Acute nonspecific ileocaecal mesenteric adenitis

Aetiology

Nonspecific mesenteric adenitis was so named to distinguish it from specific (tuberculous) mesenteric adenitis. It is now

very much more common than the tuberculous variety. Despite much investigation the aetiology often remains unknown although some cases are associated with Yersinia 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 nonspecific mesenteric adenitis. This self-limiting disease is never fatal but may be recurrent.

Pathology

There is a small increase in the amount of penitoneal fluid. The ileocaecal mesenteric lymph nodes are enlarged and can be seen and felt between the leaves of the mesentery. In very acute cases they are distinctly red and many of them are the size of a walnut. The nodes nearest the attachment of the mesentery are the largest. They are not adherent to their peritoneal coats and if a small incision is made through the overlying peritoneum, a node is extruded easily.

Clinical features

During childhood, acute nonspecific mesenteric adenitis is a common condition. It is unusual after puberty but is some­times seen in teenage girls. The typical history is one of short attacks of central abdominal pain lasting from 10 to 30 min­utes, and associated with circumoral pallor. They tend to come on when the patient is tired. Vomiting is common but there is no alteration of bowel habit. If vomiting is absent, it is more likely to be a case of mesenteric adenitis than appendicitis.

On examination

There are spasms of general abdominal colic, usually referred to the umbilicus, with intervals of complete freedom, which never appertains in obstructive appendicitis. The patient seldom looks ill. In more than half of the cases the temperature is elevated; in severe examples it exceeds 38.30C. Abdominal tenderness is greatest along the line of the mesentery. When present, shifting tenderness is a valuable sign for differentiating the condition from appendicitis. After laying the patient on the left side for a few minutes, the maximum tenderness moves to the left of the original site.

The pelvic penitoneum is tender to rectal palpation in 30 per cent of cases. The neck, axillae and groins should be palpated for enlarged lymph nodes if these nodes are enlarged, brucellosis should come to mind.

Leucocyte count

There is often a leucocytosis of 10000—12000/mm3 (10—12 x 109/litre) 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 for a few days is the only treatment necessary. If at a second examination, an hour or two after confinement to bed, acute appendicitis cannot be excluded, it is safer to perform either appendicectomy or diagnostic laparoscopy.

Tuberculosis of the mesenteric lymph nodes

Tuberculous mesenteric lymphadenitis is considerably less common than acute nonspecific lymphadenitis. Tubercle bacilli, usually, but not necessarily, bovine, are ingested and enter the mesenteric lymph nodes by way of Peyer’s patches. It is possible for one draught of raw milk to start the infection; it is equally possible that a toddler can become infected with human tubercle bacilli by placing one dust-covered small object in its mouth. Sometimes only one lymph node is infected; usually there are several; occasionally massive involvement occurs.

Presentation. Demonstrated radiologically. The shadows cast by one or more calcified tuberculous lymph nodes are seen in a plain radiograph of the abdomen. They must be distinguished from other calcified lesions, e.g. renal or ureteric stones. Their mobility on repeated plain abdominal radiographs can clinch the diagnosis but orography can be employed in doubtful cases. Often the shadow cast by such a lymph node or nodes is situated in the ileocaecal region, but nearly as many are displayed along the line of attachment of the mesentery. Usually, the radiological char­acteristics are unmistakable. Each node is round or oval, not homo­geneous, but mottled, and its outline is not regular, hut bosselated like a blackberry. Calcification of these lymph nodes occurs at the earliest in 18 months. It is often assumed, wrongly, that because a tuberculous lymph node is calcified, the infection is necessarily defunct. Especially in children, this assumption may not be valid.

As a cause of general symptoms. The patient, usually a child under 10 years of age, loses appetite, looks pale and there is some loss of weight; sometimes evening pyrexia occurs. In children with these symptoms, especially those who live in the country, if the Mantoux test is negative, brucellosis, the ‘disease of mistakes’ should be thought of and serological studies undertaken.

As a cause of abdominal pain. Sometimes abdominal pain is the cause of the patient being brought for advice; usually this pain is central, not severe but rather a discomfort and is often constant. On examination the abdomen is somewhat protuberant and there is tenderness on deep pressure to the right of the umbilicus. In these circumstances, the condition resembles acute nonspecific mesenteric lymphadenitis. On deep palpation inflamed mesenteric lymph nodes are sometimes palpable as firm, discrete, tender, bean-like objects most frequently to the right of and near the umbilicus. A normal leucocyte count favours tuberculosis and, in a child, a positive Mantoux test is confirmatory evidence of tuberculosis.

Symptoms indistinguishable from those of appendicitis. On occasions the abdominal pain is acute and may be accompanied by vomiting. This, combined with tenderness and some rigidity in the right iliac fossa, makes the diagnosis from appendicitis almost impossible. When, as is sometimes the case, the tuberculous infection of the mesenteric lymph nodes becomes reactivated in adolescent or adult life, the diagnostic difficulties are even greater. A radiograph may show calcified lymph nodes, but as such a condition can coexist with appendicitis, in some cases laparoscopy or laparotomy is necessary. If the mesentery is found to be in an inflamed state with caseation of some of the lymph nodes, the diagnosis of active tuberculosis is confirmed.

As a cause of intestinal obstruction. Remote, rather than recent, tuberculous mesenteric adenitis can be the cause of intestinal obstruction. For instance, a coil of small intestine becomes adherent to a caseating node, and is thereby angulated, or a free coil may become imprisoned in the tunnel beneath the site of adherence and the mesentery.

