Benignant Liver Tumours
Where is the liver located and what is its structure?
With an average weight of 1.5 kg and a capacity of three
litres, the liver is one of the biggest and most important
organs. Three quarters of it are found in the upper abdomen
on the right side, and its form resembles an oblique three-sided
pyramid. On top, it is connected to the diaphragm, and it
thus lowers when a person exhales. The doctor takes advantage
of this if he wants to palpate the lower rim of the liver
and feel its outlines. At the lower part of the liver, the
gall bladder and the lower caval vein are so deeply embedded
in its tissue that there is an asymmetrical external partition
into a small part to the left and a big one to the right.
This external view, however, contrasts strongly with the
very symmetrical inner structure of the liver, which is
subdivided into eight sections as shown by Claude Couinaud.
The internal symmetry results from a regular organisation
of one vein, one artery, and one bile duct in each of the
eight sections. These vessels receive supply from the hepatic
portal located at the bottom of the liver. It is there that
the great supplying vein and artery enter the liver. The
vein carries along oxygen-deficient blood, which is however
rich in protein, from the stomach and the bowel. It is filtered
by the liver and detoxicated in the process. The portal
vein divides into a left and a right branch right after
entering the liver. Both branches go on dividing and form
the portal vascular tree of the liver. The artery supplies
the liver tissue with blood rich in oxygen. It also branches
off various times, thus forming the arterial vascular tree
of the liver. There is a kind of an interdependent steering
mechanism between the two: in case of a very serious disease
of the liver with impairment of the blood supply in one
of the two vessels, the other vessel will compensate it.
After having passed the liver, the blood flows via the third
vascular tree, the big liver veins, into the lower caval
vein and towards the heart. At the same time, the bile produced
in the liver cells is transported from around the hepatic
porta in the opposite direction and partly stored in the
gall bladder or discharged into the duodenum for the digestion
of food. This complex inner structure still takes even highly
qualified surgeons to their limits. This is especially the
case if they try to save a small part of the liver intensively
infiltrated by a tumour, so that the patient receives the
best surgical therapy possible.
Benignant Liver Tumours
How does the liver function?
The liver, serving as a blood filter and being located between
the bowel and the rest of the organism, takes care of the
most various and complex assignments in the metabolism of
the human being. It produces important substances (blood
clotting agents and cholesterol), keeps the equilibrium
of many substances (fat, sugar, hormones, vitamins) and
helps to discharge medicaments, catabolic products, and
toxicants from the body. Besides, it is the biggest gland
and is responsible for the production and delivery of bile,
and it thus plays an important role in the digestion of
fat in the bowel. Consequently, a restriction of the function
of the liver tissue, caused by tumours or inflammations,
results in more or less grave after-effects: the glycometabolism
may be upset (hypoglycaemia), proteins are produced only
insufficiently (disorder of blood coagulation, hydro-abdomen),
and the bile salts and pigments are insufficiently discharged
(itching and yellow colouring of the skin). One of the most
important abilities of the liver is its enormous regenerative
capability. If the liver has to be partly excised and considerable
quantities of liver tissue are removed (maximum 75%), a
compensatory growth of the remaining liver will be observed
after some time. There is an increase of liver cells under
the influence of messenger substances in this process, but
there is also an obvious enlargement of the remaining liver
cells.
The most common benign liver tumours
In medicine, a fundamental difference is made between
primary and secondary tumours (metastases). Primary tumours
form in their own cells, for instance in the cells of the
liver tissue, and they can be benign or malignant. Metastases
form from scattered cells coming from distant tumour focuses
(e.g. bowel), which have wandered via the lymphatics into
the liver, and they are always malignant. During ultrasound
examinations of the liver, benign tumours are found by chance
in 9% of the population, and they are now discussed. The
names given to benign tumours of the liver depend on the
differing cells of which the liver consists and which then
multiply: for instance the liver cell itself (hepatocyte),
cells of the bile ducts (cholangio-epithelial cell) or supporting
cells (mesenchymal cell). The most common benign tumour
is the haemangioma or strawberry mark, which forms through
a proliferation of supporting cells of blood vessels. Its
size varies between some millimetres and a couple of centimetres.
Haemangiomas appear in the liver as well lined, calcified
structures and are often enclosed by a thin capsule. They
are not liable to degenerate. Also frequent and harmless
are the congenital liver cysts, which form from varying
cells and are found single or numerous in the liver tissue.
They are only removed if their size or location causes complaints.
The liver cell adenoma, a proliferation of the liver cell
itself, has to be mentioned as another benign tumour. It
is found mainly in women between 20 and 40 years old. In
the liver, single adenoma nodes are mostly found, which
however may reach a diameter of up to 30 cm and normally
are not encapsulated. In adenoma nodes, an accumulation
of fats and sugar is found. This tumour goes along with
occasional local bleedings and with necrotic liver cells
in the nodes, which may cause pains in the upper abdomen
(10% of the patients). The risk of bleedings and the risk
of degeneration ascribed to the adenoma (first stage of
a liver cell carcinoma) are the reasons, why a liver cell
adenoma is normally surgically removed. The focal nodular
hyperplasia (FNH) is the third disease to be mentioned.
