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Schwannoma of the Pulmonary Artery
CLINICAL SPOTLIGHT
Clinical Spotlight
Schwannoma of the Pulmonary Artery Kristen Elstner, MBBS a,∗ , Emily Granger, MBBS, FRACS a , Stephanie Wilson, MBBS(Hons), PhD, FRACP b , Nirmala Kumaradevan, MBBS, FRCPA, FRCPath(UK) c , Melvin Chew, MBBS, FRANZCR d and Craig Harris, MBBS, FRANZCR d a
Department of Cardiothoracic Surgery, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia b Department of Cardiology, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia c Department of Pathology, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia d Norwest Medical Imaging, Suite 3-9, 6 Meridian Place, Norwest Business Park, Bella Vista, NSW 2153, Australia
Schwannoma (neurilemmoma) originating from the pulmonary artery has not before been described. A 65 year-old male presented with dyspnoea on exertion. CT scan was negative for pulmonary thromboembolism, but showed a well circumscribed, heterogeneous mass, 52 mm × 45 mm × 41 mm, straddling the left pulmonary artery and compressing the left atrium. The mass was found at surgery to be originating from the lateral wall of the left pulmonary artery. The tumour was completely resected, and the pulmonary artery reconstructed. The mass was found to be a benign schwannoma on histopathology. (Heart, Lung and Circulation 2013;22:231–233) © 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved. Keywords. Neurilemmoma; Pulmonary artery; Neoplasm
Introduction
P
rimary tumours of the pulmonary vasculature are rarely seen. Most are poorly differentiated, highly fatal sarcomas of the large main pulmonary arteries and veins. Sarcomas of the great vessels are extremely rare, with less than 250 documented cases of pulmonary arterial sarcoma in the world literature [1]. Due to their rarity and their clinical presentation, primary tumours of the pulmonary arteries are easily misdiagnosed as more common diseases such as chronic pulmonary thromboembolism. More common primary mediastinal tumours include foregut cysts, lymphomas and neurogenic neoplasms [2]. We present a patient with a mass originating from the pulmonary artery, found to be a benign schwannoma on histology. Schwannomas (neurilemmomas) are benign neurogenic tumours, and can potentially occur in any peripheral nerve. In the thorax, schwannomas are generally found in the chest wall and posterior mediastinum, often originating along the intercostal nerves. Rarely, schwannomas have been found in the middle and superior mediastinum, arising from the main trunks of the intrathoracic vagus, phrenic and recurrent nerves [3–5]. Primary cardiac schwannomas have also been described, although this is also extremely rare with only nine cases Received 19 February 2012; accepted 16 July 2012; available online 9 August 2012 ∗
Corresponding author. Tel.: +61 02 8382 1111; fax: +61 02 8382 3613. E-mail address: [email protected] (K. Elstner).
reported in the world literature [6]. A schwannoma of the pulmonary artery has not before been documented to the best of our knowledge.
Case Presentation A 65 year-old male presented with complaints of shortness of breath on exertion. Physical examination was unremarkable. Pre-operative computed tomography (CT) pulmonary angiography was negative for pulmonary thromboembolism. However, the patient was noted to have a large mediastinal mass, measuring approximately 40–45 mm in axial diameter, straddling the left pulmonary artery and compressing the left atrium and left atrial appendage (Fig. 1). The lower margin of the lesion lay lateral to the left main stem and left anterior descending artery. There were areas of heterogeneous enhancement within the mass itself on administration of intravenous contrast. The origin of the mass was unable to be determined due to its size and position. Coronary angiography confirmed the presence of significant obstructive coronary artery disease, with no evidence of extrinsic compression of the coronary arteries by the mediastinal mass. Transthoracic echocardiogram was unremarkable. Relevant background includes several risk factors for cardiac disease, as well as diagnosis of an unspecified type of systemic vasculitis and paraproteinaemia, for which he had taken prednisolone and azathioprine in the past. He ceased all immunosuppression over six months prior to this presentation.
© 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved.
1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2012.07.012
232
Elstner et al. Schwannoma of the Pulmonary Artery
Heart, Lung and Circulation 2013;22:231–233
CLINICAL SPOTLIGHT
Figure 1. Computed tomography image demonstrating a heterogeneous mass, 4 cm in axial diameter, straddling the left pulmonary artery.
