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CT imaging of primary pleuropulmonary synovial sarcoma
Clinical Radiology 67 (2012) 884e888
Contents lists available at SciVerse ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
CT imaging of primary pleuropulmonary synovial sarcoma W.-D. Zhang a, Y.-B. Guan b, Y.-F. Chen c, C.-X. Li a, * a
Department of Radiology, State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, PR China Department of Radiology, No.1 Affiliated Hospital, Guangzhou Medical College, Guangzhou, Guangdong, PR China c Department of Surgery, State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, PR China b
article in formation Article history: Received 25 September 2011 Received in revised form 8 February 2012 Accepted 13 February 2012
AIM: To evaluate the computed tomography (CT) imaging findings of primary pleuropulmonary synovial sarcoma. MATERIALS AND METHODS: Five cases of synovial sarcoma confirmed by histopathology and cytogenetic study were retrospectively analysed. All patients had undergone chest radiography and unenhanced and contrast-enhanced CT examinations, and three had also undergone multiphase CT enhancement examinations. Image characteristics, including shape, size, margin, and attenuation of each lesion before and after contrast enhancement, were analysed. RESULTS: The chest radiographs of the five patients showed well-defined or partly welldefined masses, which were homogeneous and without associated calcification or lymphadenopathy. Pneumothorax was present in one patient. The unenhanced CT images showed well-defined, heterogeneous masses with patchy low density in all five patients. The contrastenhanced CT images showed heterogeneous enhancement in all cases, three of which demonstrated cystic and necrotic areas. The tumour showed no prolonged or delayed enhancement in three cases using multiphase CT. There were small pleural effusions in four cases. No calcification was observed in any of the cases. There was no evidence of hilar or mediastinal lymphadenopathy. CONCLUSIONS: In these five patients, primary pleuropulmonary synovial sarcoma presented as a well-defined mass with patchy low density and heterogeneous enhancement, with no evidence of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours. Ó 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Synovial sarcoma is a type of spindle cell tumour that mainly affects the extremities in adolescents and young adults, and accounts for 2.5% w 10% of all soft-tissue sarcomas.1 Synovial sarcomas mainly occur at paraarticular sites, predominantly around the knee joint, and * Guarantor and correspondent: C.-X. Li, State Key Laboratory of Oncology in South China, Department of Radiology, Cancer Center, Sun Yat-sen University, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China. Tel.: þ86 20 87343217; fax: þ86 20 87343392. E-mail address: [email protected] (C.-X. Li).
seldom occur in the head and neck, mediastinum, lung, pleura, and chest wall.2e7 As a result of the difficulty encountered in determining the precise site of origin of pleural or lung synovial sarcomas using imaging or direct surgical visualization, some reports refer to synovial sarcoma arising in these sites as pleuropulmonary synovial sarcomas.5,8,9 Pleuropulmonary synovial sarcoma is a rare malignant tumour and demonstrates more aggressive clinical behaviour than soft-tissue synovial sarcoma.5 There are well-documented radiological reports on synovial sarcoma arising in para-articular sites. However, few reports have focused on pleuropulmonary synovial sarcoma imaging findings.8e10 Herein, the present study
0009-9260/$ e see front matter Ó 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.crad.2012.02.009
W.-D. Zhang et al. / Clinical Radiology 67 (2012) 884e888
885
retrospectively reviewed the radiological findings of five patients with pleuropulmonary synovial sarcoma.
Materials and methods The database of Sun Yat-sen University Cancer Centre was searched and patients who were treated between January 2004 and December 2010 for pleuropulmonary synovial sarcoma were identified. Five patients were found, all of whom had complete clinical and imaging data. An institutional review board exemption and a waiver for the requirement of the written informed consent were obtained in order to perform this retrospective study. Conventional chest radiography and computed tomography (CT) had been performed in all patients. CT imaging was performed using a Brilliance TM16 (Philips Medical Systems, Best, The Netherlands) helical machine. The imaging parameters were as follows: 5 mm section thickness reconstructions, 23 cm field of view, 120 kV voltage, 200 w 300 mA current, and 256 256 matrix. An intravenous bolus dose of 100 ml non-ionic iodinated contrast agent (iopromide; Ultravist; Shanghai, Schering) was administered at a rate of 2.5 ml/s to the patients who underwent contrast-enhanced CT. Contrast-enhanced CT examinations were obtained in two cases after 50 w 60 s of the administration of the contrast agent. In the other three cases, multiphase enhancement images were obtained at 30 s, 60 s, and 180 s after contrast agent injection. Two experienced radiologists reviewed the CT image characteristics of each lesion, which included the location, shape, size, margins, and attenuation of the unenhanced and contrast-enhanced lesions. In the unenhanced CT images, attenuation was classified as low, moderate, or high with respect to the adjacent tissues. Conversely, on contrast-enhanced CT images, the degree of enhancement was classified as none, mild, moderate, or marked enhancement.
