Ann Thorac Cardiovasc Surg 2016; 22: 370–374
Case Report
Online June 3, 2016 doi: 10.5761/atcs.cr.16-00086
Lipoma-Like Bronchogenic Cyst in the Right Chest Sidewall: A Case Report and Literature Review Wen-cheng Che, MD,1 Qi Zang, MD,2 Qiang Zhu, MD,2 Tian-chang Zhen, MD,2 Gong-zhang Su, MD,2 Peng Liu, MD,3 and Huai-jun Ji, MD4
Bronchogenic cyst most commonly occurs in the mediastinum, followed by the lung. We admitted a 59-year female patient with bronchogenic cyst being uniquely located on the right chest wall of the parietal pleura. Preoperative CT scan showed a local low-density lesion on the right chest wall. The lesion was removed by the thoracoscopic surgery. During the surgical resection, the lesion was observed to be located on the right chest wall. The lesion was surrounded by adipose tissue and covered with entire parietal pleura, which looks like lipoma. Pathological examination demonstrated that the lesion was bronchogenic cyst. In addition, previously reported cases of bronchogenic cyst were reviewed, and the relevant clinical knowledge was discussed. Keywords: foregut cyst, bronchogenic cyst, thoracic cavity, video-assisted thoracic surgery
Introduction Bronchogenic cyst is one of the early embryonic foregut cystic malformations and commonly occurs in the chest cavity. The disease is usually diagnosed in childhood with the lesions most frequently located in the mediastinum and pulmonary parenchyma.1) Although the occurrence of bronchogenic cyst in the parietal pleura has been reported,2,3) it is extremely rare that bronchogenic cyst occurs in the parietal pleura of the side chest wall of thoracic cavity, which looks like lipoma. A Pubmed search from December 1960 to February 2016 showed that the similar cases have not been reported. We reported this Shan Dong University School of Medicine, Jinan, Shandong, China Department of Thoracic Surgery, Qianfoshan Hospital Affiliated to Shandong University, Jinan, Shandong, China 3Taishan Medical University, Taian, Shandong, China 4Weifang Medical University, Weifang, Shandong, China 1 2
Received: March 29, 2016; Accepted: April 22, 2016 Corresponding author: Qiang Zhu, MD. Department of Thoracic Surgery, Qianfoshan Hospital Affiliated to Shandong University, 16766 Jingshi Road, Jinan 250014, Shandong, China Email: [email protected] ©2016 The Editorial Committee of Annals of Thoracic and Cardiovascular Surgery. All rights reserved.
370
case combined with literatures on the diagnosis and treatment of the disease in order to improve the clinician’s awareness of this disease.
Case Report This female patient (59 years old, Han nationality) who has retired from a company was observed to have a mass in the right side of the chest during health physical examination, and was admitted to the hospital on January 4, 2015. The patient did not have a family history of genetic diseases and other special medical conditions. Admission examination showed no positive signs. The preoperative concentration of carcinoembryonic antigen (CEA) was 1.12 ng/mL, neuron-specific enolase (NSE) concentration was 10.76 ng/mL, cytokeratin 19 fragment (CYFRA21-1) concentration was 1.10 ng/mL, squamous cell carcinoma antigen (SCC) concentration was 0.2 ng/mL, and the gastrin releasing peptide precursor (proGRP) concentration was 36.42 pg/mL. The concentration of these tumor markers were within the normal reference range. Chest CT showed low density local area in the chest at the level of sixth and seventh rib. The size of the low density area was approximately 2.8 × 2.5 × 2.3 cm, protruding into the Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Lipoma-Like Bronchogenic Cyst
Fig. 1 (A and B) CT scan showed that the sidewall of the right chest had low density mass (arrow).
discharged from the hospital after 5 days. There was no recurrence during the 1-year follow-up.