Patient proceeded to elective resection of the mass and coronary artery bypass surgery through a median sternotomy approach. Approximately the size of a golf ball, the lesion was attached to the lateral wall of the left pulmonary artery, compressing the left atrial appendage and left superior pulmonary vein (Fig. 2). The phrenic and vagus nerves were identified and were not involved in the lesion. The encapsulated mass was completely resected, and a portion of the pulmonary artery was resected along with the tumour at its point of origin. The pulmonary artery was reconstructed using a pericardial patch. The operation then proceeded with cardiopulmonary bypass
Figure 3. Sectioned specimen showing an encapsulated lesion, with areas of necrosis and haemorrhage, with a solid pale central nodule.
and triple vessel coronary artery bypass grafting without further complication. Post-operatively, the patient did not demonstrate any signs or symptoms that would suggest involvement of the phrenic, recurrent laryngeal, or vagus nerves. There was no elevation of the left hemidiaphragm on chest X-ray, nor was he short of breath when lying supine. He did not experience any alteration in voice, and he did not display any impairment of swallowing or gastrointestinal motility. The morphological and immunophenotype of the mass were consistent with a benign schwannoma. Macroscopically, it was a 52 mm × 45 mm × 41 mm encapsulated lesion with a smooth fibrous capsule, with both solid and cystic material inside (Fig. 3). It had a firm solid pale central nodule. Microscopically, it was an encapsulated spindle cell lesion, with hyalinized vessels throughout (Fig. 4) and areas of both hypo- and hyper-cellularity. The central portion of the specimen contained prominent ectatic vessels and showed cystic degeneration. The spindled cells stained positive for S-100 (Fig. 5) and negative for smooth muscle actin and neurofilament stains. It appeared to be completely excised, with no evidence of malignancy.
Discussion
Figure 2. Intra-operative photograph displaying the encapsulated mediastinal mass.
Symptoms and signs of mediastinal masses are nonspecific and are usually caused by the effects of the masses compressing on surrounding structures. Insidious onset of retrosternal chest discomfort, dysphagia, or dyspnoea is often an important clue to the presence of a
Figure 4. Photomicrograph demonstrating spindled cells and multiple hyalinized blood vessels (10×).
Elstner et al. Schwannoma of the Pulmonary Artery
233
reported arising from cardiac tissue, as well as large nerve trunks within the middle and superior mediastinum [3–6]. Radiologically, schwannomas are sharply demarcated, smooth, round masses. Cross-sectional CT imaging shows a heterogeneous mass, with areas of low cellularity, cystic change, haemorrhage and occasionally small areas of calcification. Peripheral enhancement is common after administration of contrast medium. A definite diagnosis of schwannoma can only be made histologically. A distinct capsule, the presence of Antoni A and/or Antoni B areas, and strong immunoreactivity for S-100 protein are criteria for the histologic diagnosis of schwannoma. Microscopically, schwannomas display a mixture of two distinct growth patterns. Antoni A areas are highly cellular and consist of compact bundles of spindleshaped cells lining up in palisades. Antoni B areas are less densely cellular, have a loosely arranged connective tissue matrix, and are prone to degeneration. Vessels with hyalinized walls are common within these areas. Macroscopically, schwannomas are firm, grey masses but may have areas of cystic change and a yellow, xanthomatous appearance. Typical features include necrosis, haemorrhage and cystic degeneration. Surgical resection of schwannoma is the treatment of choice. Complete excision is often possible given the presence of a capsule. Preservation of the involved nerve is theoretically feasible given that the tumour grows adjacent to the nerve fibres, attached only to the peripheral layers of the nerve.