It is found in men and women of every age, but more often
in women. A connection between the taking of contraceptive
hormones and the disease for women is under discussion.
Here, all original cells are found in the proliferation
of the tissue, contrary to the liver adenoma. In the case
of FNH, the liver shows nodal tumour tissue with a scar
in the centre of the tumour and star-shaped fibrous cords
progressing to the outside. To complete the picture, the
cystic tumours of the liver have to be mentioned, which
are caused by the tapeworm of the dog or the fox: cystic
and alveolar echinococcosis. These diseases are zoonoses,
i.e. diseases of the vertebrae (e.g. sheep). They can be
transmitted to human beings because, in case of an infection,
the latter serve as accidental intermediate hosts in the
stage of development of the tapeworm. If there is an infection
caused by a dog tapeworm, the liver or the lung of the human
being is affected because the ingested larva is transformed
into a hydrocyst, which is enclosed in a capsule. The larva
of the fox tapeworm, by contrast, permeates the liver with
many blisters, which have the size of a hazelnut and destroy
or displace the healthy tissue. The liquid in these blisters
contains again larvae, which is a great challenge for the
surgical and chemotherapeutical therapies as the blisters
must not burst in order to avoid an infection.
How do I recognize benign liver tumours?
The discovery of a benign liver tumour is normally a chance
diagnosis in the course of an ultrasound examination or
of other diagnostic measures because the patients are in
most cases without complaints. Most frequently, patients
with a liver cell adenoma complain of untypical pains in
the right upper abdomen as well as of bloating, slight nausea,
or fever. In comparison with other benign tumours of the
liver, one finds here sometimes slightly changed liver factors,
which may hint at a biliary stasis caused by the tumour.
Unfortunately, the often already voluminous blisters of
the dog or fox tapeworm hardly cause any complaints. In
many cases, only a blockage of the bile ducts, accompanied
by a yellow colouring of the skin, is the only hint at this
disease.
Necessary clarifications and diagnostic possibilities
Even if the majority of the benign liver tumours are discovered
through an ultrasound examination, a precise questioning
and a physical examination by the doctor will be necessary
because the sequence of the complete diagnostics must clearly
serve a characterization and confirmation of the benignancy
of the tumour. One example: the distinction between a liver
cell adenoma and a liver cell carcinoma may prove very difficult
in spite of most modern diagnostic methods. Up to 40% of
the pathological changes found by chance cannot be unequivocally
identified. It is important to find out whether the patient
has lost weight and since when he has suffered from pains
in the upper abdomen. Furthermore, it has to be clarified
whether there was a previous tumour disease and whether
hormones were taken for some years. Other questions are:
Is the patient a farmer or a forester, or is he in frequent
contact with animals for other reasons? To clarify the case
further, a blood picture, liver factors, and tumour markers
must be used to confirm the benignancy of the tumour. The
clarification whether there is a fox or dog tapeworm makes
a special examination of the blood necessary, which searches
for existing antibodies against the larva. First, ultrasound
will be used as the simplest method of diagnosis in all
cases of liver disease. Only then, a decision will be made
whether further methods like CT, MRI, or angiography will
be used for an exact diagnosis. If the diagnosis indicates
that part of the liver has to be removed, further special
examinations are carried out to test the functional soundness
of the healthy liver tissue.
How can a benign liver tumour be treated?
The methods of treatment in the case of benign liver
tumours include medicinal and surgical measures. The latter
is discussed in the chapter about "Malignant Tumours of
the Liver" because the technique for the removal of liver
tissue is almost identical.
In the case of haemangiomas of the liver, surgical indications
are given with great restraint as advantages and risks have
no sound relation to each other. So, they are simply left
in the liver tissue. They are also not punctured as the
risk of bleeding is too high, and patients are advised not
to take contraceptive hormones as they might stimulate the
growth of the haemangiomas. Only in case of very voluminous
haemangiomas or if they cause complaints, a surgical intervention
has to be considered, carefully weighing advantages and
risks. If an operation should become necessary, one would
resort to a so-called enucleation, which means that the
capsule of the haemangioma is totally extracted from the
liver tissue.
The liver cell adenoma is looked upon as being a precursor
of a liver cell carcinoma and must therefore be surgically
removed. Depending on the location of the adenoma in the
liver, central or at the rim, the surgeon chooses a method
of removal by which the tumour is totally excised, the healthy
tissue conserved, and the least surgical risk taken for
the patient. Operations, in which parts of the liver must
be removed, are subject to an increased risk of bleeding
due to the highly complicated blood supply of the liver,
thus posing a great challenge to the surgeon. Has a FNH
(focal nodular hyperplasia) been clearly diagnosed, an operation
is not indicated, but female patients are advised not to
take contraceptive hormones. This is done because scientists
surmise that its formation is triggered by hormones. But
often, the diagnosis of FNH is not safe enough, or it causes
complaints because of its size and location, so that a surgical
removal becomes inevitable. There are two principles as
to the therapy of the cysts caused by the dog or fox tapeworm:
- If at all possible a surgical treatment will be used, strictly focussing on the criteria of tumour surgery not to spread larvae cells.