Discussion
Fig.2 The mass looks like lipoma under thoracoscopy (arrow).
pleural cavity with a CT value of about –133 Hu. There were no signs of local bone destruction and no obvious abnormalities in lung (Figs. 1A and 1B). This lesion on imaging was manifested as a low-density, smooth edge mass without infiltration into the ribs and intercostal tissue. Therefore, we initially believe that the lesion was a benign lipoma of the chest wall. The tumor mass was removed by thoracoscopy under anesthesia condition. During the surgery, the lesion was observed to be located on the lateral parietal pleura of the right chest wall. The maximum diameter of the mass was about 3.0 cm and it appears as a lipoma (Fig. 2). The parietal pleura covering the surface of the mass was smooth and complete. Pathological examination was performed for the resected tumor mass. Pathological examination showed that the lesion contained fibrous fatty wall structure. The cyst wall was covered with typical pseudostratified ciliated columnar epithelium. Thus, the disease was diagnosed as bronchogenic cyst (Figs. 3A and 3B). After the surgery, the patient was recovered and was Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Foregut cyst was derived from the residual foregut structure during embryonic development. According to the structure of the cyst wall, foregut cysts can be divided into four types: (1) bronchogenic cysts, (2) esophageal duplication cysts, (3) enteric duplication cysts and (4) mixed cysts. Bronchogenic cysts are congenital malformations of the bronchial tree. They are usually located in the proximal end of the trachea or bronchus. The cyst wall was pseudostratified ciliated columnar epithelium that may contain smooth muscle, cartilage and mucous glands. About 85% of bronchogenic cysts are located within the mediastinum,2,4) particularly in areas that are close to the right side of the trachea and carina and hilar.5) In addition, bronchogenic cysts can occur in the lungs, esophagus, stomach wall, paravertebral gutter, skin and subcutaneous area.6) The cysts can also move to atypical sites including neck, myocardium, pericardium, thymus, lung ligament, diaphragmatic and retroperitoneal region, and abdomen.2,4,7,8) Sometime, the cysts may even exhibit a dumbbell shape, with one part being located above the diaphragm and the other part being located below the diaphragm. The bronchogenic cyst in this patient did not occur in any of the typical areas as described above. Instead, it occurs in the inner wall of the chest and the right side of the pleura. Its position is unique, its appearance is atypical, and its lipoma manifestations are also rare. Clinical manifestations of bronchogenic cyst are associated with the cyst location, size and the oppression on its surrounding organs. If the cyst is small and does not oppress its surrounding organs as described in this patient, 371
Wen-Cheng C, et al.
Fig.3 T he inner wall of the cyst was covered with typical pseudostratified ciliated columnar epithelium (arrow: (A) HE staining ×40, (B) HE staining ×200). HE: hematoxylin-eosin
there may be no symptoms and can only be observed during physical examination. When the cysts are large, there may be symptoms of cough, chest tightness, chest pain, difficulty in breathing or swallowing difficulties (with cough being the most common symptoms) due to its oppression on trachea, bronchus, pulmonary or esophageal. A small number of patients have precordial murmur due to the oppression on pulmonary artery by the bulge of the cyst under the hilar pulmonary.9) Patients at younger age are more likely to have the compression symptoms because the trachea and bronchial tree are relatively soft and vulnerable to oppression. Some patients may have acute compression and fever symptoms because of the sudden increase of the cyst after bleeding or secondary infection within the cyst. A few patients have special manifestations, such as pleural effusion, even under the condition of intact cyst without infection or rupture.10) If the cyst penetrates into other adjacent organs, cavities, lung, trachea, esophagus and pleural cavity, symptoms of hemoptysis, hemorrhage or empyema can occur.11) Some patients’ blood carbohydrate antigen CA19-9 was increased, which may be due to the secretion of CA19-9 by the cyst wall epithelial cells.12) CA19-9 concentration was returned to the normal level after cyst resection. Because cases with combination of bronchogenic cyst and an elevated serum CA19-9 concentration are relatively rare, cystic lesions need differential diagnosis. However elevation of serum CA19-9 concentration is helpful for the diagnosis of bronchogenic cyst.13) Identification of the lesions and preoperative localization, and diagnosis rely mainly on imaging examinations. Chest X-ray examination is not helpful for the location of the lesion and diagnosis of the disease. X-ray diagnosis is merely speculative. For those bronchogenic cysts located 372