Results
Figure 1 Patient 1: posteroanterior chest radiograph shows a large, homogeneous mass in the left hemithorax with rightward shift of the mediastinum (a); contrast-enhanced CT image shows a large mass with heterogeneous enhancement and predominantly cystic areas and a small pleural effusion (b).
Clinical data The study group consisted of four men and one woman, with a mean age of 49 years (range 29 to 70 years). Clinical symptoms included cough (three cases), dyspnoea (two cases), and chest pain (two cases). The laboratory test results of all patients were unremarkable.
Radiographic findings Three tumours were located on the right, and two are on the left. Well-defined or partly well-defined round or oval masses were seen in all patients (Fig 1). All masses were homogeneous, without associated calcification or lymphadenopathy. A mediastinal shift was present in three patients. In one patient, pneumothorax was observed that compressed the lung by 50%. A small pleural effusion was present in three patients.
CT findings CT imaging findings from the five cases are summarized in Table 1. In all five patients, the tumours were round or ovoid. All five tumours were in contact with the pleura. The smallest mass was 6 5 6 cm3, and the largest mass was 14 15 19 cm3. The unenhanced CT images demonstrated well-defined, heterogeneous masses with patchy low density in all five patients. The radiodensity values of the tumours were 20e40 HU on unenhanced CT images. No calcification was observed. The contrast-enhanced CT images showed heterogeneous enhancement in all five cases, three of which demonstrated large patchy cystic and necrotic areas. The radiodensity values of the solid component of masses were 75e88 HU on contrast-enhancement CT images (Fig 2). The tumours showed no prolonged and delayed
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Table 1 Computed tomography findings of five cases of pleuropulmonary synovial tumour. Size (cm3)
Shape
Margin
CT findings
Pleural effusion
Prognosis
13 16 18
Rounded
Well-defined
Small
Remission
12.5 15 13
Rounded
Well-defined
Small
Recurrence
Left lower lobe
656
Rounded
Well-defined
Small
Recurrence
4/39/M
Right middle lobe
8 6.5 5
Rounded
Well-defined
None
Remission
5/70/M
Right upper lobe
14 15 19
Oval
Well-defined
Heterogeneous enhancement with large patchy cystic and necrotic areas Heterogeneous enhancement with patchy cystic and necrotic areas Heterogeneous enhancement with patchy low density, pneumothorax Heterogeneous enhancement with patchy low density Heterogeneous enhancement with large patchy cystic and necrotic areas
Small
Died
Case no./age (years)/sex
Site
1/29/F
Left lower lobe
2/54/M
Right upper lobe
3/54/M
enhancement at 60 and 180 s after contrast administration in three cases with multiphase scan. There was an enhanced irregular peripheral rim in four patients. Small pleural effusions were present in four cases. Pneumothorax was
observed in one patient (Fig 3). There was no evidence of hilar or mediastinal lymphadenopathy. There was no evidence of distant metastases in four patients. One patient had a bone metastasis at diagnosis.
Follow up All five patients received surgery followed by chemotherapy. Three patients underwent pneumonectomy and two patients had a lobectomy. One patient died 3 months after surgery. Two patients presented with a recurrence, 7 and 9 months following surgery. Of these patients, an ipsilateral pleural mass was observed in one (Fig 3), and multiple bilateral lung and pleural metastases were present in the other. The remaining two patients were in remission 12 months to 3 years after surgery.
