Abstract
Mediastinal enteric cysts are a rare occurrence among adults and are usually asymptomatic. In most cases they are an incidental finding in the right hemi-mediastinum and are associated with vertebral anomalies. We report the unusual case of a 23 year old male who had a mediastinal mass on chest X-ray as an incidental finding. Chest Computed Tomography (CT) scan revealed no vertebral anomalies and a cystic mass in the left posterior mediastinum with features similar to those of a hydatid cyst.Posterolateral thoracotomy was done and the cyst was excised. Histopathology report revealed it to be an enteric cyst

Amir Humza Sohail,, Abdul Malik

Bashir Hadi,, Yousaf

Fatimi, Saulat H.

Sagheer, Shazib

English

eCommons@AKU

eCommons@AKUDepartment of Surgery Department of SurgeryMarch 2016Enteric cyst in the left posterior mediastinummimicking a hydatid cyst on chest computedtomography scanShazib SagheerAga Khan University, shazibcheema@gmail.comAbdul Malik Amir Humza Sohail,Aga Khan UniversityYousaf Bashir Hadi,Aga Khan UniversitySaulat H. FatimiAga Khan University, saulat.fatimi@aku.eduFollow this and additional works at: http://ecommons.aku.edu/pakistan_fhs_mc_surg_surgPart of the Surgery CommonsRecommended CitationSagheer, S., Amir Humza Sohail,, A., Bashir Hadi,, Y., Fatimi, S. (2016). Enteric cyst in the left posterior mediastinum mimicking ahydatid cyst on chest computed tomography scan. JPMA: Journal of Pakistan Medical Association, 66(3), 363-365.Available at: http://ecommons.aku.edu/pakistan_fhs_mc_surg_surg/134Vol. 66, No. 3, March 2016363AbstractMediastinal enteric cysts are a rare occurrence amongadults and are usually asymptomatic. In most cases theyare an incidental finding in the right hemi-mediastinumand are associated with vertebral anomalies. We reportthe unusual case of a 23 year old male who had amediastinal mass on chest X-ray as an incidental finding.Chest Computed Tomography (CT) scan revealed novertebral anomalies and a cystic mass in the left posteriormediastinum with features similar to those of a hydatidcyst. Posterolateral thoracotomy was done and the cystwas excised. Histopathology report revealed it to be anenteric cyst.Keywords: Enteric cysts, Mediastinal mass, Thoracotomy,Bronchogenic cyst.IntroductionCongenital foregut cysts arise as a consequence ofmalformations of the primitive intestine duringembryogenesis and constitute 18% of primarymediastinal masses.1 They can be classified into one of thethree categories: bronchogenic, intramural oesophagealor enteric.Enteric cysts in the mediastinum are a rare occurrence;only 1-2% of all mediastinal cysts are enteric cysts.2Histologically, their walls have a layer of smooth muscleand are lined by mucosal epithelium. 60% of them arediagnosed in infants before the age of 1 year.3 They aremore common in children and usually present withrespiratory symptoms, such as dyspnoea, stridor andcough; in adults they are mostly asymptomatic. They areusually found in the right posterior mediastinum and areassociated with vertebral anomalies.4Herein we present the case of a 23 year old male with acyst in the left posterior mediastinum but with noidentified vertebral anomalies. Upon histopathology, thecyst was identified to be an enteric cyst.Case HistoryA 23 year old male was found to have a homogenous areaof opacification with clear margins involving the leftupper and mid lung zone, as an incidental finding onchest X-ray (Figure-1). There was no evidence of lungcollapse or pleural effusion. The patient wasasymptomatic and all systemic examinations wereunremarkable. Past medical and surgical history was non-contributory. The patient was a non-smoker, did not takealcohol and had no other addictions. There were noknown allergies.Computed Tomography (CT) scan report described alobulated well-defined multiseptate lesion, measuring18.9 ×13.3 ×8.5 cm, in the left