in the front of the bulge or behind the trachea, esophageal barium meal examination can observe local exogenous pressure trace in esophagus, but it is not easy to distinguish from esophageal cysts. CT scan is very helpful to determine the location of bronchogenic cyst and its relationship with the trachea and bronchus, as well as the compression of the cysts on the adjacent organs. CT scan is also helpful for the diagnosis of cyst bleeding and infection. Calcification may occur in approximately 10% of bronchogenic cysts. CT is very accurate for the diagnosis of cyst wall calcification. The CT value of the cysts can vary from a typical water density (0–20 Hu) to high density (80–90 Hu) according to the material composition of cyst fluid, different content of protein, calcium, and the presence of infection.14) CT scan showed low density (–133 Hu) of the cyst in this patient, which could be due to the low protein content within the cyst fluid and the presence of surface adipose tissue. It is not reliable to differentiate cysts from substantive tumor based merely on the CT value. MRI examination is helpful for the differentiation. Compared to CT, MRI is more sensitive for the diagnosis of bronchogenic cyst and more accurate for the lesion localization. MRI can more clearly show the different tissue components of the cyst. According to the literature, the preoperative CT diagnostic accuracy rate was 69.2%, while MRI diagnostic accuracy rate was 100%.15) Therefore, McAdams et al. suggested that CT is useful for initial evaluation of bronchogenic cysts, while MRI is needed for differentiation of high attenuation cysts from soft tissue masses.4) In the past, we only knew that bronchogenic cysts occur most commonly in the lungs and mediastinum, but never experienced the cases with the cyst located outside of the parietal pleura in the chest cavity. Coupled with the low density area with smooth edges Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Lipoma-Like Bronchogenic Cyst
in the CT scan, they are usually considered as benign lesions. These cases are therefore misdiagnosed as lipoma, without further MRI examination. Bronchogenic cyst present in chest sidewall also needs to be differentiated from lesions (e.g., pleura lipomas, pleural fibroma, neurogenic tumors, epithelioid hemangioendothelioma, and encapsulated fluid) that have similar imaging presentations. Bronchogenic cysts are pathologically characterized by the ciliated columnar epithelial cells covering the inner surface of the cyst. The inner cyst wall may contain cartilage and smooth muscle component. Presence of typical respiratory epithelium covering the wall is a necessary condition for pathological diagnosis. In contrast, cartilage or muscle components within the cyst are not essential for diagnosis. In the case reported here, the inner surface of cysts was covered with typical respiratory epithelium, however, cartilage or smooth muscle was not observed within the cyst wall. We speculated that this was possibly due to the deterioration of cartilage and smooth muscle during the development of cysts. This also demonstrated that not all of the bronchogenic cysts have typical pathological manifestations. Surgery is the preferred treatment for adults with symptomatic foregut cysts. In contrast, it is still controversial if surgery should be applied for those asymptomatic cysts. Some studies propose dynamic examination for those patients.16) However, multiple studies have shown that foregut cysts (including bronchogenic cyst and esophageal cyst) in old patients may become malignant.17) Furthermore, with the growth of bronchogenic cyst, most patients may have complications,11) which results in complicated disease conditions and surgical difficulties. Therefore, in principle, surgical resection should be applied as early as possible for the patients even without clinical symptoms. Because child has small chest cavity and symptoms can easily occur, surgery should be performed to avoid the interference of cyst on mediastinal organs development. Thoracoscopic resection is the preferred surgery for bronchogenic cyst, because it has the advantage of less trauma and quicker recovery.14) Thus, it is generally the accepted surgery. For the patient in this report, we used thoracoscopy-assisted surgical resection, which results in a successful recovery after the surgery. The patient was discharged from the hospital after only 5 hospitalized days. However, thoracoscopy-assisted surgical resection is not appropriate for patients with preoperative complications, severe adhesion between the lesions and important structures, and injuries during operation.18) If the cysts are Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
large and affect resection, puncture decompression can be applied. For those patients with difficulties in complete removal of the cyst, e.g., close adhesion between the mediastinal cyst wall and membranous trachea, some cyst wall can be left and treated with ablation using electrocautery. Alternatively, the mucosal membrane can be stripped from the residual cyst wall followed by burning using iodine or anhydrous alcohol in order to prevent the cyst recurrence from the residual cyst wall or mucosal membrane. Granato et al.19) performed complete surgical resection for two cases with using assisted mediastinoscopy. They believed that this technique is appropriate for mediastinal bronchogenic cyst without serious adhesion, infection, and mediastinal surgery history. In addition, the authors placed drainage tube under mediastinoscopy to drain the bronchogenic cyst underneath the keel of the anterior mediastinum. After drainage, sclerosant agent was injected into the cyst through the drainage tube, which also achieved therapeutic efficacy and avoided surgery.20) However, its long-term efficacy cannot be evaluated due to the very few number of cases treated with mediastinoscopy.