Microscopy, immunohistochemistry, and cytogenetics All resected tumours were round and well-defined. Four lesions were encapsulated. The cut surfaces were tan/ white or yellowish in colour. Patchy cystic and necrotic areas were observed in all tumours. Histological examination showed that the five tumours were monophasic, which consisted of sheets and fascicles of spindle cells embedded in a variable background of mixoid to densely collagenous elements (Fig 4). Immunohistochemical examination revealed that all five tumours were positive for Bcl-2, and vimentin; four were positive for epithelial membrane antigen (EMA), cytokeratin (CK) and CK7. The immunohistochemical examinations also revealed that all the tumours were negative for CD34. Five cases demonstrated the chromosomal translocation t(x; 18), in which three were the SYT/SSX1 fusion type and two were the SYT/SSX2 fusion type.
Figure 2 Patient 2: contrast-enhanced CT image shows a large mass with heterogeneous enhancement extending to the right upper mediastinum and a small pleural effusion (a); unenhanced CT (lung windows) shows the left lung and right pleural metastasis 7 months post-surgery (b).
Discussion Synovial sarcoma is a mesenchymal spindle cell tumour characterized by the chromosomal translocation t(x;18)(p11;q110), and is thought to be of totipotential
W.-D. Zhang et al. / Clinical Radiology 67 (2012) 884e888
887
Figure 4 Histological examination using light microscopy demonstrating that the tumours consisted of sheets and fascicles of spindle cells (haematoxylin and eosing, 200).
Figure 3 Patient 3: unenhanced CT (lung window) shows a welldefined mass in the right lower lobe with right pneumothorax (a); contrast-enhanced CT image shows a well-defined mass with heterogeneous enhancement abutting the pleura. (b); unenhanced CT shows right pleural metastasis 9 months post-surgery (c).
mesenchymal cell origin.11 Histopathologically, synovial sarcoma can be divided into monophasic and biphasic subtypes, with the monophasic occurring more frequently. Monophasic synovial sarcoma is composed of homogeneous spindle cells with pale-staining nuclei arranged in fascicles and sheets. Biphasic synovial sarcoma is composed of both spindle cells and epithelial cells.
Immunohistochemically, tumour cells stain positive for CK, EMA, Bcl-2, and negative for CD34. Cytogenetic studies have demonstrated the chromosomal translocation t(x;18)(p11;q110), a translocation that fuses the SYT gene located on the long arm of 18 with the SSX1 or SSX2 gene located on the short arm of the X chromosome.11e13 Soft-tissue synovial sarcoma mainly affects adolescents and young adults and has a mild male predominance.1 However, primary pleuropulmonary synovial sarcoma occurs in adults.4 Frazier et al.8 reported an affected group that consisted of five men and seven women with a mean age of 37 years (range 17e68 years). Patients often presented with dyspnoea, chest pain, cough, and back pain.8 In the present series, all patients were adults with a mean age of 49 years and demonstrated a male predominance. The main symptoms were similar to those reported by Frazier et al.8 Pleuropulmonary synovial sarcoma often demonstrates a well-defined mass with patchy low density on unenhanced CT images, and homogeneous or heterogeneous enhancement on contrast-enhanced CT images. On T1weighted magnetic resonance imaging (MRI) images, pleuropulmonary synovial sarcoma often appears isointense with hypointense areas; mixed intense areas, with some tumours demonstrating isointense with hyperintense areas, on T2-weighted MRI images; and heterogeneous enhancement on contrast-enhanced T1-weighted images.8,9 In the present series, the unenhanced CT images showed well-defined or partly well-defined heterogeneous masses with patchy low density in all five patients. The contrast-enhanced CT images showed heterogeneous enhancement in all patients, with the tumours in three cases demonstrating cystic and necrotic areas. The above imaging findings are consistent with previous reports.8,9 To the authors’ knowledge, there were no reports concerning the multiphase CT imaging findings of pleuropulmonary synovial sarcoma. In the present series, the tumour showed no prolonged or delayed enhancement in the three cases that underwent multiphase imaging, which was an unusual manifestation for the most common lesions. Pathological analysis revealed that the cystic and necrotic areas in the
