1. MEDIASTINAL BRONCHOGENIC CYSTS OF ADULTS: Report of 5 cases A.Fouad, R. Saouab, D. Essaoufi, B. Radouane, S. Chaouir, T. Amil, A. Hanine, J. El Fenni Military Teaching Hospital MV Rabat - Morocco CH2

2. INTRODUCTION Bronchogenic cysts are one of the most common bronchopulmonary malformations. Bronchogenic cysts are one of the most common bronchopulmonary malformations. Modern imaging techniques such as CT and MRI are useful for precise preoperative diagnosis. Modern imaging techniques such as CT and MRI are useful for precise preoperative diagnosis. However, despite advances in diagnostic imaging, the definitive diagnosis of a mediastinal bronchogenic cyst is histological. However, despite advances in diagnostic imaging, the definitive diagnosis of a mediastinal bronchogenic cyst is histological.

3. The aim of our study is to: Recall the etiopathogenesis, epidemiological and clinical data of mediastinal bronchogenic cysts Recall the etiopathogenesis, epidemiological and clinical data of mediastinal bronchogenic cysts Illustrate the imaging appearance in different modalities of exploration Illustrate the imaging appearance in different modalities of exploration

4. MATERIALS AND METHODS Retrospective study of 5 cases of mediastinal bronchogenic cysts in adults explored in our service over a period of 9 years. Retrospective study of 5 cases of mediastinal bronchogenic cysts in adults explored in our service over a period of 9 years. Chest radiography and chest CT were performed in all cases; MRI was realised in only one case. Chest radiography and chest CT were performed in all cases; MRI was realised in only one case. Surgical resection was performed in all patients. Surgical resection was performed in all patients. Histopathological study confirmed the diagnosis Histopathological study confirmed the diagnosis

5. RESULTS We found in our series 4 women and 1 man with an average age of 50 years. We found in our series 4 women and 1 man with an average age of 50 years. No pathologic history No pathologic history The cyst was discovered incidentally in 3 cases on the chest radiography; by dyspnea in one case and a chronic cough in other case. The cyst was discovered incidentally in 3 cases on the chest radiography; by dyspnea in one case and a chronic cough in other case. The cyst was located in the middle mediastinum in 4 cases and in the anterior mediastinum in 1case. The cyst was located in the middle mediastinum in 4 cases and in the anterior mediastinum in 1case. The mean diameter of the cyst was 6.7 cm. The mean diameter of the cyst was 6.7 cm.

6. Pathological examination of the surgical specimen led to the diagnosis in all cases. Pathological examination of the surgical specimen led to the diagnosis in all cases. The postoperative course was unremarkable. The postoperative course was unremarkable. The subsequent evolution was favorable The subsequent evolution was favorable RESULTS

7. Case n° 1 Posterior anterior and lateral chest x-ray: infero-lateral opacity of the middle and inferior mediastinum Contrast material-enhanced CT scan : a well-circumscribed cyst in contact with the inferior vena cava

8. Case n° 2 Chest radiograph: homogeneous anterior right mediastinal mass Axial contrast-enhanced chest CT scan (mediastinal window settings): a well-circumscribed homogenus cyst In the right latero-tracheal lodge

9. Axial T1 and T2-weighted MR images shows that the lesion is of similar signal intensity to that of CSF, which suggests a cyst.

10. Case n° 3 Chest radiograph: homogeneous retrocardiac mass Axial contrast-enhanced chest CT scan (mediastinal window settings) : a well-circumscribed left cyst in the middle and posterior mediastinum

11. Case n° 4 Chest radiograph: homogeneous right middle mediastinal mass Axial contrast-enhanced chest CT scan (mediastinal window settings) : a well-circumscribed cyst in the middle mediastinum

12. Case n° 5 chest radiograph: homogeneous right paracardiac mass with pleural effusion Axial contrast-enhanced chest CT scan (mediastinal window settings): a well-circumscribed hyper dense cyst in the middle mediastinum extended to posterior mediastinum,with pleural effusion.

13. DISCUSSION

14. Embryological recall Bronchogenic cysts result from abnormal budding of the ventral foregut that occurs. Bronchogenic cysts result from abnormal budding of the ventral foregut that occurs between the 26th and 40th days of gestation. They are lined with pseudostratified columnar respiratory epithelium, and their walls usually contain cartilage, smooth muscle, and mucous gland tissue(1). They are lined with pseudostratified columnar respiratory epithelium, and their walls usually contain cartilage, smooth muscle, and mucous gland tissue(1). They may be filled with clear, serous fluid or thick, mucoid material. They may be filled with clear, serous fluid or thick, mucoid material.