Conclusion In addition to mediastinum and lung, bronchogenic cyst can also occur on the chest sidewall outside of pleura, which is extremely rare. No matter what types of imaging was performed, the final diagnosis still relies on pathological examination. Surgical resection is the primary means of treatment for this disease and thoracoscopy-assisted surgery should be preferred.
Disclosure Statement This case report do not exist potential conflict of interest.
References 1) Coselli MP, de Ipolyi P, Bloss RS, et al. Bronchogenic cysts above and below the diaphragm: report of eight cases. Ann Thorac Surg 1987; 44: 491-4. 2) Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors: part II. Tumors of the middle and posterior mediastinum. Chest 1997; 112: 1344-57. 3) Abdul Rahman MR, Yaman MN, Dimon MZ, et al. Pedunculated parietal pleural lesion: a rare presentation of bronchogenic cyst. Ann Thorac Surg 2011; 92: 714-5. 4) McAdams HP, Kirejczyk WM, Rosado-de-Christenson ML, et al. Bronchogenic cyst: imaging features with 373
Wen-Cheng C, et al.
clinical and histopathologic correlation. Radiology 2000; 217: 441-6. 5) St-Georges R, Deslauriers J, Duranceau A, et al. Clinical spectrum of bronchogenic cysts of the mediastinum and lung in the adult. Ann Thorac Surg 1991; 52: 6-13. 6) Kurokawa T, Yamamoto M, Ueda T, et al. Gastric bronchogenic cyst histologically diagnosed after laparoscopic excision: report of a case. Int Surg 2013; 98: 455-60. 7) Cilleruelo Ramos Á, Ovelar Arribas Y, García Yuste M. Cervical bronchogenic cyst in adults. Case report and literature review. Arch Bronconeumol 2015; 51: 95-6. 8) Wang J, Zhu Q, Liang B, et al. Left Ventricular Bronchogenic Cyst. Ann Thorac Surg 2016; 101: 744-6. 9) Marshall ME, Trump DL. Acquired extrinsic pulmonic stenosis caused by mediastinal tumors. Cancer 1982; 49: 1496-9. 10) Zaman MU. Intact bronchogenic cyst presenting as a lung mass provoking a pleural effusion: a rare presentation. W V Med J 2012; 108: 12, 14-5. 11) Schmidt CA, Gordon R, Ahn C. Bronchogenic cyst presenting subsequent to intrapleural rupture. West J Med 1981; 134: 212-4. 12) Okabayashi K, Motohiro A, Ueda H, et al. Subcarinal bronchogenic cyst with high carbohydrate antigen 19-9 production. Jpn J Thorac Cardiovasc Surg 2002; 50: 46-8.
374
13) Nakagawa M, Hara M, Oshima H, et al. Pleural bronchogenic cysts: imaging findings. J Thorac Imaging 2008; 23: 284-8. 14) Chang YC, Chen JS, Chang YL, et al. Video-assisted thoracoscopic excision of intradiaphragmatic bronchogenic cysts: two cases. J Laparoendosc Adv Surg Tech A 2006; 16: 489-92. 15) Kanemitsu Y, Nakayama H, Asamura H, et al. Clinical features and management of bronchogenic cysts: report of 17 cases. Surg Today 1999; 29: 1201-5. 16) Takeda S, Miyoshi S, Minami M, et al. Clinical spectrum of mediastinal cysts. Chest 2003; 124: 125-32. 17) de Perrot M, Pache JC, Spiliopoulos A. Carcinoma arising in congenital lung cysts. Thorac Cardiovasc Surg 2001; 49: 184-5. 18) Martinod E, Pons F, Azorin J, et al. Thoracoscopic excision of mediastinal bronchogenic cysts: results in 20 cases. Ann Thorac Surg 2000; 69: 1525-8. 19) Granato F, Luzzi L, Voltolini L, et al. Video-assisted mediastinoscopic resection of two bronchogenic cysts: a novel approach. Interact Cardiovasc Thorac Surg 2010; 11: 335-6. 20) Kurkcuoglu IC, Eroglu A, Karaoglanoglu N, et al. Mediastinal bronchogenic cyst treated by mediastinoscopic drainage. Surg Endosc 2003; 17: 2028-31.
Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Case Report
Online June 3, 2016 doi: 10.5761/atcs.cr.16-00086
Lipoma-Like Bronchogenic Cyst in the Right Chest Sidewall: A Case Report and Literature Review Wen-cheng Che, MD,1 Qi Zang, MD,2 Qiang Zhu, MD,2 Tian-chang Zhen, MD,2 Gong-zhang Su, MD,2 Peng Liu, MD,3 and Huai-jun Ji, MD4
Bronchogenic cyst most commonly occurs in the mediastinum, followed by the lung. We admitted a 59-year female patient with bronchogenic cyst being uniquely located on the right chest wall of the parietal pleura. Preoperative CT scan showed a local low-density lesion on the right chest wall. The lesion was removed by the thoracoscopic surgery. During the surgical resection, the lesion was observed to be located on the right chest wall. The lesion was surrounded by adipose tissue and covered with entire parietal pleura, which looks like lipoma. Pathological examination demonstrated that the lesion was bronchogenic cyst. In addition, previously reported cases of bronchogenic cyst were reviewed, and the relevant clinical knowledge was discussed. Keywords: foregut cyst, bronchogenic cyst, thoracic cavity, video-assisted thoracic surgery
Introduction Bronchogenic cyst is one of the early embryonic foregut cystic malformations and commonly occurs in the chest cavity. The disease is usually diagnosed in childhood with the lesions most frequently located in the mediastinum and pulmonary parenchyma.1) Although the occurrence of bronchogenic cyst in the parietal pleura has been reported,2,3) it is extremely rare that bronchogenic cyst occurs in the parietal pleura of the side chest wall of thoracic cavity, which looks like lipoma. A Pubmed search from December 1960 to February 2016 showed that the similar cases have not been reported. We reported this Shan Dong University School of Medicine, Jinan, Shandong, China Department of Thoracic Surgery, Qianfoshan Hospital Affiliated to Shandong University, Jinan, Shandong, China 3Taishan Medical University, Taian, Shandong, China 4Weifang Medical University, Weifang, Shandong, China 1 2
Received: March 29, 2016; Accepted: April 22, 2016 Corresponding author: Qiang Zhu, MD. Department of Thoracic Surgery, Qianfoshan Hospital Affiliated to Shandong University, 16766 Jingshi Road, Jinan 250014, Shandong, China Email: [email protected] ©2016 The Editorial Committee of Annals of Thoracic and Cardiovascular Surgery. All rights reserved.
370
case combined with literatures on the diagnosis and treatment of the disease in order to improve the clinician’s awareness of this disease.
Case Report This female patient (59 years old, Han nationality) who has retired from a company was observed to have a mass in the right side of the chest during health physical examination, and was admitted to the hospital on January 4, 2015. The patient did not have a family history of genetic diseases and other special medical conditions. Admission examination showed no positive signs. The preoperative concentration of carcinoembryonic antigen (CEA) was 1.12 ng/mL, neuron-specific enolase (NSE) concentration was 10.76 ng/mL, cytokeratin 19 fragment (CYFRA21-1) concentration was 1.10 ng/mL, squamous cell carcinoma antigen (SCC) concentration was 0.2 ng/mL, and the gastrin releasing peptide precursor (proGRP) concentration was 36.42 pg/mL. The concentration of these tumor markers were within the normal reference range. Chest CT showed low density local area in the chest at the level of sixth and seventh rib. The size of the low density area was approximately 2.8 × 2.5 × 2.3 cm, protruding into the Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Lipoma-Like Bronchogenic Cyst
Fig. 1 (A and B) CT scan showed that the sidewall of the right chest had low density mass (arrow).
discharged from the hospital after 5 days. There was no recurrence during the 1-year follow-up.