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mass correlated with haemorrhage, necrosis, and cystic change and the patchy low-density areas correlated with the mixoid or collagenous elements. Calcification is a common finding in synovial sarcoma at para-articular sites and can be seen in 30% of lesions.1 However, none in 11 patients with pleuropulmonary synovial sarcomas reported by Frazier et al. had tumour calcification.8 In the present series, no calcification was observed in any of the five patients. All five tumours in the present series were peripheral and were closely related to the pleura, and the resected tumours demonstrated pleural involvement to varying extents. Thus, it is difficult to determine the precise site of lung or pleural origin. Because it is difficult to define and distinguish pleural and pulmonary origin, and also difficult to recapitulate any clearly pleural and pulmonary structure in the tumour, the tumour is referred to as a pleuropulmonary synovial sarcoma by some researchers.5,8,9 Synovial sarcoma often metastasizes via the blood, and rarely via the lymphatic system. None of the patients reported by Frazier et al.8 had lymphadenopathy. In the present series, no lymphadenopathy was observed in any of the five patients, which is consistent with previous reports.8,9 Pleuropulmonary synovial sarcoma is more aggressive than soft-tissue synovial sarcoma, and often demonstrates distant metastases and local recurrence after treatment. Prognosis tends to be poor.4,5,8,9 Surgery is the main method of treatment, accompanied by chemotherapy and radiotherapy. In a report by Essary et al.,5 the frequency of local recurrence was 75% in the first 2 years (n ¼ 12), and five patients died as a result of the disease within 2.5 years. In the present series, one patient died 3 months after surgery. Two patients presented with recurrence, 7 and 9 months, following surgery. The imaging findings of pleuropulmonary synovial sarcoma are non-specific. It needs to be differentiated from other tumours, such as pleural solitary fibrous tumour, malignant mesothelioma, malignant peripheral nerve sheath tumour, pulmonary peripheral fibrosarcoma, leiomyosarcoma, and malignant fibrous histiocytoma.8,9,14,15 Of these, pleural solitary fibrous tumour is the lesion with greatest overlap in imaging features with pleuropulmonary synovial sarcoma. Pleural solitary fibrous tumours also demonstrate well-defined, lobulated isodensity with patchy low density on unenhanced CT images, and mild or marked heterogeneous enhancement on contrast-enhanced CT images. However, pleural solitary fibrous tumours often
demonstrate prolonged, delayed enhancement on multiphase scan,16 which can help to differentiate it from pleuropulmonary synovial sarcoma. In conclusion, pleuropulmonary synovial sarcoma is usually observed as a well-defined mass with patchy low density and heterogeneous enhancement, and no sign of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours.
References 1. Murphey MD, Gibson MS, Jennings BT, et al. From the archives of the AFIP: imaging of synovial sarcoma with radiologicepathologic correlation. RadioGraphics 2006;26:1543e65. 2. Rangheard AS, Vanel D, Viala J, et al. Synovial sarcomas of the head and neck: CT and MR imaging findings of eight patients. AJNR Am J Neuroradiol 2001;22:851e7. 3. Kaira K, Ishizuka T, Sunaga N, et al. Primary mediastinal synovial sarcoma: a report of 2 cases. J Comput Assist Tomogr 2008;32:238e41. 4. Hartel PH, Fanburg-Smith JC, Frazier AA, et al. Primary pulmonary and mediastinal synovial sarcoma: a clinicopathologic study of 60 cases and comparison with five prior series. Mod Pathol 2007;20:760e9. 5. Essary LR, Vargas SO, Fletcher CD. Primary pleuropulmonary synovial sarcoma: reappraisal of a recently described anatomic subset. Cancer 2002;94:459e69. 6. Nakajo M, Ohkubo K, Nandate T, et al. Primary synovial sarcoma of the sternum: computed tomography and magnetic resonance imaging findings. Radiat Med 2005;23:208e12. 7. Fujimoto K, Hashimoto S, Abe T, et al. Synovial sarcoma arising from the chest wall: MR imaging findings. Radiat Med 1997;15:411e4. 8. Frazier AA, Franks TJ, Pugatch RD, et al. From the archives of the AFIP: pleuropulmonary synovial sarcoma. RadioGraphics 2006;26:923e40. 