As a cause of pseudomesenteric cyst. When tuberculous mesenteric lymph nodes break down, the tuberculous pus may remain confined between the leaves of the mesentery, and a cystic swelling having the characteristics of a mesenteric cyst is found. When such a condition is confirmed at operation, the tuberculous pus should be aspirated without soiling the peritoneal cavity, the wound closed, the sensitivity of the organism should be sought and medical treatment continued until the infection has been overcome.

As ileocaecal lymph nodes. At laparotomy hard, enlarged lymph nodes may be found limited to the ileocaecal mesentery as a result of previous tuberculous infection. If the nodes have a yellow colour, they may well arise from a carcinoid tumour of the appendix or ileum (Chapter 57).

Treatment. Therapy is similar to that of other tuberculous infections (Chapter 8). Most cases subside but from time to time a local abscess forms, usually in the right iliac fossa when the tuberculous pus should be evacuated and the abdomen closed without drainage.

Mesenteric cysts

Mesenteric cysts are classified as:

chylolymphatic;

enterogenous;

urogenital remnant;

dermoid (teratomatous cyst).

Chylolymphatic cyst, the commonest variety of mesenteric cyst, probably arises in congenitally misplaced lymphatic tissue that has no efferent communication with the lymphatic system; it arises most frequently in the mesentery of the ileum. The thin wall of the cyst, which is composed of connective tissue lined by flat endothelium, is filled with clear lymph or, less frequently, with chyle varying in consistency from watered milk to cream. 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 independent of that of the adjacent intestine, thereby enucleation is possible without the necessity of resection of gut.

Enterogenous cyst is believed to be derived either from a diverticulum of the mesenteric border of the intestine, which has become sequestrated from the intestinal canal during embryonic life, or from a duplication of the intestine. An enterogenous cyst has a thicker wall than a chylolymphatic cyst, and it is lined by mucous membrane, sometimes ciliated. The content is mucinous, and is either colourless or yellowish-brown from bygone haemorrhage into the cyst. As can be seen at operation, the muscle in the wall of an enterogenous 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.

Clinical features of a mesenteric cyst. A mesenteric cyst is encountered most frequently in the second decade of life, less often between the ages of 1 and 10 years and, exceptionally, in infants under 1 year.

The patient presents on account of:

a painless abdominal swelling. A cyst of the mesentery presents

characteristic physical signs:

   there is a fluctuant swelling near the umbilicus (Fig. 56.15a),

   the swelling moves freely in a plane at right angles to the attachment of the mesentery (Fig. 56.15b),

   there is a zone of resonance around and, classically, a belt of resonance across the cyst;

recurrent attacks of abdominal pain with or without vomiting. The pain results from recurring temporary impaction of a food bolos in a segment of bowel narrowed by the cyst, or possibly from torsion of the mesentery;

an acute abdominal catastrophe arises as a result of:

torsion of that portion of the mesentery containing the cyst,

     rupture of the cyst, often due to a comparatively trivial accident,

     haemorrhage into the cyst,

     infection.

Radiography. In most instances, the patient should be submitted to a barium meal and follow through. The hollow viscera will be found to be displaced around the cyst and not infrequently some portion of the lumen of the small intestine will be narrowed. In order to exclude or confirm the diagnosis of a hydronephrosis, an ultrasound examination or a urogram should be performed. In cases of painless enlargement of the abdomen, an ultrasound scan should be undertaken first. Needle aspiration combined with instillation of radio opaque water-soluble contrast media can transform doubt into certainty.

Treatment. As has been indicated already, many chylolymphatic cysts can be enucleated in toto.

When, after aspiration of about half the contents of the cyst, the major portion of the cyst has been dissected free, but one portion abutting on the intestine or a major blood vessel seems too dangerous to remove, this portion can be left attached and its lining destroyed by careful diathermy.

In the case of an enterogenous cyst, enucleation must not be attempt­ed. If a comparatively short segment of the intestine is involved, resection of the cyst with the adherent portion of the intestine, followed by intestinal anastomosis, is the correct course. Should a very large segment of small intestine be implicated, an anastomosis should be made between the apex of the coil of small intestine and the cyst wall which, in this instance, holds sutures well.

The older treatment of marsupialisation of a mesenteric cyst has little to recommend it; a fistula or recurrence results. Occasionally, however, on account of its simplicity it is advisable in a poor-risk subject in whom surgery is necessary.

Omental cysts

Omental cysts occur nearly as frequently as mesenteric cysts. Preoperative differentiation is possible because a lateral radiograph, ultrasound or CT scan shows the cyst in front of the intestines. Treatment is omentectomy.

Cyst of the mesocolon

Cyst of the mesocolon is uncommon and it is differentiated from a mesenteric cyst only at operation. The treatment is similar.

Cysts arising from a urogenital remnant

Cysts arising from a urogenital (Wolffian or MUllerian) remnant are essentially retroperitoneal, hut they are included in the classification because it is not impossible for such a cyst to project forward into the mesentery.

The following, while not being mesenteric cysts in the true meaning of the term, give rise to the same physical signs and, in practice, they are mesenteric cysts:

  serosanguineous cyst is probably traumatic in origin, hut a history of an accident is seldom obtained;

tuberculous abscess of the mesentery;

hydatid cyst of the mesentery.