References
Figure 5. Intense immunoreactivity of S-100 stain (red chromogen) (40×). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
mediastinal mass. In about half of cases, symptoms are absent, and the mass is detected incidentally. Physical findings vary depending on the nature and location of the mass. Neurogenic tumours represent approximately 21% of all adult primary mediastinal tumours; the vast majority of these being of nerve sheath origin (schwannomas and neurofibromas) [7]. Malignant neurosarcoma, also a nerve sheath tumour, is much less common. Schwannomas arise from perineural Schwann cells. They grow adjacent to the parental nerve but extrinsic to the nerve fascicles. In most cases, schwannomas are solitary lesions, but multiple lesions may be occasionally seen. They are slow growing and very rarely undergo malignant transformation. The usual site of origin of mediastinal schwannoma is an intercostal nerve or the sympathetic chain, generally within the posterior mediastinum. Uncommonly, they have been
[1] Blackmon SH, Rice DC, Correa AM, Mehran R, Putnam JB, Smythe WR, et al. Management of primary pulmonary artery sarcomas. Ann Thorac Surg 2009;87(3):977–84. [2] Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors. Part II: tumors of the middle and posterior mediastinum. Chest 1997;112(5):1344–57. [3] Huang TW, Yang MH, Cheng YL, Tsai WC, Lee SC. Vagus nerve schwannoma in the middle mediastinum. Thorac Cardiovasc Surg 2010;58(5):312–4. [4] D’Souza B, Lowe A, Stewart B, Roberts T. A rare case of schwannoma of the intrathoracic phrenic nerve. ANZ J Surg 2010;80(11):841–2. [5] Rammos KS, Rammos SK, Foroulis CN, Zaramboukas TK. Schwannoma of the vagus nerve, a rare middle mediastinal neurogenic tumor: case report. J Cardiothorac Surg 2009;4:68. [6] Nakamura K, Onitsuka T, Yano M, Yano Y. Surgical resection of right atrial neurilemmoma extending to pulmonary vein. Eur J Cardiothorac Surg 2003;24(5):840–2. [7] Nason KS, Maddaus MA, Luketich JD. Chest wall, lung, mediastinum, and pleura. In: Brunicardi FC, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE, editors. Schwartz’s principles of surgery. 9th ed. New York: McGraw-Hill; 2010 [chapter 19] http://proxy14.use.hcn.com.au/content.aspx?aID=5016069 [accessed 13.12.11].
CLINICAL SPOTLIGHT
Heart, Lung and Circulation 2013;22:231–233
Clinical Spotlight
Schwannoma of the Pulmonary Artery Kristen Elstner, MBBS a,∗ , Emily Granger, MBBS, FRACS a , Stephanie Wilson, MBBS(Hons), PhD, FRACP b , Nirmala Kumaradevan, MBBS, FRCPA, FRCPath(UK) c , Melvin Chew, MBBS, FRANZCR d and Craig Harris, MBBS, FRANZCR d a
Department of Cardiothoracic Surgery, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia b Department of Cardiology, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia c Department of Pathology, St Vincent’s Hospital, 390 Victoria Street, Darlinghurst, NSW 2010, Australia d Norwest Medical Imaging, Suite 3-9, 6 Meridian Place, Norwest Business Park, Bella Vista, NSW 2153, Australia
Schwannoma (neurilemmoma) originating from the pulmonary artery has not before been described. A 65 year-old male presented with dyspnoea on exertion. CT scan was negative for pulmonary thromboembolism, but showed a well circumscribed, heterogeneous mass, 52 mm × 45 mm × 41 mm, straddling the left pulmonary artery and compressing the left atrium. The mass was found at surgery to be originating from the lateral wall of the left pulmonary artery. The tumour was completely resected, and the pulmonary artery reconstructed. The mass was found to be a benign schwannoma on histopathology. (Heart, Lung and Circulation 2013;22:231–233) © 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved. Keywords. Neurilemmoma; Pulmonary artery; Neoplasm
Introduction
P
rimary tumours of the pulmonary vasculature are rarely seen. Most are poorly differentiated, highly fatal sarcomas of the large main pulmonary arteries and veins. Sarcomas of the great vessels are extremely rare, with less than 250 documented cases of pulmonary arterial sarcoma in the world literature [1]. Due to their rarity and their clinical presentation, primary tumours of the pulmonary arteries are easily misdiagnosed as more common diseases such as chronic pulmonary thromboembolism. More common primary mediastinal tumours include foregut cysts, lymphomas and neurogenic neoplasms [2]. We present a patient with a mass originating from the pulmonary artery, found to be a benign schwannoma on histology. Schwannomas (neurilemmomas) are benign neurogenic tumours, and can potentially occur in any peripheral nerve. In the thorax, schwannomas are generally found in the chest wall and posterior mediastinum, often originating along the intercostal nerves. Rarely, schwannomas have been found in the middle and superior mediastinum, arising from the main trunks of the intrathoracic vagus, phrenic and recurrent nerves [3–5]. Primary cardiac schwannomas have also been described, although this is also extremely rare with only nine cases Received 19 February 2012; accepted 16 July 2012; available online 9 August 2012 ∗
Corresponding author. Tel.: +61 02 8382 1111; fax: +61 02 8382 3613. E-mail address: [email protected] (K. Elstner).
