Eur. Radiol. 7, 382–384 (1997)  Springer-Verlag 1997

European Radiology

Case report Thoracoabdominal duplication cyst: US, CT and MR findings G. Savci1, E. Balkan2, T. Ozyaman1, H. Dogruyol2, E. Tuncel1 1 2

Department of Radiology, Uludag University Medical School, Gorukle Campus, TR-16059 Gorukle, Bursa, Turkey Department of Pediatric Surgery, Uludag University Medical School Gorukle Campus, TR-16059 Gorukle, Bursa, Turkey

Received 6 November 1995; Revision received 5 January 1996; Accepted 2 February 1996

Abstract. A rare case of thoracoabdominal duplication is reported. Radiological workup including US, CT and MR provided the correct diagnosis. The US revealed the cystic nature of the lesions, whereas CT and MR showed their relationship with the diaphragm and each other. Coronal- and sagittal-plane MR images were helpful in demonstrating the extension of the lesions. The patient was discharged after an uneventful surgery and recovery. The histological evaluation revealed the cyst lined with single-layered columnar epithelium and the cyst wall contained submucosal mucous glands with underlying smooth muscle and also some mature chondroid elements with bronchogenic origin. Radiological findings and differential diagnosis are discussed. Key words: Stomach – Duplication cyst – Congenital anomalies – Gastrointestinal tract duplication – Oesophagus

Introduction Duplication of the gastrointestinal tract (GI) is a rare congenital anomaly which can occur in any segment of the alimentary tract [1–4]. By definition, they are located in or adjacent to the wall of the GI, have smoothmuscle tissue in their walls and are lined by alimentary tract mucosa [3]. Morphologically, they may be spherical or tubular; may or may not communicate with the organ of origin to whose mesenteric fold they are closely connected [2–4]. Thoracoabdominal GI duplications are a rare, but distinct, variety of tubular duplications which arise in the abdomen, pass through the diaphragm and can produce symptoms secondary to its mass effect in the posterior mediastinum [3–6]. We report a case of a thoracoabdominal duplication cyst in a 7-month-old girl and illustrate the US, CT and MR appearances. Correspondence to: G. Savci

Case report A 7-month-old girl was sent to our department for investigation of abdominal distention and a palpable mass. A firm and nontender mass was palpated in the left epigastrium. Stool test was positive for blood. An abdominal US examination revealed two cystic lesions: one in the mediastinum 5 × 5 × 5 cm sized, left to the midline; the other 8 × 10 × 10 cm sized, in the left upper quadrant of the abdomen posterior to the stomach. They were connected to each other with a narrow lumen passing through the diaphragmatic hiatus (Fig. 1). Postcontrast CT scan of the thorax and upper abdomen was compatible with the US findings (Fig. 2). An MR examination was performed using a body coil. On coronal and sagittal spin-echo images, the anatomical relationship of the cysts with the diaphragm and each other was demonstrated (Fig. 3). The cyst content had hypointense signals on T1- and hyperintense signals on T2-weighted images showing its high water content. Surgery revealed two cysts, one located posterior to the stomach and the other left to the oesophagus in the mediastinum connected to each other with a narrow lumen compatible with radiological findings. The cysts having a common muscular wall with stomach and oesophagus were excised leaving intact muscular layer at the visceral side (Fig. 4). No luminal communication between the duplication and the stomach or the oesophagus was detected. The pathological examination of the specimen displayed a cyst wall which was lined by single-layered columnar epithelium and some mature chondroid elements were found showing that it also had bronchogenic origin. Discussion Gastrointestinal duplications can occur anywhere in the alimentary tract [1, 3, 7]. The most common site is the ileum [4]; next, in order, are the oesophagus, jejunum, colon, stomach and appendix. They are named accord-

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Fig. 1. Ultrasound appearance of the thoracoabdominal duplication cyst obtained on sagittal plane. Note the communication of both cysts passing through the diaphragm Fig. 2. Contrast-enhanced CT image demonstrates the mediastinal extension left to the midline

