CASE HISTORY A right lateral cervical mass was discovered by ultrasonography at 22 weeks gestation. The mass was liquid, situated deep and close to the carotid artery and jugular vein. It measured 1.7 by 1.2 cm (Fig. 1). Doppler ultrasonography showed no sign of blood flow in the mass that grew slowly during pregnancy. At birth, the boy was healthy, weighing 3070 g and measuring 50 cm. He showed no sign of respiratory distress; respiratory rate was 40 breaths/min and pulse rate was 140 bpm. The mass was mobile, painless at palpation and visible in the right cervical region next to the sternocleidomastoid muscle, with no visible cutaneous sinus. Ultrasonography (SonoSite™, Bothell, WA) using a broadband 5-2 MHz curved array transducer measured the mass at 3.5 × 5 cm. The child was sent home after 3 days.FIG. 1: Ultrasound image at 22 weeks of gestation showing a cervical cyst.Two weeks later, the baby seemed to have difficulty eating. There was no history of epigastric discomfort, cough or regurgitation. Physical examination showed that the cervical mass had grown, and the baby's breathing was noisy with a slight stridor. His respiratory rate was 44 breaths/min. Magnetic resonance imaging under sedation showed the size of the mass (Fig. 2) and also that it compressed the trachea and extended to the aortic arch. Early surgical intervention was deemed necessary.FIG. 2: Cervical magnetic resonance images showing an ovoid cervical lesion next to the esophagus and the neck vessels displaced laterally.What is your diagnosis? ANSWER/DISCUSSION ANSWER: A cervicotomy was performed several days later using a right transverse incision. The mass was resected in toto. Macroscopically, the mass was firm and weighed 29 g. It measured 7 cm × 3.5 cm × 3 cm (Fig. 3). A transverse section showed that it contained a clear mucoid fluid and its surface was white and slightly irregular. Microscopic examination showed that the inner wall was lined by ciliated cuboidal, cylindrical epithelium and some goblet cells. The sub-mucosa contained a small number of nerves and vessels. The outer wall consisted of a thick band of smooth muscle fibers surrounded by skeletal muscle fascicles (Fig. 4a). Immunohistochemistry technique was used with different antibodies. The results revealed that the skeletal muscle fibers were positive for Desmin (Fig. 4b) and the smooth muscular fibers positive for smooth muscle actin (Fig. 4c). The epithelium was strongly positive for various cytokeratins, especially for cytokeratin 19 and 125 (Fig. 4d). These last two are usually seen in the gastrointestinal epithelium. Neither cartilaginous nor lymphoid tissue were present. The organization of the wall with the type of epithelium, the smooth muscle and the skeletal muscle bands were compatible with an esophageal duplication.FIG. 3: Macroscopic picture of the cystic mass which weighed 29 g and measured 7 × 3.5 × 3cm.FIG. 4: Microscopic pictures. a. The inner wall of the cyst is layered with ciliated cuboidal or cylindrical epithelium with some goblet cells. Underneath, the sub-mucosa contains a few small nerves and vessels. The outer wall consists of a thick band of smooth muscle fibers resembling the muscularis propria and surrounded by skeletal muscle fibers. HE ×40. b. Immunohistochemical positive reaction for Desmin in the smooth and skeletal muscle fibers. ×40. c. Immunohistochemical positive reaction for SMA within the smooth muscle layer. ×40. d. Immunohistochemical positive reaction for Cytokeratin 125 in focal tissue and in goblet cells. ×40.The child stayed in the intensive care unit for 1 week because of severe respiratory distress after the operation. A transitory palsy of the recurrent nerve was observed. The child left the hospital 14 days after the operation, by which time he had completely recovered. One month after the operation, the baby was feeding normally and postoperative stridor had disappeared. COMMENT: We describe here a true duplication of the oesophagus. The wall of the cyst lined by an intestinal type of epithelium, encircled by bands of smooth muscle and skeletal muscle fibers are all features of the upper part of the esophagus. The absence of cartilaginous tissue or lymphoid tissue in the malformation and the type of epithelium seen did not suggest a malformation like a bronchogenic or a branchial cyst. Duplications of the alimentary tract are rare malformations. More than 80% of the cases are diagnosed before the age of 2 years (1). They can occur anywhere from the mouth to the anus (1-4). The small intestine is the most common site of duplication and the esophagus the second. The cervical portion of the esophagus is rarely concerned (5,6). These malformations can be associated with other malformations such as esophageal atresia, tracheoesophageal fistula, spinal deformities, congenital heart disease, vertebral abnormalities, malrotation of the bowel, diaphragmatic hernia and Meckel's diverticulum (6,7). Duplication can be tubular, cystic, diverticular, isolated or multiple. The classic location of bowel duplication is on the mesenteric side, sharing a common muscle wall and blood supply with the associated bowel (8,9). The embryological etiology of this malformation is not completely understood, but both esophageal duplication and bronchogenic cysts are believed to occur at the time of the division of the embryonic foregut (10). Histological similarities support their common origin, but true esophageal duplication contains all the layers of a normal esophagus (mucosa, sub-mucosa and muscularis propria) but no cartilaginous tissue. An ectopic gastric mucosa is found in approximately two thirds of the duplications, predisposing the mucosa to ulceration and perforation (9). The clinical manifestations of duplication depend on the location, the size and the presence of heterotopic gastric mucosa (4,11,12). The general symptoms of bowel duplication are nausea, vomiting, constipation, abdominal mass or abdominal heaviness. More specific clinical signs are melena, fresh bloody stools, ulceration or perforation resulting from intussusception or ectopic gastric/pancreatic tissue bleeding (1,2,4,6). When the malformation is situated in the thoracic part of the alimentary tract, symptoms can be dyspnea, regurgitation, cough, epigastric discomfort and anorexia (4,10,11,13). Duplication in this particular area is potentially dangerous because of the risk of respiratory distress (14) arising from compression or tracheomalacia. Differential diagnoses are bronchogenic cysts, branchial cysts or vascular malformations. Ultrasonography, prenatal or postnatal, is the preferred screening method for esophageal duplication (6). Computed tomography and magnetic resonance imaging are the best imaging modalities for evaluating suspected intrathoracic esophageal duplication. Early surgical intervention is required to prevent the complications of duplication (15).