Radiological Case of the Month Patrick G.

Gallagher, MD, Donald Kirks,

A

previously healthy, 4-year-old boy was admitted to the hospital with a 2-week history of diffuse, intermitAccepted for publication May 26, 1989. From the Departments of Pediatrics (Dr Gallagher) and Radiology (Dr Kirks), Children's Hospital Medical Center, University of Cincinnati (Ohio) College of Medicine. Reprint requests to Department of Radiology, Childrens Hospital of Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027 (Dr Wood).

Figure

MD

(Contributors); Beverly P. Wood,

tent abdominal

pain. He had no vomiting, diarrhea, or fever. Four days prior to admission, ecchymosis of the right scrotum was noted. This increased in intensity the day prior to admission.

Physical examination was remarkable for a large, firm, mobile, nontender abdominal mass in the middle and right lower abdomen. There were ec-

MD (Section

Editor)

chymoses of the scrotum, and the right testicle was slightly larger than the left. Laboratory evaluation revealed a hematocrit level of 0.29. Urinalysis and coagulation studies were normal. Abdominal roentgenogram (Fig 1), abdominal ultrasound (Fig 2), and computed tomographic scan (Fig 3) of the abdomen with contrast tained.

1.

Figure 3. Figure 2.

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were

ob-

Mesenteric

Cyst With Hemorrhage

Fig 1.\p=m-\Largesoft tissue mass (arrows) noted on supine abdominal roentgenogram. Fig 2.\p=m-\Ultrasoundconfirming

an

echogenic, homogeneous, 6\m=x\8-cm2

mass

(M)

without calcifications or septations in the right middle and lower abdomen. The solid mass extends across the midline and is ventral to the aorta (A) and common iliac arteries (I).

Fig 3.—Computed tomography without (top) and with (bottom) intravenous contrast enhancement showing well-defined, homogeneous abdominal mass (M) that extends from the infrarenal area to just above the bladder and crosses the midline. The mass is adjacent to the common iliac arteries (I) and compresses the inferior vena cava.

Mesenteric cysts are an uncommon origin of abdominal mass in children. These are simple cysts with no appar¬ ent connections to normal anatomic structures. Although mesenteric cysts occur in patients of all ages, one fourth of cases occur in children under 10 years of age.1 They most commonly occur in the small bowel mesentery and contain chylous fluid. Cysts aris¬ ing in the mesocolon often contain serous fluid.2 These cysts may be multilocular and grow to huge propor¬ tions, with cases reported of cysts containing over 3 L of fluid. The cause is unknown, with proposed origin in¬

cluding obstructed, malformed, or ec¬ topie lymphatic tissue.2 Pathologic examination reveals a simple cyst with lining composed of either fibrous tissue or a single layer

of endothelial cells. Smooth-muscle cells or dystrophic calcification may be present in the cyst wall. Clinical presentation is related to cyst size, location, and related compli¬ cations.3 Although many patients with mesenteric cysts are asymptomatic, abdominal pain and distention may be found. Other symptoms include nau¬ sea,

vomiting, diarrhea, fever, dysu-

ria, urinary frequency, failure thrive, and anorexia. Children

to are

likely to have a shorter duration of symptoms than adults. Physical examination frequently demonstrates abdominal distention and a smooth, soft, nontender, mobile mass. Complications of mesenteric cysts include partial or complete bowel ob¬ struction, perforation and peritonitis, and volvulus of bowel around the cyst.3 Rare complications include cyst rup¬ ture, torsion, urinary tract obstruc¬ tion, and malignant degeneration. more

Complications leading

to

a

surgical

emergency are more common in chil¬ dren.4 Ultrasound and computed tomog¬ raphy are the most valuable modalities for imaging mesenteric cysts. Ultra¬ sound usually shows a well-defined cystic mass, often with septa and a distinct echogenic rim, with no con¬ nection to bowel or retroperitoneal structures identified.5 An echogenic appearance due to hemorrhage within the mesenteric cyst is less common. Computed tomography confirms size, position, content, and precise relation of the cyst to surrounding structures.6 Differential diagnostic considerations

include bowel duplication cyst, urachal cyst, Meckel's diverticulum, lymphoma, and rhabdomyosarcoma. Treatment is enucleation of the cyst. In cases where bowel wall or surrounding vasculature is adherent to the cyst, segmental bowel resection with wedge resection of the mesentery containing the cyst may be necessary.6 Cyst aspiration, marsupialization, and partial excision are not considered appropriate surgical treatment. Re¬ currence is extremely rare after sur¬

gical extirpation.

References 1. Vanek

mesenteric,

VW, Phillips AK. Retroperitoneal, and omental cysts. Arch Surg. 1984;

119:838-842. 2. Caropreso PR. Mesenteric cysts: a review. Arch Surg. 1974;108:242-246. 3. Mollitt DL, Ballantine TVN, Grosfeld JL. Mesenteric cysts in infancy and childhood. Surg Gynecol Obstet. 1978;147:182-184. 4. Kurtz RJ, Heimann TM, Beck AR, Holt J. Mesenteric and retroperitoneal cysts. Ann Surg.

1986;203:109-112. 5. Haller JO, Schneider M, Kassner EG, Slovis TL, Perl LJ. Sonographic evaluation of mesenteric and omental masses in children. AJR. 1978; 130:269-274. 6. Haney PJ, Whitley NO. CT of benign cystic abdominal masses in children. AJR. 1984;142: 1279-1281.

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