reported in the world literature [6]. A schwannoma of the pulmonary artery has not before been documented to the best of our knowledge.
Case Presentation A 65 year-old male presented with complaints of shortness of breath on exertion. Physical examination was unremarkable. Pre-operative computed tomography (CT) pulmonary angiography was negative for pulmonary thromboembolism. However, the patient was noted to have a large mediastinal mass, measuring approximately 40–45 mm in axial diameter, straddling the left pulmonary artery and compressing the left atrium and left atrial appendage (Fig. 1). The lower margin of the lesion lay lateral to the left main stem and left anterior descending artery. There were areas of heterogeneous enhancement within the mass itself on administration of intravenous contrast. The origin of the mass was unable to be determined due to its size and position. Coronary angiography confirmed the presence of significant obstructive coronary artery disease, with no evidence of extrinsic compression of the coronary arteries by the mediastinal mass. Transthoracic echocardiogram was unremarkable. Relevant background includes several risk factors for cardiac disease, as well as diagnosis of an unspecified type of systemic vasculitis and paraproteinaemia, for which he had taken prednisolone and azathioprine in the past. He ceased all immunosuppression over six months prior to this presentation.
© 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier Inc. All rights reserved.
1443-9506/04/$36.00 http://dx.doi.org/10.1016/j.hlc.2012.07.012
232
Elstner et al. Schwannoma of the Pulmonary Artery
Heart, Lung and Circulation 2013;22:231–233
CLINICAL SPOTLIGHT
Figure 1. Computed tomography image demonstrating a heterogeneous mass, 4 cm in axial diameter, straddling the left pulmonary artery.
Patient proceeded to elective resection of the mass and coronary artery bypass surgery through a median sternotomy approach. Approximately the size of a golf ball, the lesion was attached to the lateral wall of the left pulmonary artery, compressing the left atrial appendage and left superior pulmonary vein (Fig. 2). The phrenic and vagus nerves were identified and were not involved in the lesion. The encapsulated mass was completely resected, and a portion of the pulmonary artery was resected along with the tumour at its point of origin. The pulmonary artery was reconstructed using a pericardial patch. The operation then proceeded with cardiopulmonary bypass
Figure 3. Sectioned specimen showing an encapsulated lesion, with areas of necrosis and haemorrhage, with a solid pale central nodule.
and triple vessel coronary artery bypass grafting without further complication. Post-operatively, the patient did not demonstrate any signs or symptoms that would suggest involvement of the phrenic, recurrent laryngeal, or vagus nerves. There was no elevation of the left hemidiaphragm on chest X-ray, nor was he short of breath when lying supine. He did not experience any alteration in voice, and he did not display any impairment of swallowing or gastrointestinal motility. The morphological and immunophenotype of the mass were consistent with a benign schwannoma. Macroscopically, it was a 52 mm × 45 mm × 41 mm encapsulated lesion with a smooth fibrous capsule, with both solid and cystic material inside (Fig. 3). It had a firm solid pale central nodule. Microscopically, it was an encapsulated spindle cell lesion, with hyalinized vessels throughout (Fig. 4) and areas of both hypo- and hyper-cellularity. The central portion of the specimen contained prominent ectatic vessels and showed cystic degeneration. The spindled cells stained positive for S-100 (Fig. 5) and negative for smooth muscle actin and neurofilament stains. It appeared to be completely excised, with no evidence of malignancy.
Discussion
Figure 2. Intra-operative photograph displaying the encapsulated mediastinal mass.
