Completely isolated enteric duplication cyst associated with a classic enterogenous duplication cyst.

This report describes an 18-month-old boy with a completely isolated duplication cyst (CIDC) of the ileum associated with another classic enteric duplication cyst in the adjacent bowel and presenting as an acute abdomen due to torsion of the pedicle of the CIDC. Cysts excision was curative.

INTRODUCTION

Completely isolated duplication cysts (CIDC) involving the gastrointestinal tract are a rare variant of enterogenous duplication cysts.[1] Coexistence of a CIDC with a classic enterogenous duplication cyst has been reported only once earlier in the literature[2] and an acute presentation of a CIDC has not been reported earlier.

CASE REPORT

An 18-month-old boy presented with abdominal pain and distension for the past 2 days and bilious vomiting for 1 day. On examination, the child was lethargic and mildly dehydrated with a heart rate of 130/min. His abdomen was distended and tender. A vague mass was felt over the umbilical and epigastric regions. The abdominal radiographs revealed a ground-glass appearance along with a prominent bowel loop with an air-fluid level. An ultrasound (US) showed free fluid within the peritoneal cavity and an elongated, dilated, thick-walled loop of bowel in the epigastric region with inflamed mesentery. A presumptive diagnosis of small bowel volvulus with gangrene was made.

At laparotomy, approximately 200 ml of dark-red fluid was sucked out and a 25 × 9 cm tensely cystic, shiny, edematous, tubular mass with necrotic walls was found. The mass had a separate mesenteric pedicle arising from the base of the ileal mesentery, approximately 20 cm from the ileocecal junction. The pedicle had undergone torsion of three turns with resultant gangrene and perforation of the wall of the cyst. A loop of the ileum was adherent at the site of the perforation. A second cyst (8 cm in length) was present between the leaves of the ileal mesentery in the adjacent ileum, sharing a common wall with the ileum, suggesting an enteric duplication cyst. The straight arteries from the vasa recta traversed on both sides of the cyst to the adjacent bowel. The pedicle of the isolated cyst was divided between ligatures and the cyst excised. The enteric duplication cyst was excised along with the adjacent ileum and an ileoileal anastomosis performed. On sectioning the wall of the enteric duplication cyst, gastric-type mucosal folds were seen, whereas the CIDC showed a flattened inner lining. The postoperative period was uneventful. Histopathology of the CIDC revealed intestinal-type mucosa along with areas of necrosis and gangrene, while the duplication cyst adjacent to the ileum was lined entirely by gastric mucosa.

DISCUSSION

Alimentary tract duplications are usually anatomically connected with some portion of the gastrointestinal tract and have a common blood supply with the adjacent segment of intestine.[34] CIDC are a rare variant of enterogenous duplication cysts and only 12 cases have been previously reported in the English literature.[124-11] According to Menon et al.,[1] no discernible communication or connection with the adjacent alimentary tract along with the presence of the typical histopathological features of a duplication cyst would qualify for the diagnosis of a CIDC. These cysts usually present either as an incidental abdominal mass on antenatal US[4-68] or in the perinatal period.[129] Presentation as a slowly growing abdominal mass in the first[10] or third decades of life[711] has also been reported. As in our patient, the CIDC may have a stalk with a leash of vessels arising from the adjacent bowel mesentery.[167910] However, a CIDC located within the mesentery of the small bowel has been reported,[11] while in several reports,[145] the CIDC was located in the retroperitoneum.

Our patient presented with an acute abdomen due to volvulus and perforation of the cyst. An acute presentation of these cysts has not been reported earlier, although Menon et al.,[1] suggested it to be a strong possibility. Another unique feature was the coexistence of the CIDC with a classic enteric duplication cyst, a finding reported only once earlier in the literature.[2] Norris et al.,[2] described a case with a long tubular duplication of the jejunum where the proximal 10 cm segment of the cyst shared a common seromuscular coat with the bowel wall, the middle 20 cm lay separately within the leaves of the mesentery, while the final 10 cm was suspended by its own mesentery and ended blindly. Thus, the duplication became more distant from the normal bowel as one progressed distally.[2] There was another large cystic enteric duplication within the mesenteric leaves and a large left-sided posterior mediastinal cyst connected by a pedicle to a smaller cyst within the diaphragm.

Many possible embryological mechanisms have been proposed for the origin of enteric duplications, namely partial or abortive twinning,[12] split notochord theory,[13] diverticular and canalisation defects,[14] and intrauterine vascular accidents.[15] Partial or abortive twinning can explain doubling or duplication anomalies of the head, upper alimentary tract, hindgut, and the lower genitourinary tract.[312] The split notochord theory proposes that abnormal separation of the notochord from the gut endoderm can cause dorsal enteric duplications or diverticulae[13] and this can account for the 15% of enteric duplications with associated vertebral defects.[16] The theory of aberrant luminal recanalization proposes to explain duplications in those portions of the gastrointestinal tract that go through the solid stage during embryonic development such as the esophagus, small intestine, and colon.[14] As such, no single mechanism can account for all the known variants of enteric duplications. Based on their study of 83 intestinal duplications, Li et al.,[17] classified them into two types based on the vascular supply to the duplication and the adjacent bowel. In this study, 91.6% patients with type 2 cysts had associated thoracic vertebral defects and Li et al.,[17] proposed that the embryology of type 2 cysts could be explained by the split notochord theory. Type 1 cysts could be explained by the theories of midline splitting of primordial tissue and persistence of fetal gut diverticula.[17]

Menon et al.,[1] suggested that their finding of a CIDC in the mesentery of the small bowel, supplied by blood vessels from the adjacent retroperitoneum rather than the mesenteric vessels, indicated that part of the embryonic gut had been sequestered during early embryonic life. Okamoto et al.,[4] also suggested that as the blood supply to their isolated gastric duplication cyst came from the adjacent retroperitoneum, the abnormality could have occurred at a relatively early gestational age by abnormal splitting of the notochord.[4]

The CIDC in our patient as well as in other reported cases[167910] had a separate mesentery and can be considered as a variant of type 1 cysts according to Li et al.,[17] classification. The adjoining intramesenteric cyst can be classified as a type 2 cyst although the patient did not have any vertebral anomaly. However, it is difficult to explain the occurrence of two separate embryological mechanisms, as suggested by Li et al.,[17] to account for type 1 and type 2 cysts, occurring in the same patient. Steiner et al.,[6] proposed that the case reported by Norris et al.,[2] could represent an intermediate situation between a usual duplication and a completely isolated one with the proximal segment representing a classical duplication cyst and the distal segment a CIDC. This process might have been triggered by a vascular accident at the proximal end of the duplication resulting in a separated duplication cyst suspended by its own mesentery.[6] Although it is tempting to suggest that in our patient, a similar vascular accident could have resulted in complete separation of a segment from the classic duplication cyst resulting in the CIDC with its own leash of vessels, this theory cannot explain the finding that while the classic duplication cyst was lined by gastric mucosa, the adjacent CIDC was lined by intestinal mucosa. Significantly, in one of the cases reported by Norris et al.,[2] the intraabdominal duplication cysts were lined by intestinal mucosa while the mediastinal cysts were lined by gastric mucosa. Heterotopic gastric mucosa lining a CIDC has been reported,[679] while in one patient, a CIDC attached to the distal ileum was lined by respiratory epithelium.[16]

In conclusion, our case as well as the case reported by Norris et al.,[2] show that a CIDC may be associated with other enteric duplication cysts and careful examination for these must be performed during laparotomy. As suggested by Menon et al.,[1] awareness of the varied presentations of duplication cysts may help in appropriate management, without any confusion, during surgery.