9. Duran-Mendicuti A, Costello P, Vargas SO. Primary synovial sarcoma of the chest: radiographic and clinicopathologic correlation. J Thorac Imaging 2003;18:87e93. 10. Matsuo Y, Sakai S, Yabuuchi H, et al. A case of pulmonary synovial sarcoma diagnosed with detection of chimera gene: imaging findings. Clin Imaging 2006;30:60e2. 11. Aubry MC, Suster S, Tazelaar HD, et al. Pulmonary synovial sarcoma. In: Travis WD, Brambilla E, Muller-Hermelink HK, Harris CC, editors. World Health Organization classification of tumours. Pathology and genetics of tumours of the lung, pleura, thymus and heart. Lyon, France: IARC; 2004. p. 111e2. 12. Park JS, Min BR, Park SH, et al. Primary pulmonary biphasic synovial sarcoma confirmed by molecular detection of a SYT-SSX2 fusion gene: report of 1 case. Korean J Intern Med 2010;25:331e6. Epub 2010 Aug 31. 13. Hosono T, Hironaka M, Kobayashi A, et al. Primary pulmonary synovial sarcoma confirmed by molecular detection of SYTeSSX1 fusion gene transcripts: a case report and review of the literature. Jpn J Clin Oncol 2005;35:274e9. 14. Gladish GW, Sabloff BM, Munden RF, et al. Primary thoracic sarcomas. RadioGraphics 2002;22:621e37. nez A, Franquet T, Prats R, et al. Unusual primary lung tumors: 15. Gime a radiologicepathologic overview. RadioGraphics 2002;22:601e19. 16. Zhang M, Zhou C, Yang ZH, et al. CT findings of solitary fibrous tumors of the chest. Clin Radiol 2008;27:394e7.
Contents lists available at SciVerse ScienceDirect
Clinical Radiology journal homepage: www.clinicalradiologyonline.net
CT imaging of primary pleuropulmonary synovial sarcoma W.-D. Zhang a, Y.-B. Guan b, Y.-F. Chen c, C.-X. Li a, * a
Department of Radiology, State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, PR China Department of Radiology, No.1 Affiliated Hospital, Guangzhou Medical College, Guangzhou, Guangdong, PR China c Department of Surgery, State Key Laboratory of Oncology in South China, Cancer Center, Sun Yat-sen University, PR China b
article in formation Article history: Received 25 September 2011 Received in revised form 8 February 2012 Accepted 13 February 2012
AIM: To evaluate the computed tomography (CT) imaging findings of primary pleuropulmonary synovial sarcoma. MATERIALS AND METHODS: Five cases of synovial sarcoma confirmed by histopathology and cytogenetic study were retrospectively analysed. All patients had undergone chest radiography and unenhanced and contrast-enhanced CT examinations, and three had also undergone multiphase CT enhancement examinations. Image characteristics, including shape, size, margin, and attenuation of each lesion before and after contrast enhancement, were analysed. RESULTS: The chest radiographs of the five patients showed well-defined or partly welldefined masses, which were homogeneous and without associated calcification or lymphadenopathy. Pneumothorax was present in one patient. The unenhanced CT images showed well-defined, heterogeneous masses with patchy low density in all five patients. The contrastenhanced CT images showed heterogeneous enhancement in all cases, three of which demonstrated cystic and necrotic areas. The tumour showed no prolonged or delayed enhancement in three cases using multiphase CT. There were small pleural effusions in four cases. No calcification was observed in any of the cases. There was no evidence of hilar or mediastinal lymphadenopathy. CONCLUSIONS: In these five patients, primary pleuropulmonary synovial sarcoma presented as a well-defined mass with patchy low density and heterogeneous enhancement, with no evidence of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours. Ó 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction Synovial sarcoma is a type of spindle cell tumour that mainly affects the extremities in adolescents and young adults, and accounts for 2.5% w 10% of all soft-tissue sarcomas.1 Synovial sarcomas mainly occur at paraarticular sites, predominantly around the knee joint, and * Guarantor and correspondent: C.-X. Li, State Key Laboratory of Oncology in South China, Department of Radiology, Cancer Center, Sun Yat-sen University, 651 Dongfengdong Road, Guangzhou, Guangdong 510060, PR China. Tel.: þ86 20 87343217; fax: þ86 20 87343392. E-mail address: [email protected] (C.-X. Li).