Symptoms and signs of mediastinal masses are nonspecific and are usually caused by the effects of the masses compressing on surrounding structures. Insidious onset of retrosternal chest discomfort, dysphagia, or dyspnoea is often an important clue to the presence of a
Figure 4. Photomicrograph demonstrating spindled cells and multiple hyalinized blood vessels (10×).
Elstner et al. Schwannoma of the Pulmonary Artery
233
reported arising from cardiac tissue, as well as large nerve trunks within the middle and superior mediastinum [3–6]. Radiologically, schwannomas are sharply demarcated, smooth, round masses. Cross-sectional CT imaging shows a heterogeneous mass, with areas of low cellularity, cystic change, haemorrhage and occasionally small areas of calcification. Peripheral enhancement is common after administration of contrast medium. A definite diagnosis of schwannoma can only be made histologically. A distinct capsule, the presence of Antoni A and/or Antoni B areas, and strong immunoreactivity for S-100 protein are criteria for the histologic diagnosis of schwannoma. Microscopically, schwannomas display a mixture of two distinct growth patterns. Antoni A areas are highly cellular and consist of compact bundles of spindleshaped cells lining up in palisades. Antoni B areas are less densely cellular, have a loosely arranged connective tissue matrix, and are prone to degeneration. Vessels with hyalinized walls are common within these areas. Macroscopically, schwannomas are firm, grey masses but may have areas of cystic change and a yellow, xanthomatous appearance. Typical features include necrosis, haemorrhage and cystic degeneration. Surgical resection of schwannoma is the treatment of choice. Complete excision is often possible given the presence of a capsule. Preservation of the involved nerve is theoretically feasible given that the tumour grows adjacent to the nerve fibres, attached only to the peripheral layers of the nerve.
References
Figure 5. Intense immunoreactivity of S-100 stain (red chromogen) (40×). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)
mediastinal mass. In about half of cases, symptoms are absent, and the mass is detected incidentally. Physical findings vary depending on the nature and location of the mass. Neurogenic tumours represent approximately 21% of all adult primary mediastinal tumours; the vast majority of these being of nerve sheath origin (schwannomas and neurofibromas) [7]. Malignant neurosarcoma, also a nerve sheath tumour, is much less common. Schwannomas arise from perineural Schwann cells. They grow adjacent to the parental nerve but extrinsic to the nerve fascicles. In most cases, schwannomas are solitary lesions, but multiple lesions may be occasionally seen. They are slow growing and very rarely undergo malignant transformation. The usual site of origin of mediastinal schwannoma is an intercostal nerve or the sympathetic chain, generally within the posterior mediastinum. Uncommonly, they have been
[1] Blackmon SH, Rice DC, Correa AM, Mehran R, Putnam JB, Smythe WR, et al. Management of primary pulmonary artery sarcomas. Ann Thorac Surg 2009;87(3):977–84. [2] Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors. Part II: tumors of the middle and posterior mediastinum. Chest 1997;112(5):1344–57. [3] Huang TW, Yang MH, Cheng YL, Tsai WC, Lee SC. Vagus nerve schwannoma in the middle mediastinum. Thorac Cardiovasc Surg 2010;58(5):312–4. [4] D’Souza B, Lowe A, Stewart B, Roberts T. A rare case of schwannoma of the intrathoracic phrenic nerve. ANZ J Surg 2010;80(11):841–2. [5] Rammos KS, Rammos SK, Foroulis CN, Zaramboukas TK. Schwannoma of the vagus nerve, a rare middle mediastinal neurogenic tumor: case report. J Cardiothorac Surg 2009;4:68. [6] Nakamura K, Onitsuka T, Yano M, Yano Y. Surgical resection of right atrial neurilemmoma extending to pulmonary vein. Eur J Cardiothorac Surg 2003;24(5):840–2. [7] Nason KS, Maddaus MA, Luketich JD. Chest wall, lung, mediastinum, and pleura. In: Brunicardi FC, Andersen DK, Billiar TR, Dunn DL, Hunter JG, Matthews JB, Pollock RE, editors. Schwartz’s principles of surgery. 9th ed. New York: McGraw-Hill; 2010 [chapter 19] http://proxy14.use.hcn.com.au/content.aspx?aID=5016069 [accessed 13.12.11].
CLINICAL SPOTLIGHT
Heart, Lung and Circulation 2013;22:231–233