Peritoneal tumor

TUMOURS OF THE PERITONEUM

Primary tumours
Primary tumours of the peritoneum are rare and in most cases take their origin not from the serous layer but from some adjacent structure, e.g. lipoma from appendices epiploicae, fibroma from connective tissue.

Mesothelioma of the peritoneum is less frequent than in the pleural cavity but equally lethal. Asbestos is a recognised cause.
It has a predilection for the pelvic peritoneum.
Chemocytotoxic agents are the mainstay of treatment.

Desmoid tumours which have a relationship to the peritoneum are considered under familial adenomatous polyposis

Secondary tumours

Carcinomatosis peritonei

This is a common terminal event in many cases of carcinoma of the stomach, colon, ovary or other abdominal organs and also of the breast and bronchus.

The peritoneum, both parietal and visceral, is studded with secondary growths and the peritoneal cavity becomes filled with clear, straw-coloured or blood-stained ascitic fluid.


The main forms of peritoneal metastases are:
• discrete nodules – by far the most common variety;
• plaques varying in size and colour;
• diffuse adhesions – this form occurs at a late stage of the
disease and gives rise, sometimes, to a ‘frozen pelvis’.

Gravity probably determines the distribution of free malignant cells within the peritoneal cavity. Cells not caught in peritoneal folds gravitate into the pelvic pouches or into a hernial sac, the enlargement of which is occasionally the first indication of the condition.

Implantation occurs also on the greater omentum, the appendices epiploicae and the inferior surface of the diaphragm.

The main differential diagnosis is from tuberculous peritonitis (tubercles are greyish and translucent and closely resemble the discrete nodules of peritoneal carcinomatosis).

Investigation and treatment are as for underlying malignancy.

Gravity probably determines the distribution of free malignant cells within the peritoneal cavity. Cells not caught in peritoneal folds gravitate into the pelvic pouches or into a hernial sac, the enlargement of which is occasionally the first indication of the condition.

Implantation occurs also on the greater omentum, the appendices epiploicae and the inferior surface of the diaphragm.

The main differential diagnosis is from tuberculous peritonitis (tubercles are greyish and translucent and closely resemble the discrete nodules of peritoneal carcinomatosis).

Investigation and treatment are as for underlying malignancy.

At laparotomy, masses of jelly are scooped out.

The appendix, if present, should be excised together with any ovarian tumour.

Unfortunately, recurrence is inevitable, but patients may gain symptomatic benefit from repeated ‘debulking’ surgery.

Occasionally, the condition responds to radioactive isotopes or intraperitoneal chemotherapy.
The role of early radical peritoneal excision is uncertain

Pseudomyxoma Peritonei

It is a rare malignant condition that develops due to ruptured
malignant ovarian cyst or adenocarcinoma of appendix.
Peritoneum is coated with mucus secreting tumour tenacious
gel like mucus with cystic masses.
It is common in old aged females.
Vague abdominal pain with distension and dullness which
is not shifting are typical findings.
CT scan shows bowel displacement with fluid content in the peritoneal cavity.
Treatment: If origin is known then it is treated accordingly.
In patients operated by appendicectomy, removal of all mucus gel with right hemicolectomy with omentectomy is done.
If ovarian tumour is the cause then panhystrectomy with omentectomy is done.
In cases with unknown cause, after laparotomy, panhystrectomy, right hemicolectomy,omentectomy are done.


ADHESIONS
Pathophysiology
Adhesions are strands of fibrous tissue that form, usually as a result of surgery, between surgically injured tissues.

After injury, there is bleeding and an increase in vascular permeability with extravasation of fibrinogen-rich fluid from the injured surfaces forming a temporary fibrin matrix.

An inflammatory response ensues with cell migration, release of cytokines, and activation of the coagulation cascade.
The activation of the coagulation system results in thrombin formation, which is necessary for the conversion of fibrinogen to fibrin.

In the absence of fibrinolysis, adhesions will form within 5–7 days as the matrix gradually becomes more organised with collagen secretion by fibroblasts.

Fibrinolysis is therefore the key factor in determining whether

an adhesion persists.

Of great importance however to the surgeon is the fact that ischaemic tissue loses its ability to break down fibrin and inhibits fibrinolysis in adjacent tissues.

Complications

The most common adhesion-related problem is small bowel obstruction (SBO).
Adhesions are the most frequent cause of SBO in the developed world and are responsible for 60–70 per cent of SBO.

Adhesions are implicated as a major cause of secondary infertility

The relationship of adhesions to chronic abdominal and pelvic pain is contentious. Unguided division of adhesions has not been shown to reduce chronic abdominal pain in definitive randomised controlled trials although conscious pain mapping(laparoscopy under local anaesthesia) to direct lysis may improve success rates.

Prevention

Because of the scale of the problem there has been significant research into ways of preventing postoperative adhesion formation.