Discussion
Fig.2 The mass looks like lipoma under thoracoscopy (arrow).
pleural cavity with a CT value of about –133 Hu. There were no signs of local bone destruction and no obvious abnormalities in lung (Figs. 1A and 1B). This lesion on imaging was manifested as a low-density, smooth edge mass without infiltration into the ribs and intercostal tissue. Therefore, we initially believe that the lesion was a benign lipoma of the chest wall. The tumor mass was removed by thoracoscopy under anesthesia condition. During the surgery, the lesion was observed to be located on the lateral parietal pleura of the right chest wall. The maximum diameter of the mass was about 3.0 cm and it appears as a lipoma (Fig. 2). The parietal pleura covering the surface of the mass was smooth and complete. Pathological examination was performed for the resected tumor mass. Pathological examination showed that the lesion contained fibrous fatty wall structure. The cyst wall was covered with typical pseudostratified ciliated columnar epithelium. Thus, the disease was diagnosed as bronchogenic cyst (Figs. 3A and 3B). After the surgery, the patient was recovered and was Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Foregut cyst was derived from the residual foregut structure during embryonic development. According to the structure of the cyst wall, foregut cysts can be divided into four types: (1) bronchogenic cysts, (2) esophageal duplication cysts, (3) enteric duplication cysts and (4) mixed cysts. Bronchogenic cysts are congenital malformations of the bronchial tree. They are usually located in the proximal end of the trachea or bronchus. The cyst wall was pseudostratified ciliated columnar epithelium that may contain smooth muscle, cartilage and mucous glands. About 85% of bronchogenic cysts are located within the mediastinum,2,4) particularly in areas that are close to the right side of the trachea and carina and hilar.5) In addition, bronchogenic cysts can occur in the lungs, esophagus, stomach wall, paravertebral gutter, skin and subcutaneous area.6) The cysts can also move to atypical sites including neck, myocardium, pericardium, thymus, lung ligament, diaphragmatic and retroperitoneal region, and abdomen.2,4,7,8) Sometime, the cysts may even exhibit a dumbbell shape, with one part being located above the diaphragm and the other part being located below the diaphragm. The bronchogenic cyst in this patient did not occur in any of the typical areas as described above. Instead, it occurs in the inner wall of the chest and the right side of the pleura. Its position is unique, its appearance is atypical, and its lipoma manifestations are also rare. Clinical manifestations of bronchogenic cyst are associated with the cyst location, size and the oppression on its surrounding organs. If the cyst is small and does not oppress its surrounding organs as described in this patient, 371
Wen-Cheng C, et al.