15. They may occur in any part of the mediastinum, but most are. They may occur in any part of the mediastinum, but most are near the tracheal carina in the middle or posterior mediastinum. Mediastinal bronchogenic cysts are sometimes associated with such as sequestration and lobar emphysema(2). Mediastinal bronchogenic cysts are sometimes associated with other congenital pulmonary malformations such as sequestration and lobar emphysema(2). They may undergo an abrupt increase in size as a result of hemorrhage or infection They may undergo an abrupt increase in size as a result of hemorrhage or infection Epidemiology

16. Clinical data The majority are asymptomatic, but they may occasionally cause symptoms secondary to compression of adjacent structures. These symptoms include chest pain, cough, dyspnea, fever, and purulent sputum(3).

17. 1. Chest radiographs: It is usually adequate for detecting homogeneous opacity; It is usually adequate for detecting larger mediastinal masses as a homogeneous opacity ; But, it is limited in the tissue characterization of the lesion But, it is limited in the tissue characterization of the lesion Imaging findings

18. 2. CT scan: It is used to and clarify its It is used to characterize the mass and clarify its relationship to adjacent mediastinal structures. It is characteristic when the lesion demonstrates a with. It is characteristic when the lesion demonstrates a homogeneous fluid attenuation mass with a thin or imperceptible wall. Imaging findings

19. 2. CT scan: The attenuation value is dependent on the contents of the cyst. The attenuation value is dependent on the contents of the cyst. It can vary from to. It can vary from water attenuation to soft-tissue attenuation. The value can be owing to a high protein level or calcium oxalate in the mucoid cyst(4,5). The value can be more than 100 HU owing to a high protein level or calcium oxalate in the mucoid cyst(4,5). is uncommon and suggestive of secondary infection and communication with the tracheobronchial tree. Air within the cyst is uncommon and suggestive of secondary infection and communication with the tracheobronchial tree. Calcification occurs occasionally in the wall or within the cyst contents. Calcification occurs occasionally in the wall or within the cyst contents. Imaging findings !

20. 3. MRI: It is helpful in cases where the cystic nature of the mass is not apparent on CT. MRI should always be indicated in cases of posterior mediastinal mass to assess the relationship with the spine

21. Imaging findings 3. MRI: The cystic nature of the mass is confirmed by the high signal intensity on T2-weighted images regardless of the cyst contents. At T1-weighted images, variable patterns of signal intensity are seen because of variable cyst contents and the presence of protein, hemorrhage, or mucoid material(6). At T1-weighted images, variable patterns of signal intensity are seen because of variable cyst contents and the presence of protein, hemorrhage, or mucoid material(6). A within the bronchogenic cyst may be seen(7). A fluid-fluid level within the bronchogenic cyst may be seen(7).

22. Differential diagnosis It arises with other cystic lesions of the mediastinum including : It arises with other cystic lesions of the mediastinum including : duplication cysts, neurenteric cysts, meningocele, pericardial cysts, thymic cysts, cystic teratoma, and lymphangioma. Congenital benign cysts : duplication cysts, neurenteric cysts, meningocele, pericardial cysts, thymic cysts, cystic teratoma, and lymphangioma. Mediastinal abscess Pancreatic pseudocyst Clinical history, anatomic position, associated abnormalities and imaging semiology allow correct diagnosis in many cases.

23. The choice of treatment is controversial. The choice of treatment is controversial. Some authors advocate of all cysts given their tendency to become infected or rarely, to undergo malignant transformation(8). Some authors advocate surgical excision of all cysts given their tendency to become infected or rarely, to undergo malignant transformation(8). Increasingly, these lesions are treated with to both confirm the diagnosis and to treat them. Increasingly, these lesions are treated with transbronchial or percutaneous aspiration under CT guidance to both confirm the diagnosis and to treat them. Small lesions can be followed. Small lesions can be followed. Treatment

24. Intraoperative appearance of bronchogenic cyst Intraoperative aspiration of bronchogenic cyst.

25. CONCLUSION A with in a should be a bronchogenic cyst. A cystic mediastinal mass with a thin or imperceptible wall in a subcarinal location should be a bronchogenic cyst. In cases where the cystic nature is not apparent on CT, images should confirm the cystic nature. In cases where the cystic nature is not apparent on CT, the high signal intensity on T2-weighted images should confirm the cystic nature.

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