seldom occur in the head and neck, mediastinum, lung, pleura, and chest wall.2e7 As a result of the difficulty encountered in determining the precise site of origin of pleural or lung synovial sarcomas using imaging or direct surgical visualization, some reports refer to synovial sarcoma arising in these sites as pleuropulmonary synovial sarcomas.5,8,9 Pleuropulmonary synovial sarcoma is a rare malignant tumour and demonstrates more aggressive clinical behaviour than soft-tissue synovial sarcoma.5 There are well-documented radiological reports on synovial sarcoma arising in para-articular sites. However, few reports have focused on pleuropulmonary synovial sarcoma imaging findings.8e10 Herein, the present study
0009-9260/$ e see front matter Ó 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.crad.2012.02.009
W.-D. Zhang et al. / Clinical Radiology 67 (2012) 884e888
885
retrospectively reviewed the radiological findings of five patients with pleuropulmonary synovial sarcoma.
Materials and methods The database of Sun Yat-sen University Cancer Centre was searched and patients who were treated between January 2004 and December 2010 for pleuropulmonary synovial sarcoma were identified. Five patients were found, all of whom had complete clinical and imaging data. An institutional review board exemption and a waiver for the requirement of the written informed consent were obtained in order to perform this retrospective study. Conventional chest radiography and computed tomography (CT) had been performed in all patients. CT imaging was performed using a Brilliance TM16 (Philips Medical Systems, Best, The Netherlands) helical machine. The imaging parameters were as follows: 5 mm section thickness reconstructions, 23 cm field of view, 120 kV voltage, 200 w 300 mA current, and 256 256 matrix. An intravenous bolus dose of 100 ml non-ionic iodinated contrast agent (iopromide; Ultravist; Shanghai, Schering) was administered at a rate of 2.5 ml/s to the patients who underwent contrast-enhanced CT. Contrast-enhanced CT examinations were obtained in two cases after 50 w 60 s of the administration of the contrast agent. In the other three cases, multiphase enhancement images were obtained at 30 s, 60 s, and 180 s after contrast agent injection. Two experienced radiologists reviewed the CT image characteristics of each lesion, which included the location, shape, size, margins, and attenuation of the unenhanced and contrast-enhanced lesions. In the unenhanced CT images, attenuation was classified as low, moderate, or high with respect to the adjacent tissues. Conversely, on contrast-enhanced CT images, the degree of enhancement was classified as none, mild, moderate, or marked enhancement.
Results
Figure 1 Patient 1: posteroanterior chest radiograph shows a large, homogeneous mass in the left hemithorax with rightward shift of the mediastinum (a); contrast-enhanced CT image shows a large mass with heterogeneous enhancement and predominantly cystic areas and a small pleural effusion (b).
Clinical data The study group consisted of four men and one woman, with a mean age of 49 years (range 29 to 70 years). Clinical symptoms included cough (three cases), dyspnoea (two cases), and chest pain (two cases). The laboratory test results of all patients were unremarkable.
Radiographic findings Three tumours were located on the right, and two are on the left. Well-defined or partly well-defined round or oval masses were seen in all patients (Fig 1). All masses were homogeneous, without associated calcification or lymphadenopathy. A mediastinal shift was present in three patients. In one patient, pneumothorax was observed that compressed the lung by 50%. A small pleural effusion was present in three patients.