Fig.3 T he inner wall of the cyst was covered with typical pseudostratified ciliated columnar epithelium (arrow: (A) HE staining ×40, (B) HE staining ×200). HE: hematoxylin-eosin
there may be no symptoms and can only be observed during physical examination. When the cysts are large, there may be symptoms of cough, chest tightness, chest pain, difficulty in breathing or swallowing difficulties (with cough being the most common symptoms) due to its oppression on trachea, bronchus, pulmonary or esophageal. A small number of patients have precordial murmur due to the oppression on pulmonary artery by the bulge of the cyst under the hilar pulmonary.9) Patients at younger age are more likely to have the compression symptoms because the trachea and bronchial tree are relatively soft and vulnerable to oppression. Some patients may have acute compression and fever symptoms because of the sudden increase of the cyst after bleeding or secondary infection within the cyst. A few patients have special manifestations, such as pleural effusion, even under the condition of intact cyst without infection or rupture.10) If the cyst penetrates into other adjacent organs, cavities, lung, trachea, esophagus and pleural cavity, symptoms of hemoptysis, hemorrhage or empyema can occur.11) Some patients’ blood carbohydrate antigen CA19-9 was increased, which may be due to the secretion of CA19-9 by the cyst wall epithelial cells.12) CA19-9 concentration was returned to the normal level after cyst resection. Because cases with combination of bronchogenic cyst and an elevated serum CA19-9 concentration are relatively rare, cystic lesions need differential diagnosis. However elevation of serum CA19-9 concentration is helpful for the diagnosis of bronchogenic cyst.13) Identification of the lesions and preoperative localization, and diagnosis rely mainly on imaging examinations. Chest X-ray examination is not helpful for the location of the lesion and diagnosis of the disease. X-ray diagnosis is merely speculative. For those bronchogenic cysts located 372
in the front of the bulge or behind the trachea, esophageal barium meal examination can observe local exogenous pressure trace in esophagus, but it is not easy to distinguish from esophageal cysts. CT scan is very helpful to determine the location of bronchogenic cyst and its relationship with the trachea and bronchus, as well as the compression of the cysts on the adjacent organs. CT scan is also helpful for the diagnosis of cyst bleeding and infection. Calcification may occur in approximately 10% of bronchogenic cysts. CT is very accurate for the diagnosis of cyst wall calcification. The CT value of the cysts can vary from a typical water density (0–20 Hu) to high density (80–90 Hu) according to the material composition of cyst fluid, different content of protein, calcium, and the presence of infection.14) CT scan showed low density (–133 Hu) of the cyst in this patient, which could be due to the low protein content within the cyst fluid and the presence of surface adipose tissue. It is not reliable to differentiate cysts from substantive tumor based merely on the CT value. MRI examination is helpful for the differentiation. Compared to CT, MRI is more sensitive for the diagnosis of bronchogenic cyst and more accurate for the lesion localization. MRI can more clearly show the different tissue components of the cyst. According to the literature, the preoperative CT diagnostic accuracy rate was 69.2%, while MRI diagnostic accuracy rate was 100%.15) Therefore, McAdams et al. suggested that CT is useful for initial evaluation of bronchogenic cysts, while MRI is needed for differentiation of high attenuation cysts from soft tissue masses.4) In the past, we only knew that bronchogenic cysts occur most commonly in the lungs and mediastinum, but never experienced the cases with the cyst located outside of the parietal pleura in the chest cavity. Coupled with the low density area with smooth edges Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
Lipoma-Like Bronchogenic Cyst
in the CT scan, they are usually considered as benign lesions. These cases are therefore misdiagnosed as lipoma, without further MRI examination. Bronchogenic cyst present in chest sidewall also needs to be differentiated from lesions (e.g., pleura lipomas, pleural fibroma, neurogenic tumors, epithelioid hemangioendothelioma, and encapsulated fluid) that have similar imaging presentations. Bronchogenic cysts are pathologically characterized by the ciliated columnar epithelial cells covering the inner surface of the cyst. The inner cyst wall may contain cartilage and smooth muscle component. Presence of typical respiratory epithelium covering the wall is a necessary condition for pathological diagnosis. In contrast, cartilage or muscle components within the cyst are not essential for diagnosis. In the case reported here, the inner surface of cysts was covered with typical respiratory epithelium, however, cartilage or smooth muscle was not observed within the cyst wall. We speculated that this was possibly due to the deterioration of cartilage and smooth muscle during the development of cysts. This also demonstrated