported by and interact with mesenchymal cells, including
stellate cells, endothelial cells, and other stromal cells. Experimental models of fibrosis, such as the
bile duct ligated rat, suggest that in biliary disease, portal myofibroblasts accompanying the ductular
reaction are the major source of fibrosis. On the other hand, in diseases with intralobular fibrosis,
such as steatohepatitis and vascular disease, the stellate cells may be the major source. Other diseases
may have varying proportions of the two processes.
In the present case, the periportal fibrosis can be attributed to portal myofibroblast activation
accompanying the ductular reaction secondary to the cholangitis of sepsis. The diffuse zone 3 fibrosis
can be attributed to stellate cell activation and collagen production due to the acute cholestatic injury
with perhaps some contribution from the steatosis. The areas of confluent zone 3 fibrosis are most
likely due to ischemic injury with progenitor cell proliferation producing the ductules and myofibroblast
activation causing the scarring. The fact that so much fibrosis can occur in only sixteen days shows
that this is a highly dynamic process and that under the right circumstances, fibrosis can occur very
4) What are the long-term consequences of this injury?
At the time of discharge, the patient had shown remarkable improvement clinically, and it is quite
possible that the fibrosis may entirely disappear as the source of the injury is removed. Liver
extracellular matrix, like other tissues, contains a number of remodeling proteins, notably the matrix
metalloproteinases. Part of the process of scar formation involves inhibition of the matrix
metalloproteinases, while remodeling and resolution of fibrosis can take place by removal of activated
myofibroblasts by apoptosis, decreased matrix production and increased fibrolysis. Experimental models
of liver fibrosis and cirrhosis (such as rats with bile duct ligation or chronic carbon tetrachloride
intoxication) spontaneously improve and may revert to normal after the cause of injury is removed.
Improvement in fibrosis and even possible reversal of cirrhosis in humans has been observed following
successful therapy of chronic viral hepatitis, hemochromatosis, autoimmune hepatitis and chronic biliary
obstruction, so it is likely that this patient's liver fibrosis will improve, and it is possible that his
liver could be essentially normal within a few months.
1. Bile flow is a complex, energy dependant process, and many types of
liver injury interfere with bile flow, producing cholestasis.
2. Ductular reaction is a response to many types of liver injury.
3. Alpha smooth muscle actin positive myofibroblasts accompany
reactive ductules and produce hepatic fibrosis in many types of liver injury.
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