posterior mediastinum inparavertebral location (Figure-2 and 3) The features of thelesion were highly compatible with hydatid cystSerological work-up for hydatid cyst was negative.Posterolateral thoracotomy and excision of the cyst wereperformed. Intra-operatively, the cyst was not connectedto the bronchi, vertebrae or esophagus and wasSTUDENTS CORNERCASE REPORTEnteric cyst in the left posterior mediastinummimicking a hydatid cyst on chestComputed Tomography scanShazib Sagheer,1 Abdul Malik Amir Humza Sohail,2 Yousaf Bashir Hadi,3 Saulat Fatimi41-3Medical College, Cardiothoracic Surgery, 4Department of Surgery,Cardiothroacic Sugery, Aga Khan University, Karachi.Correspondence: Shazib Sagheer. Email: shazibcheema@gmail.comFigure-1: Chest X-ray showing a homogenous area of opacification with clear marginsinvolving the left upper and mid lung zone.J Pak Med Assoc364 S. Sagheer, A. M. A. H. Sohail, Y. Bashir Hadi, et alsuccessfully removed, preserving all adjacent structures.Post-operative recovery was uneventful.Histopathology report of the excised mass described amultiloculated cyst, weighing 750 grams, filled with darkbrown, thick material. Microscopically, the cyst wall wasulcerated and lined by tall columnar epithelium showinggoblet cells. The underlying stroma showed sheets ofhaemosiderin laden macrophages and clusters of mucusglands. The glands were surrounded by mild to moderatelymphocytic infiltrate with their lumen being filled withpink amorphous material. The cyst was covered bysmooth muscle, arranged in two layers, and did notcontain any cartilage. Based on these findings the finaldiagnosis of an enteric cyst was made.One other differential diagnosis was mediastinallymphangioma. The radiological findings and thehistological report did not identify any featuressuggestive of this and thus it was ruled out.The patient was advised to undergo MRI scan of the spineto evaluate any associated vertebral anomalies. However,this could not be performed because of patient refusal.DiscussionEnteric cysts, first described by Blasius in 1711,7 can befound anywhere in the alimentary canal. About 7-20% ofenteric cysts are found in the thorax3 while only 1-2% ofall mediastinal cysts are enteric cysts.2They can present with a variety of symptoms dependingupon the location of the cyst, the involved adjacentstructures and the histological features. In children theyare symptomatic and thus are diagnosed early. About60% of enteric cysts are diagnosed in patients before theage of one year, usually due to respiratory symptoms.3 Inadults they are symptomless and usually present as anincidental finding, as in our patient.Mediastinal enteric cysts may also cause severecompressive symptoms like respiratory distress,tracheobronchial obstruction and dysphagia due tooesophageal compression. Compression of mediastinalvasculature and cardiac tamponade effect bycompression of the heart can also occur.The presence of gastric or pancreatic tissue in the cyst canresult in wall ulceration, perforation and haemorrhage,leading to haemoptysis and haematemesis.3 Rupture intothe pericardium resulting in cardiac tamponade has alsobeen reported.3 Adenocarcinoma, squamous cellcarcinoma and other malignancies can also develop inenteric cysts;1 there was no histological evidence ofmalignancy in our patient. In order to prevent the above-mentioned complications, the treatment of choice forsuch lesions is excision.6Theories regarding the origin of enteric cysts pointtowards embryonic primitive foregut developmentanomalies.3 One of the most widely accepted theoriesabout the origin of enteric cysts is split notochordsyndrome which involves the persistence of neuroentericband.6 Veenklaas, in 1952, theorized that incompleteseparation of ectoderm and notochord could eventuallyresult in spinal anomalies.6 Perhaps this is why mostenteric cysts are associated with vertebral