Teaching Case

A 44-year-old woman presented to the emergency room with acute abdominal pain. Her vital signs were normal, and she was afebrile. The patient’s abdomen was tender and painful.

A 44-year-old woman with no medical or surgical history presented to the emergency room with acute abdominal pain. Her vital signs were normal, and she was afebrile. The patient’s abdomen was tender and painful. The white blood cell count was 12,800/L (normal range, 4.5–13.5 103/L). US reveal a sonolucent mass with good through transmission in right lower abdomen. Initially, pelvic computed tomography (CT) with only oral contrast material was performed. There was a large, well-circumscribed, low-attenuation, lobulated mass in right lower abdomen. That measured approximately 14 cm in the transverse dimension. Shortly after these studies, the patient was taken to the operating room and underwent a laparotomy. The cecum and the ascendant colon were resected. Gross pathologic examination of the resected specimen demonstrated a large cystic lesion into the cecum. Histologic evaluation demonstrated a cyst lining composed of normal colonic mucosa. The gross and histologic findings confirmed the diagnosis of an enteric duplication cyst arising from the cecum, which communicates with the lumen.

Enteric duplication cysts are an uncommon congenital abnormality. They can occur anywhere along the digestive tract. By definition, they are located in or adjacent to the wall of part of the gastrointestinal tract, have smooth muscle in their walls, and are lined by mucosa similar to that of some other portion of the alimentary tract, most often gastric mucosa. The mucosal lining is not necessarily that of the adjacent segment of the digestive tube. The most common site is the ileum, followed by the esophagus and duodenum. The colon is less frequently involved, and there is a gradient of decreasing frequency from the cecum to the rectum. Most duplication cysts manifest during the first year of life, although some occasionally manifest in older patients. Children can present with a variety of symptoms including abdominal distention, vomiting, bleeding, a palpable abdominal mass and rarely urinary frequency and hesitancy. Complications include perforation, intussusception, bowel obstruction from adjacent pressure or mass effect, volvulus, and associated malignancy Abdominal radiography may show a soft-tissue mass within the abdomen. Barium enema examination usually shows a mass extrinsic to the bowel lumen. Contrast material may gain access to a duplication that communicates with the lumen. US reveals either a sonolucent mass with good through transmission due to clear fluid content or an echogenic mass due to hemorrhage and inspissated material within the duplication. If the typical inner echogenic mucosal and outer hypoechoic muscle layers are seen, the diagnosis of duplication can be established. CT and MR imaging are alternative modalities that may be used when US findings are inconclusive. The majority of duplications appear on CT scans as smoothly rounded, fluid-filled cysts or tubular structures with thin, slightly enhancing walls located in or adjacent to the wall of part of the alimentary canal. The intracystic fluid has heterogeneous signal intensity on T1-weighted MR images and homogeneous high signal intensity on T2-weighted images. The differential diagnosis includes all cystic intraabdominal masses such as mesenteric and omental cysts, pancreatic pseudocysts, ovarian cysts, and so on.The treatment of choice for enteric duplication cysts is surgical excision.