Minimising the production of ischaemic tissue by careful operative technique, including meticulous control of bleeding, remain however the most critical concepts.

The evolution of laparoscopic bowel surgery has been shown by collective review data to result in reduced adhesion-related readmissions for a number of abdominal and pelvic procedures, e.g. cholecystectomy, hysterectomy and colectomy.

The effect of a number of drugs including anti-inflammatory drugs like aspirin and steroids, some hormones, anticlotting agents, antibiotics, vitamin E and even methylene blue have been investigated in adhesion prevention but have not achieved
widespread use either because of side effects or lack of consistent evidence of effectiveness.

Many barrier methods of reducing adhesions have also been trialled. Adept® (4 per cent icodextrin solution) is a solution applied inside the abdomen at the time of surgery and has been shown to reduce the extent and severity of adhesion formation in animal models.

TC7® is a mesh-like product (oxidised regenerated cellulose)

which quickly forms a soft gelatinous mass around healing
tissues and is absorbed within 2 weeks. It has been shown to
significantly reduce the number of adhesions at the site where
it is used.

However, it is worth noting that a reduction in the number of adhesions in such studies does not necessarily equate to a reduction in adhesion-related problems in the future.


In a review of seven randomised trials looking at a similar barriertype product (hyaluronic acid/carboxymethyl membrane), there was a significant reduction in the incidence, extent and severity of adhesions but no reduction in the incidence of intestinal obstruction or operative intervention.

Such barriers when placed around bowel anastomosis also led to a significant increase in the anastomotic leaks. For these reasons barrier approaches have not gained popularity.

THE OMENTUM

Rutherford Morison called the greater omentum ‘ the abdominal policeman’. The greater omentum attempts, often successfully, to limit intraperitoneal infective and other noxious processes.
Torsion of the omentum
Torsion of the omentum is a rare emergency and consequently is seldom diagnosed correctly. It is usually mistaken for appendicitis with somewhat abnormal signs. It may be primary, or secondary to adhesion of the omentum to an old focus of infection or hernia.
Treatment is surgical; the pedicle above the twist is ligated securely and the mass removed.

THE MESENTERY

Mesenteric injury
A wound of the mesentery can follow severe abdominal contusion and is a cause of haemoperitoneum . More commonly, it is injured by a torsional force, so-called seatbelt syndrome. This occurs during a vehicular collision when a seatbelt is being worn with sudden deceleration resulting in a torn mesentery. This possibility should be borne in mind, particularly as multiple injuries may distract attention from this injury

Acute non-specific ileocaecal mesenteric adenitis

*Non-specific mesenteric adenitis was so named to distinguish it from specific (tuberculous) mesenteric adenitis.
It is now much more common than the tuberculous variety.
* The aetiology often remains unknown, although some cases are associated withYersinia infection of the ileum. In other cases, an unidentified virus is blamed.
*In about 25 per cent of cases, a respiratory infection precedes an attack of non-specific mesenteric adenitis. This self-limiting disease is never fatal but may be recurrent.
*Its significance thus mainly lies in its differential diagnosis with appendicitis in children.


Diagnosis
*During childhood, acute non-specific mesenteric adenitis is a
common condition.
*The typical history is one of short attacks of central abdominal pain lasting from 10 to 30 minutes , commonly associated with vomiting. The patient seldom looks ill.
* In more than half of the cases the temperature is elevated.
*Abdominal tenderness is poorly localised, and when present,
shifting tenderness is a valuable sign for differentiating the condition from appendicitis.
The neck, axillae and groins should be palpated for enlarged lymph nodes.
*There is often a leukocytosis of 10 000–12 000 μL (10–12 × 109 L) or more on the first day of the attack, but this falls on the second day.

Treatment

*When the diagnosis can be made with assurance, bed rest and
simple analgesia is the only treatment necessary.

*If at a second examination a few hours later, acute appendicitis cannot be excluded, it is safer to perform either appendicectomy or diagnostic laparoscopy.

Mesenteric cysts

Cysts may occur in the mesentery of either the small intestine
(60 per cent) or the colon (40 per cent) and can be classified as:
• chylolymphatic;
• enterogenous;
• urogenital remnant (actually retroperitoneal but project into
peritoneum);
• dermoid.


Mesenteric cysts
Cysts may occur in the mesentery of either the small intestine
(60 per cent) or the colon (40 per cent) and can be classified as:
• chylolymphatic;
• enterogenous;
• urogenital remnant (actually retroperitoneal but project into
peritoneum);
• dermoid.
Mesenteric cyst.

