primary pleuropulmonary synovial sarcoma ( ppss ) is a rare soft tissue malignancy representing only 0.1% - 0.5% of all primary lung malignancies . the frequency of cardiac metastasis from soft tissue sarcomas ranges from 3.5% to 35% with only two cases of metastatic synovial sarcoma of the heart reported : one involving the right ventricle and the other the left ventricle . both cases had a primary tumor in the extremities rather than in the lungs without focusing on the imaging findings of these rare lesions ( 2 - 4 ) . we report a case of ppss that eventually metastasized to the heart in a 17-year - old female . a 17-year - old female presented with dull pain in the left upper chest alternating with brief periods of chest discomfort lasting a few months . she had no serious medical or surgical history and grew up in normal residential and social environments . all laboratory data including blood tests , standard biochemical tests , and urinalysis were within normal limits . chest radiographs ( figure 1a and b ) revealed a well - defined round mass in the left upper hemithorax . the mass was at an obtuse angle to the chest wall and was approximately 8 cm long . chest ct ( figure 1c - e ) confirmed a well - defined oval - shaped mass with heterogeneous enhancement in the left upper hemithorax abutting the pleura . in the pre - contrast image , the lesion showed homogeneous soft tissue attenuation and a lack of calcification , but a small amount of high - attenuation fluid was present in the left pleural space , suggestive of hemothorax . after contrast enhancement , the mass showed heterogeneous enhancement , with attenuation similar to that of the back muscles , and contained subtle low densities suggestive of necrosis or hemorrhage . the mediastinal and hilar lymph nodes were not enlarged . in the scanned portion of the abdomen f-18 fluorodeoxyglucose positron emission tomography - ct ( 18f fdg pet / ct ) revealed increased fdg uptake in the mass , with a maximum standardized uptake value of 31.7 ( figure 1f ) . from these imaging findings , the diagnoses of a localized fibrous tumor of the pleura , malignant mesothelioma , metastatic pleural malignancy , and rare primary pulmonary sarcoma ( e.g. , pleuropulmonary synovial sarcoma , fibrosarcoma , leimyosarcoma , sarcomatoid carcinoma , malignant nerve sheath tumor , hemangiopericytoma , and malignant fibrous histiocytoma ) were considered . these diagnoses were based on the tumor s appearance as a sharply marginated , heterogeneously enhanced mass with low attenuation foci and no involvement of the bone or calcifications . ct - guided core needle biopsy of the mass yielded two samples of yellowish gelatinous material . microscopic examination showed relatively uniform spindle - shaped cells with occasional mitoses arranged in tight fascicles . the tumor cells were immunoreactive to vimentin and cd99 and were focally positive for epithelial membrane antigen ( ema ) , suggesting a monophasic synovial sarcoma . medical and surgical oncologists agreed to treat the tumor with surgical resection and to initiate a combination chemotherapy regimen consisting of five cycles of vincristine , doxorubicin , and cyclophosphamide , alternating with four cycles of ifosfamide and etoposide . a thoracotomy was performed , and the mass was found to arise from the visceral pleura and to adhere to the left first to third intercostal spaces , with invasion into the left first intercostal muscle with adjacent hemothorax . the surgical specimen consisted of an 8.0  6.5  5.5 cm well - circumscribed but unencapsulated tumor . the tumor was whitish - yellow , soft , and fleshy with cystic degenerative changes and hemorrhage . histologically , the tumor was composed of densely packed , cellular sheets of spindle cells , and some of the tumor cells were arranged in intersecting fascicles in a herringbone pattern , suggesting fibrosarcoma - like changes ( figure 1 g - h ) . the tumor cells were relatively uniform with ovoid nuclei , scant cytoplasm , and occasional mitotic figures . immunohistochemical staining revealed immunoreactivity of the tumor cells to cytokeratin , ema , and cd99 but not to cd34 or desmin ( figure 1i - j ) . a final diagnosis of a monophasic synovial sarcoma from the visceral pleura was made based on the histological and immunohistochemical findings . she was discharged after surgical resection without complications , after which she underwent adjuvant chemotherapy and radiotherapy . the patient remained stable for 28 months until follow - up contrast - enhanced chest ct revealed a 1.6 cm low attenuation nodule with poor enhancement in the left pericardial area and a small amount of left pericardial and pleural fluid ( figure 2a ) . subsequent 18f fdg pet / ct showed slightly increased fdg uptake in the developing nodule with suspected metastasis . five months after discovery , follow up contrast - enhanced chest ct demonstrated a well - circumscribed polycyclic marginated mass with heterogeneous enhancement in the left pericardial region that had enlarged from 1.6 cm to 5.1 cm ( figure 2b ) . although mri is the most accurate technique for demonstrating cardiac mass , oncologists found the following mri might be ineffective for choosing further treatment for the pericardial mass due to high cost . they had no choice but to do surgery for the mass whether to perform mri or not . therefore , they agreed to operate surgical resection to treat pericardial mass without obtaining cardiac mri . the tumor specimen was a 6.0  5.0  2.0 cm well - circumscribed , whitish - yellowish , fleshy to rubbery mass with zones of necrosis and hemorrhage . the tumor was lateral to the left ventricular wall with invasion into the pericardium , myoendocardium , and endocardium of the left ventricle . microscopically , the