CT findings CT imaging findings from the five cases are summarized in Table 1. In all five patients, the tumours were round or ovoid. All five tumours were in contact with the pleura. The smallest mass was 6 5 6 cm3, and the largest mass was 14 15 19 cm3. The unenhanced CT images demonstrated well-defined, heterogeneous masses with patchy low density in all five patients. The radiodensity values of the tumours were 20e40 HU on unenhanced CT images. No calcification was observed. The contrast-enhanced CT images showed heterogeneous enhancement in all five cases, three of which demonstrated large patchy cystic and necrotic areas. The radiodensity values of the solid component of masses were 75e88 HU on contrast-enhancement CT images (Fig 2). The tumours showed no prolonged and delayed
886
W.-D. Zhang et al. / Clinical Radiology 67 (2012) 884e888
Table 1 Computed tomography findings of five cases of pleuropulmonary synovial tumour. Size (cm3)
Shape
Margin
CT findings
Pleural effusion
Prognosis
13 16 18
Rounded
Well-defined
Small
Remission
12.5 15 13
Rounded
Well-defined
Small
Recurrence
Left lower lobe
656
Rounded
Well-defined
Small
Recurrence
4/39/M
Right middle lobe
8 6.5 5
Rounded
Well-defined
None
Remission
5/70/M
Right upper lobe
14 15 19
Oval
Well-defined
Heterogeneous enhancement with large patchy cystic and necrotic areas Heterogeneous enhancement with patchy cystic and necrotic areas Heterogeneous enhancement with patchy low density, pneumothorax Heterogeneous enhancement with patchy low density Heterogeneous enhancement with large patchy cystic and necrotic areas
Small
Died
Case no./age (years)/sex
Site
1/29/F
Left lower lobe
2/54/M
Right upper lobe
3/54/M
enhancement at 60 and 180 s after contrast administration in three cases with multiphase scan. There was an enhanced irregular peripheral rim in four patients. Small pleural effusions were present in four cases. Pneumothorax was
observed in one patient (Fig 3). There was no evidence of hilar or mediastinal lymphadenopathy. There was no evidence of distant metastases in four patients. One patient had a bone metastasis at diagnosis.
Follow up All five patients received surgery followed by chemotherapy. Three patients underwent pneumonectomy and two patients had a lobectomy. One patient died 3 months after surgery. Two patients presented with a recurrence, 7 and 9 months following surgery. Of these patients, an ipsilateral pleural mass was observed in one (Fig 3), and multiple bilateral lung and pleural metastases were present in the other. The remaining two patients were in remission 12 months to 3 years after surgery.
Microscopy, immunohistochemistry, and cytogenetics All resected tumours were round and well-defined. Four lesions were encapsulated. The cut surfaces were tan/ white or yellowish in colour. Patchy cystic and necrotic areas were observed in all tumours. Histological examination showed that the five tumours were monophasic, which consisted of sheets and fascicles of spindle cells embedded in a variable background of mixoid to densely collagenous elements (Fig 4). Immunohistochemical examination revealed that all five tumours were positive for Bcl-2, and vimentin; four were positive for epithelial membrane antigen (EMA), cytokeratin (CK) and CK7. The immunohistochemical examinations also revealed that all the tumours were negative for CD34. Five cases demonstrated the chromosomal translocation t(x; 18), in which three were the SYT/SSX1 fusion type and two were the SYT/SSX2 fusion type.
Figure 2 Patient 2: contrast-enhanced CT image shows a large mass with heterogeneous enhancement extending to the right upper mediastinum and a small pleural effusion (a); unenhanced CT (lung windows) shows the left lung and right pleural metastasis 7 months post-surgery (b).
Discussion Synovial sarcoma is a mesenchymal spindle cell tumour characterized by the chromosomal translocation t(x;18)(p11;q110), and is thought to be of totipotential
W.-D. Zhang et al. / Clinical Radiology 67 (2012) 884e888
887
Figure 4 Histological examination using light microscopy demonstrating that the tumours consisted of sheets and fascicles of spindle cells (haematoxylin and eosing, 200).
Figure 3 Patient 3: unenhanced CT (lung window) shows a welldefined mass in the right lower lobe with right pneumothorax (a); contrast-enhanced CT image shows a well-defined mass with heterogeneous enhancement abutting the pleura. (b); unenhanced CT shows right pleural metastasis 9 months post-surgery (c).
mesenchymal cell origin.11 Histopathologically, synovial sarcoma can be divided into monophasic and biphasic subtypes, with the monophasic occurring more frequently. Monophasic synovial sarcoma is composed of homogeneous spindle cells with pale-staining nuclei arranged in fascicles and sheets. Biphasic synovial sarcoma is composed of both spindle cells and epithelial cells.
