Pediatric emergency medicine trisk 947
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A lower abdominal mass, particularly one on the left side, is more often related to
chronic functional constipation than to Hirschsprung disease. If a mass is found, a
careful review of bowel habits is important. If an abdominal mass is a fecaloma, a
large bolus of stool can usually be felt on rectal examination just inside the anus.
The evacuation of the impaction, and irrigation of the upper sigmoid colon,
should cause the mass to disappear. See Chapter 18 Constipation for the causes of
constipation.
Ovarian Masses
Simple ovarian cysts and solid teratomas are not uncommon and may be
asymptomatic even when large in size. Occasionally, the child presents with
urinary complaints from the pressure on the bladder or urethra. Granulosa cell
tumors of the ovary produce precocious puberty because they are hormonally
active tumors. They may be malignant. The sudden onset of severe abdominal
pain may indicate torsion of an ovarian mass, with resultant ovarian infarction.
Radiographs may show calcification in about half of patients with teratomas (
Fig. 116.22 ). Because an occasional ovarian tumor is malignant in children,
children with ovarian masses should be evaluated promptly and prepared for
surgery.
Omental Cysts
Omental cysts are rare, are usually asymptomatic, and can fill the abdomen. It is
often difficult to differentiate an omental cyst from ascites. Smaller cysts are
more mobile and can be pushed freely into all quadrants of the abdomen. If a cyst
volvulizes on its pedicle or has bleeding within it, it may cause abdominal pain or
tenderness. Elective surgical excision is indicated.
Mesenteric Cysts
Mesenteric cysts can occur anywhere in the mesentery but are most common in
the mesentery of the colon. They tend to be multilocular and are often discovered
during a routine examination or after an episode of abdominal trauma with
enlargement from bleeding. They are benign, but surgery is indicated, both to
confirm the diagnosis and to prevent complications. They can usually be removed
with sparing of the bowel, or they can be marsupialized into the general
peritoneal cavity where the fluid is absorbed.
FIGURE 116.22 Ovarian dermoids. Note calcification (arrowhead ) in superior aspect of a
large pelvic mass in a 12-year-old girl.
Malignant Intra-Abdominal Masses
About 50% of the solid malignant tumors seen in children occur within the
abdominal cavity. Most solid masses occur in the retroperitoneum. The most
common is neuroblastoma, followed by Wilms tumor and rhabdomyosarcoma.
Other unusual tumors, such as embryonal cell carcinomas (yolk sac tumor) and
lymphosarcoma, also occur in young children (see Chapter 98 Oncologic
Emergencies ). As with most malignant tumors, early diagnosis and treatment
provide the best prospects for a cure. Patients with newly diagnosed abdominal
tumors generally require admission for coordinated approach by the surgeon and
oncologists.
Neuroblastoma
Neuroblastoma most often occurs as a tumor arising from the adrenal gland, but it
can develop anywhere along the sympathetic chain or in the pelvis. It can grow
extensively, often crossing the midline of the abdomen and enveloping key
vascular and visceral structures. The best cure rates are generally in children who
are younger than 1 year of age at the time of diagnosis and in whom the tumor is
still localized to the point of origin. In such favorable cases, the tumor can be
totally excised. When widespread dissemination occurs, complete resection is
unwarranted because of the risk to other vital structures.
CT with contrast enhancement demonstrates precise anatomy, as well as renal
function and organ vascularity. The CT characteristics of neuroblastoma include
irregular shape, irregular margins, lack of well-defined capsules, and mixed lowdensity center. Neuroblastoma often displaces surrounding organs and encases
vessels. Prevertebral midline extension is common. There are calcifications in at
least 75% ( Fig. 116.23 ). Ultrasonography has limitations in accurately
determining tumor margins or local extension.
FIGURE 116.23 A: Celiac axis neuroblastoma. Computed tomographic (CT) section of the
abdomen shows a large lobulated mass with multiple flakes of calcification displacing stomach
and the liver (white arrow ). Note presence of retrocrural node (black arrows ). A, Aorta; L,