anomalies.Also, enteric cysts usually lie in the posterior mediastinumand in most instances have no connection with theFigure-2: Transverse (Left) and coronal (Right) sections of Chest CT scan showing a large mass in the left posterior mediastinum in paravertebral location.esophagus.8Our case is unique in a number of ways. Firstly, entericcysts are usually found in the right posterior mediastinumwhile in our case it was present in the left posteriormediastinum. Secondly, no vertebral anomalies wereidentified in our patient. In Ahmed, et al's series allpatients but one had vertebral anomalies.4 In 2006, ZhangKR, et al reported vertebral anomalies in 12 out of 16patients of enteric cyst.9 A right-sided posteriormediastinal mass with a vertebral defect is diagnostic ofenteric cyst in more than 70% of cases.3 Because thestrong association of enteric cysts with vertebralanomalies provides support to the notochord theory, theabsence of any anomalies in this patient and otherpreviously reported similar cases may point towardslacunae in the split notochord theory. Thirdly, features ofthe cyst on CT scan were consistent with hydatid cyst, anddid not point towards the possibility of an enteric cyst.This raises questions about the accuracy of CT scan as adiagnostic tool for mediastinal masses. For mediastinalmasses' diagnostic purposes, it has already been pointedout that CT scan is relatively inaccurate to distinguishbetween cystic and solid masses.7ConclusionIt is important to note that although enteric cysts areusually found in the right posterior mediastinum, they canbe present in the left posterior mediastinum. Also,although most enteric cysts are associated with vertebralanomalies, the absence of any vertebral anomalies shouldnot rule out the diagnosis of enteric cyst. In cases whereon radiology a hydatid cyst is found in the posteriormediastinum, the possibility of an enteric cyst must bekept in mind as a differential diagnosis; CT scan, as seen inthis case, may not be a very accurate tool for the diagnosisof mediastinal masses.Disclosure: All the authors have declared no competinginterest.References1. Suzuki K, Koyama S, Yamada S, Kawabata Y. Adenocarcinomaarising in a mediastinal enteric cyst. Intern Med 2006; 46: 781-4.2. Davis Jr R, Oldham Jr H, SabistonJr D. Primary cysts and neoplasmsof the mediastinum: recent changes in clinical presentation,methods of diagnosis, management, and results. Ann Thorac Surg1987; 44: 229-7.3. Iglesias Sentís M, Belda Sanchís J, Gimferrer Garolera JM, CatalánBiela M, Rubio Garay M, Ramírez Ruz J. [Mediastinal enteric cyst:unusual clinical presentation and histopathology]. ArchBronconeumol 2004; 40: 185-74. Ahmed S, Jolleys A, Dark J. Thoracic enteric cysts and diverticulae.Br J Surg 1972; 59: 963-85. Le Pimpec-Barthes F, Cazes A, Bagan P, Badia A, Vlas C. [Mediastinalcysts: clinical approach and treatment]. Revue de PneumologieClinique 2010; 66: 52-2.6. Birmole B, Kulkarni B, Vaidya A, Borwankar SS. Intrathoracic entericforegut duplication cyst. J Postgrad Med 1994; 40: 228-307. Pisello F, Geraci G, Arnone E, Sciutto A, Modica G, Sciumè C. Acuteonset of esophageal duplication cyst in adult. Case Report. G Chir2009; 30: 17-20.8. Carachi R, Azmy A. Foregut duplications. Pediatric SurgeryInternational 2002; 18: 371-4.9. Zhang KR, Jia HM, Pan EY, Wang LY. Diagnosis and treatment ofmediastinal enterogenous cysts in children. Chin Med Sci J 2006;21: 201-3.Vol. 66, No. 3, March 2016Enteric cyst in the left posterior mediastinum mimicking a hydatid cyst onchest Computed Tomography scan 365

Enteric cyst in the left posterior mediastinum mimicking a hydatid cyst on chest computed tomography scan

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Enteric cyst in the left posterior mediastinum mimicking a hydatid cyst on chest computed tomography scan

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