that not all of the bronchogenic cysts have typical pathological manifestations. Surgery is the preferred treatment for adults with symptomatic foregut cysts. In contrast, it is still controversial if surgery should be applied for those asymptomatic cysts. Some studies propose dynamic examination for those patients.16) However, multiple studies have shown that foregut cysts (including bronchogenic cyst and esophageal cyst) in old patients may become malignant.17) Furthermore, with the growth of bronchogenic cyst, most patients may have complications,11) which results in complicated disease conditions and surgical difficulties. Therefore, in principle, surgical resection should be applied as early as possible for the patients even without clinical symptoms. Because child has small chest cavity and symptoms can easily occur, surgery should be performed to avoid the interference of cyst on mediastinal organs development. Thoracoscopic resection is the preferred surgery for bronchogenic cyst, because it has the advantage of less trauma and quicker recovery.14) Thus, it is generally the accepted surgery. For the patient in this report, we used thoracoscopy-assisted surgical resection, which results in a successful recovery after the surgery. The patient was discharged from the hospital after only 5 hospitalized days. However, thoracoscopy-assisted surgical resection is not appropriate for patients with preoperative complications, severe adhesion between the lesions and important structures, and injuries during operation.18) If the cysts are Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
large and affect resection, puncture decompression can be applied. For those patients with difficulties in complete removal of the cyst, e.g., close adhesion between the mediastinal cyst wall and membranous trachea, some cyst wall can be left and treated with ablation using electrocautery. Alternatively, the mucosal membrane can be stripped from the residual cyst wall followed by burning using iodine or anhydrous alcohol in order to prevent the cyst recurrence from the residual cyst wall or mucosal membrane. Granato et al.19) performed complete surgical resection for two cases with using assisted mediastinoscopy. They believed that this technique is appropriate for mediastinal bronchogenic cyst without serious adhesion, infection, and mediastinal surgery history. In addition, the authors placed drainage tube under mediastinoscopy to drain the bronchogenic cyst underneath the keel of the anterior mediastinum. After drainage, sclerosant agent was injected into the cyst through the drainage tube, which also achieved therapeutic efficacy and avoided surgery.20) However, its long-term efficacy cannot be evaluated due to the very few number of cases treated with mediastinoscopy.
Conclusion In addition to mediastinum and lung, bronchogenic cyst can also occur on the chest sidewall outside of pleura, which is extremely rare. No matter what types of imaging was performed, the final diagnosis still relies on pathological examination. Surgical resection is the primary means of treatment for this disease and thoracoscopy-assisted surgery should be preferred.
Disclosure Statement This case report do not exist potential conflict of interest.
References 1) Coselli MP, de Ipolyi P, Bloss RS, et al. Bronchogenic cysts above and below the diaphragm: report of eight cases. Ann Thorac Surg 1987; 44: 491-4. 2) Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors: part II. Tumors of the middle and posterior mediastinum. Chest 1997; 112: 1344-57. 3) Abdul Rahman MR, Yaman MN, Dimon MZ, et al. Pedunculated parietal pleural lesion: a rare presentation of bronchogenic cyst. Ann Thorac Surg 2011; 92: 714-5. 4) McAdams HP, Kirejczyk WM, Rosado-de-Christenson ML, et al. Bronchogenic cyst: imaging features with 373
Wen-Cheng C, et al.
clinical and histopathologic correlation. Radiology 2000; 217: 441-6. 5) St-Georges R, Deslauriers J, Duranceau A, et al. Clinical spectrum of bronchogenic cysts of the mediastinum and lung in the adult. Ann Thorac Surg 1991; 52: 6-13. 6) Kurokawa T, Yamamoto M, Ueda T, et al. Gastric bronchogenic cyst histologically diagnosed after laparoscopic excision: report of a case. Int Surg 2013; 98: 455-60. 7) Cilleruelo Ramos Á, Ovelar Arribas Y, García Yuste M. Cervical bronchogenic cyst in adults. Case report and literature review. Arch Bronconeumol 2015; 51: 95-6. 8) Wang J, Zhu Q, Liang B, et al. Left Ventricular Bronchogenic Cyst. Ann Thorac Surg 2016; 101: 744-6. 9) Marshall ME, Trump DL. Acquired extrinsic pulmonic stenosis caused by mediastinal tumors. Cancer 1982; 49: 1496-9. 10) Zaman MU. Intact bronchogenic cyst presenting as a lung mass provoking a pleural effusion: a rare presentation. W V Med J 2012; 108: 12, 14-5. 11) Schmidt CA, Gordon R, Ahn C. Bronchogenic cyst presenting subsequent to intrapleural rupture. West J Med 1981; 134: 212-4. 12) Okabayashi K, Motohiro A, Ueda H, et al. Subcarinal bronchogenic cyst with high carbohydrate antigen 19-9 production. Jpn J Thorac Cardiovasc Surg 2002; 50: 46-8.
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Ann Thorac Cardiovasc Surg Vol. 22, No. 6 (2016)