Chylolymphatic cyst

This is the most common variety, probably arising in congenitally
misplaced lymphatic tissue that has no efferent communication
with the lymphatic system (most frequently in the mesentery of the ileum).
Occasionally, the cyst attains a great size. More often unilocular than multilocular, a chylolymphatic cyst is almost invariably solitary, although there is an extremely rare variety in which myriads of cysts are found in the various mesenteries of the abdomen.
A chylolymphatic cyst has a blood supply that is independent from that of the adjacent intestine and, thus, enucleation is possible without the need for resection of gut.

Enterogenous cysts

These are believed to be derived either from a diverticulum of
the mesenteric border of the intestine that has become sequestrated from the intestinal canal during embryonic life or from a duplication of the intestine.


The muscle in the wall of an enteric duplication cyst and the bowel with which it is in contact have a common blood supply; consequently, removal of the cyst always entails resection of the related portion of intestine.

Urogenital remnant

A cyst developing in the retroperitoneal space often attains very large dimensions and has first to be distinguished from a large hydronephrosis.

Even after the latter condition has been eliminated by scanning or urography, a retroperitoneal cyst can seldom be distinguished with certainty from a retroperitoneal tumour until displayed at operation.

The cyst may be unilocular or multilocular. Many of these cysts are believed to be derived from a remnant of the Wolffian duct, in which case they are filled with clear fluid

Mesenteric cysts: clinical features

Cysts occur most commonly in adults with a mean age of 45 years

Twice as common in women as in men

Rare – incidence around 1 per 140 000

Approximately one-third of cases occur in children younger than 15 years
The mean age of children affected is 4.9 years

The most common presentation is of a painless abdominal swelling with characteristic physical signs there is a fluctuant swelling near the umbilicus the swelling moves freely in a plane at right angles to the attachment of the mesentery (Tillaux’s sign) there is a zone of resonance around the cyst


Other presentations are with recurrent attacks of abdominal pain with or without vomiting (pain resulting from recurring temporary impaction of a food bolus in a segment of
bowel narrowed by the cyst or possibly from torsion of the mesentery) and acute abdominal catastrophe, due to torsion of that portion of the mesentery containing the cyst

Cyst rupture, often as a result of a comparatively trivial accident

haemorrhage into the cyst
infection

Investigation and treatment

Ultrasound and CT scanning will demonstrate the lesion and
may allow diagnosis of cyst type .
There are no suitable medical therapies. The goal of surgical therapy is complete excision of the mass.
*The preferred treatment of mesenteric cysts is enucleation, although bowel resection is frequently required to ensure that the remaining bowel is viable.
*Bowel resection may be required in 50–60 per cent of children
with mesenteric cysts, whereas resection is necessary in about
one-third of adults .
* If enucleation or resection is not possible because of the size of the cyst or because of its location deep within the root of the mesentery, the third option is partial excision with marsupialisation of the remaining cyst into the abdominal cavity.

Approximately 10 per cent of patients require this form of therapy; If marsupialisation is performed, the cyst lining should be sclerosed with 10 per cent glucose solution, diathermy, or tincture of iodine to minimise recurrence.
Recurrence rates vary from 0 to 13 per cent.
Differential diagnosis
The following, although not being mesenteric cysts in the true
meaning of the term, give rise to the same physical signs:
• serosanguinous cyst, probably traumatic in origin although a
history of an accident is seldom obtained;
• tuberculous abscess of the mesentery;
• hydatid cyst of the mesentery.


Retroperitoneal (psoas) abscess
The retroperitoneal space can also be a site for abscess formation
which for practical purposes is almost synonymous with
psoas abscess.
Psoas abscess is a relatively uncommon diagnosis whose true incidence is not well described. At the beginning of the twentieth century, psoas abscess was mainly caused by tuberculosis of the spine (Pott’s disease).
With the decline of Mycobacterium tuberculosis as a major pathogen in developed countries a psoas abscess was mostly found secondary to direct spread of infection from the inflamed ± perforated digestive or urinary tract.
In recent years, a primary psoas abscess due to haematogenous spread from an occult source is more common, especially in immunocompromised and older patients as well as in association with intravenous drug misuse.

Clinical presentation is with back pain, lassitude and fever.

A swelling may point to the groin as it tracks along ileopsoas.
Pain may be elicited by passive extension of the hip or a fixed flexion of the hip evident on inspection.
Radiological investigation is via CT scanning and treatment usually by percutaneous CT-guided drainage and appropriate antibiotic therapy.

Retroperitoneal tumours

Although swellings in the retroperitoneum may include abscess,
haematoma, cysts and spread of malignancy from retroperitoneal organs (kidney, ureter, adrenal), the term retroperitoneal
tumour is usually confined to primary tumours arising in other tissues in this region, e.g. muscles, fat, lymph nodes and nerves. The management of such tumours is now frequently by referral to a specialist centre and this should be done before biopsy which may compromise subsequent surgical cure.
The two most common are Retroperitoneal lipoma and Retroperitoneal sarcoma .

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