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ing to the portion of the GI tract which they are adjacent to, rather than by their lining mucosa [3]. The lining mucosa is not necessarily that of the adjacent segment [3]. They tend to be situated on the mesenteric aspect of the alimentary tract. Gastric duplications are being located frequently on the greater curvature (65 %), sharing a vascular system and muscular wall with the stomach, but having separate mucosal lining. It occurs twice as often in females, without any geographic or racial predominance [8]. Gastric duplications are in most cases (85 %) noncommunicating and spherical structure, or tubular structure (15 %), which communicate with the organ located adjacent to it [2–4]. Ectopic tissues can be found in the walls of these lesions at all levels of duplications [3, 4, 9]. Gastric mucosa and pancreatic tissue appear to be the only ectopic tissues which are clinically significant. Ectopic gastric mucosa is found in 43 % of the oesophageal, 24 % of small bowel and 29 % of thoracoabdominal duplications, whereas ectopic pancreatic tissue is found in 37 % of gastric duplications [3]. Thoracoabdominal duplications constitute approximately 2–4 % of all duplications [3, 5, 10]. They tend to be long, often large tubular lesions which are located in the posterior mediastinum, to the right of the midline. Closed at their cranial end, thoracoabdominal duplications pass through the diaphragmatic hiatus, where 60 % of the lesions communicate with the normal duodenum, jejunum, or ileum. The remainder end blindly in the abdomen [3, 6]. Vertebral anomalies may accompany them

Fig. 3. A T1-weighted spin-echo MR image (TR/TE = 500/15) obtained on sagittal plane reveals the anatomical relationship of the hypointense cysts with diaphragm and each other Fig. 4. The photograph of the excised specimen on surgery

[3, 6, 10]. It was interesting to note that our case revealed somewhat different features such as not having other congenital anomalies and communication with gastric nor duodenal lumen at the caudal end and being situated in the left to the midline of the thoracal part. Clinically, almost half of the duplications are found during the neonatal period, 80 % within the first year [3]. Infants and children usually present with high-level GI obstruction, whereas older age groups occasionally present later, with unusual symptoms which include anaemia, relapsing pancreatitis [11], haematemesis and melena [12], ulceration [13], torsion, perforation, infection and neoplastic transformations [2, 8]. Because our case did not contain ectopic gastric mucosa, the haematemesis was most likely secondary to pressure necrosis produced by its extrinsic mass effect on the stomach. It was interesting to note that cysts did not produce obstructive symptoms despite their huge size. Differential diagnosis should include omental cyst, mesenteric cyst, meckel diverticulum [13], haemorrhagic pseudocyst secondary to pancreatitis, choledochal cyst, abscess formation secondary to inflammation and cystic or necrotic tumours secondary to degeneration [1, 3]. Radiology plays a decisive role in the diagnosis [2]. Plain radiographs have a limited role, other than demonstrating the masses associated with thoracic vertebral anomalies [3]. Gastrointestinal series may demonstrate extrinsic pressure on the stomach or oesophagus produced by the cyst [2, 7]. The US findings in a mass with

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a thin, echogenic rim, representing the mucosa and anechoic rim thought to represent the muscular wall with an anechoic central portion, are considered as characteristic of duplication cyst [7, 10]. These findings, however, are only characteristic of noncommunicating type and tubular duplication may be poorly seen secondary to air content [10]. Because our case was a noncommunicating type, US examination was not problematic. If duplications become infected, or undergo haemorrhage, echogenic internal echoes may develop. The CT technique appears to be superior to other imaging modalities, because a clear and unequivocal anatomical resolution without overshadowing can be obtained [3, 7]. Multiplanar capability of MR helps to allow the accurate assessment of the location and intimate relationship of the cysts to each other, the diaphragm and the alimentary tract [14]. The MR technique is also beneficial in the assessment of a complication such as haemorrhage into the cavity. Radioisotope scintigraphic studies with 99 m Tc show increased uptake if the cyst contains gastric mucosa [2, 3]. In conclusion, GI haemorrhage of unclear aetiology and a cystic lesion located close to any level of GI tract, especially in childhood, should raise the suspicion of GI duplication [14]. Thoracoabdominal duplication constitutes a rare variety and tends to be symptomatic earlier. Familiarity with the radiological findings of duplications not only prevents misinterpretation, but might obviate the need for an extensive workup.

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