- All patients have to take the vermicide mebendazol.
As to the cysts of the dog tapeworm, a surgical treatment is first choice with the objective to radically remove the parasite. The prerequisite for this is above all a favourable location of the cysts, so that the surgeon is able to excise them without danger (pericystectomy). If the cysts are diffusely spread in the liver tissue, the surgeon must carry out a removal of the liver. The more radical the operation, the less probable it is that the inflammation reoccurs. If the general state of health of a patient or an unfavourable distribution of cysts does not permit an operation, there are two methods that could be used:
- In a laparascopic operation (keyhole surgery), a special instrument is used to evacuate the cyst under strict control and dermabrade the capsule. At the same time, the above mentioned vermicide is applied in the form of pills.
- The cyst is punctured with a needle under sonographic control and the content is drained. Then a fluid to exterminate the larvae is filled into the cyst and is left there for 15 minutes when it is removed again. Also in this case the vermicide has to be taken.
For the cysts of the fox tapeworm, the same principles are valid. Only that the larvae normally spread in the liver much more aggressively. Consequently, a radical surgical solution has to be aimed at - if at all possible. Also an accompanying application of medicaments for up to 24 months or even longer becomes necessary.
What happens after the treatment?
If the ultrasound shows a small haemangioma, only systematic
ultrasound controls in the following years will be necessary
to assess its size. After the removal of an adenoma, the
patient will stay at the intensive care unit for 1 - 2 days
and then be mobilized as fast as possible. The liver regenerates
the missing parts of its tissue within 6 - 7 weeks. At the
same time, the most important liver factors are controlled
to make sure that the liver has taken up all its functions
again. With this, the patient is cured, but should receive
aftercare: ultrasound controls, if need be CT and laboratory
controls to monitor the development. In case of an FNH (focal
nodular hyperplasia), there is also the recommendation for
female patients to avoid contraceptive hormones and to undergo
a regular ultrasound control. The patients with an infection
of the fox or dog tapeworm unfortunately have to live with
the fact that they have more or less to stay under medical
treatment for the rest of their lives. This is true for
patients who underwent surgery in the same way as for those
who received a medicinal therapy. Unfortunately, there is
still no blood test or any other method to prove that the
parasites were really totally removed from the body. Side
effects of the vermicide are changes in the blood picture,
divergent liver factors, and the loss of hair. The spectre
of aftercare therefore comprises regular laboratory examinations
to control the effective level of mebendazol and, for instance,
CT and MRI.
What has to be paid attention to in future everyday life?
The patients can lead a perfectly normal life. Only some
have to undergo certain aftercare examinations.
History
Already in Greek mythology, that is to say in the story
of Prometheus, the liver plays an important role: Prometheus,
"the one who thinks ahead", tried to cheat Zeus in favour
of man, and Zeus in turn withdrew the fire from man as a
penalty. But Prometheus stole the fire again to bring it
back to earth. So Zeus had him chained to a rock, where
eagles came to tear his liver to pieces every day, which,
however, renewed itself during the night until Heracles
one day liberated him from his pains. This story hints at
one of the most important qualities of the liver: its capability
for regeneration. For centuries, it had been mainly the
military surgeons who tried to treat open injuries of the
liver. But then, it was the introduction of general anaesthesia
and antisepsis at the end of the 19th century that enabled
Karl Langenbuch to perform the first operation of the liver
in 1888. At the same time, the basic research as to the
regeneration of the liver and the arrest of bleeding (haemostasis)
in the liver was carried out. Between 1899 and 1914, it
was especially the Viennese surgeon and scientist Emerich
Ullmann, who relatively unnoticed promoted the research
of transplantation and who must therefore be called "father
of organ transplantation", if only belatedly. Yet, the foundation
for modern liver surgery was laid in the fifties by the
great Parisian school led by Jacques Hepp. In 1954, his
assistant Claude Couinaud published the standard work on
the anatomy of the liver. He was able to prove the complex
inner structure of eight sections, which are determined
by the liver veins. Also, the immunology of transplantation
had greatly progressed in the meantime. So in 1967, Tom
Starzl was able to carry out the first successful transplantation
of a liver even if the immunosuppressive therapy was still
insufficient. The scientific efforts to develop immunosuppressive
therapies went on until 1972. Then, by chance, a substance
called cyclosporine was found, drawn from a fungus that
grows in the earth. It was able to reliably suppress the
rejection of an organ, and consequently, the rate of survival
of transplanted patients rose dramatically.