Immunohistochemically, tumour cells stain positive for CK, EMA, Bcl-2, and negative for CD34. Cytogenetic studies have demonstrated the chromosomal translocation t(x;18)(p11;q110), a translocation that fuses the SYT gene located on the long arm of 18 with the SSX1 or SSX2 gene located on the short arm of the X chromosome.11e13 Soft-tissue synovial sarcoma mainly affects adolescents and young adults and has a mild male predominance.1 However, primary pleuropulmonary synovial sarcoma occurs in adults.4 Frazier et al.8 reported an affected group that consisted of five men and seven women with a mean age of 37 years (range 17e68 years). Patients often presented with dyspnoea, chest pain, cough, and back pain.8 In the present series, all patients were adults with a mean age of 49 years and demonstrated a male predominance. The main symptoms were similar to those reported by Frazier et al.8 Pleuropulmonary synovial sarcoma often demonstrates a well-defined mass with patchy low density on unenhanced CT images, and homogeneous or heterogeneous enhancement on contrast-enhanced CT images. On T1weighted magnetic resonance imaging (MRI) images, pleuropulmonary synovial sarcoma often appears isointense with hypointense areas; mixed intense areas, with some tumours demonstrating isointense with hyperintense areas, on T2-weighted MRI images; and heterogeneous enhancement on contrast-enhanced T1-weighted images.8,9 In the present series, the unenhanced CT images showed well-defined or partly well-defined heterogeneous masses with patchy low density in all five patients. The contrast-enhanced CT images showed heterogeneous enhancement in all patients, with the tumours in three cases demonstrating cystic and necrotic areas. The above imaging findings are consistent with previous reports.8,9 To the authors’ knowledge, there were no reports concerning the multiphase CT imaging findings of pleuropulmonary synovial sarcoma. In the present series, the tumour showed no prolonged or delayed enhancement in the three cases that underwent multiphase imaging, which was an unusual manifestation for the most common lesions. Pathological analysis revealed that the cystic and necrotic areas in the
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mass correlated with haemorrhage, necrosis, and cystic change and the patchy low-density areas correlated with the mixoid or collagenous elements. Calcification is a common finding in synovial sarcoma at para-articular sites and can be seen in 30% of lesions.1 However, none in 11 patients with pleuropulmonary synovial sarcomas reported by Frazier et al. had tumour calcification.8 In the present series, no calcification was observed in any of the five patients. All five tumours in the present series were peripheral and were closely related to the pleura, and the resected tumours demonstrated pleural involvement to varying extents. Thus, it is difficult to determine the precise site of lung or pleural origin. Because it is difficult to define and distinguish pleural and pulmonary origin, and also difficult to recapitulate any clearly pleural and pulmonary structure in the tumour, the tumour is referred to as a pleuropulmonary synovial sarcoma by some researchers.5,8,9 Synovial sarcoma often metastasizes via the blood, and rarely via the lymphatic system. None of the patients reported by Frazier et al.8 had lymphadenopathy. In the present series, no lymphadenopathy was observed in any of the five patients, which is consistent with previous reports.8,9 Pleuropulmonary synovial sarcoma is more aggressive than soft-tissue synovial sarcoma, and often demonstrates distant metastases and local recurrence after treatment. Prognosis tends to be poor.4,5,8,9 Surgery is the main method of treatment, accompanied by chemotherapy and radiotherapy. In a report by Essary et al.,5 the frequency of local recurrence was 75% in the first 2 years (n ¼ 12), and five patients died as a result of the disease within 2.5 years. In the present series, one patient died 3 months after surgery. Two patients presented with recurrence, 7 and 9 months, following surgery. The imaging findings of pleuropulmonary synovial sarcoma are non-specific. It needs to be differentiated from other tumours, such as pleural solitary fibrous tumour, malignant mesothelioma, malignant peripheral nerve sheath tumour, pulmonary peripheral fibrosarcoma, leiomyosarcoma, and malignant fibrous histiocytoma.8,9,14,15 Of these, pleural solitary fibrous tumour is the lesion with greatest overlap in imaging features with pleuropulmonary synovial sarcoma. Pleural solitary fibrous tumours also demonstrate well-defined, lobulated isodensity with patchy low density on unenhanced CT images, and mild or marked heterogeneous enhancement on contrast-enhanced CT images. However, pleural solitary fibrous tumours often
demonstrate prolonged, delayed enhancement on multiphase scan,16 which can help to differentiate it from pleuropulmonary synovial sarcoma. In conclusion, pleuropulmonary synovial sarcoma is usually observed as a well-defined mass with patchy low density and heterogeneous enhancement, and no sign of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours.
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