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
•
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,
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.