tumor contained tight clusters and fascicles of spindle cells with scant cytoplasm , identical to the ppss , confirming a metastatic synovial sarcoma with left pericardial , myoendocardial , and endocardial involvement . after metastatectomy , the patient received adjuvant chemotherapy and radiotherapy . the patient s postoperative period was complicated by recurrent pneumonia . ppss is a rare mesenchymal spindle cell malignancy representing a type of pulmonary sarcoma that comprises 0.1% - 0.5% of all primary lung malignancies . typically , it arises from the chest wall , lung parenchyma , pleura , or mediastinum , but rarely at the level of the bronchial tree , and during the fifth decade of the patient s life ( 1 ) . the 5-year survival rate varies from 36% to 76% ( 6 ) . a small but increasing number of cases of ppss have been reported over the past decades ( 5 ) , but very few of these cases have involved cardiac metastasis . cardiac metastasis from soft tissue sarcomas varies from 3.5% to 35% , with only two cases of metastatic synovial sarcoma of the heart reported : one involving the right ventricle and the other the left ventricle . both of those cases had a primary tumor in the extremities but not in the lung without focusing on the imaging findings of these rare lesions ( 2 - 4 ) . additionally , a literature review of soft tissue sarcomas included only 105 cases of cardiac metastasis . in that review , the predominant histological type was leiomyosarcoma ( 22% ) followed by rhabdomyosarcoma ( 19% ) , and liposarcoma ( 9% ) ; 27% of the cases were unspecified . that report suggested that the clinical manifestation of cardiac metastasis can be subtle , as one - third presented with congestive cardiac failure , which led to other complications such as embolism , tumor thrombus , cardiac tamponade , and arrhythmia ( 2 ) . in our case , the patient was initially asymptomatic except for dull chest pains with only pericardial effusion on follow - up chest ct . symptoms frequently associated with these tumors are chest pain , dyspnea , and cough ; up to 40% of patients are asymptomatic ( 7 ) . the radiological features of ppss are summarized as follows : chest radiographs typically demonstrate a well - defined pleural - based or parenchymal mass - like lesion occasionally associated with ipsilateral pleural effusion . generally , the contralateral lung is not involved . ct and magnetic resonance imaging ( mri ) are relatively useful tools for evaluating ppss , although the findings are nonspecific . the most common ct finding of ppss is a well - defined , heterogeneously enhancing mass often with combined ipsilateral pleural effusion . the inner low - density area often contains necrosis , hemorrhage , or fibrous components . associated lymphadenopathy as well as calcifications , cortical bone destruction , or tumor infiltration of the chest wall and musculature are infrequent . ppss often exhibits heterogeneous high signal intensity on t2-weighted images and iso- or low signal intensity on t1-weighted images . after administering gadolinium differential diagnoses for ppss include metastasis from the extrapulmonary synovial sarcoma , a primary tumor such as a pleural fibroma or mesothelioma , or other primary sarcomatous or sarcomatoid neoplasms . the typical clinical and radiologic features can help narrow down the differential diagnosis of ppss . a history of asbestos exposure and the presence of pleural plaques are indicative of malignant mesothelioma . metastatic disease rarely manifests as a large solitary pulmonary lesion , although many other rare primary sarcomatous or sarcomatoid neoplasms can not be distinguished reliably from ppss based on clinical and radiologic features alone ( 5 ) . monophasic synovial sarcomas are much more common , representing 94% of ppss , and are composed of uniform spindle cells . the surrounding plump spindle cells have hyperchromatic nuclei with scant cytoplasm resembling the tumor cells of monophasic synovial sarcoma . immunohistochemically , most synovial sarcomas show focal expression of cytokeratin and ema . furthermore , 30% are protein s-100 positive , 60% - 70% cd99 positive , and 75% - 100% bcl-2 positive ( 8) . the prognosis of ppss remains uncertain but is usually poor . the 5-year survival rate varies from 36% to 76% depending on the patient s age , tumor size , and tumor resectability ( 6 ) . there is no recommended treatment for ppss , but the mainstay of treatment for all soft tissue sarcomas is surgical resection . aggressive surgery can reduce the tumor size before or after chemotherapy , and complete surgical excision seems to improve the survival of patients with ppss . combination chemotherapy consisting of doxorubicin and ifosfamide has been associated with higher rates of survival in patients with synovial sarcoma ( 6 ) . in summary , ppss is a very rare , aggressive malignancy that must be considered in the differential diagnosis of lung and pleural malignancies . the imaging findings of ppss are nonspecific , and ppss is difficult to confirm based on imaging ; detailed immunohistochemical staining is required for definitive diagnosis . ppss with cardiac metastasis is also extremely rare , and only two such cases have been reported . however , cardiac metastasis of ppss can lead to immediate or delayed death ; therefore , early detection and appropriate management are very important to extend survival .
primary pleuropulmonary synovial sarcomas are rare soft tissue malignancies ; combined metastatic involvement of the heart is extremely rare . in this case report , a 17-year - old female presented with a history of chest pain . 
 chest radiographs revealed a round mass in the left upper hemithorax , and computed tomography ( ct ) showed a well - defined heterogeneous enhancing mass abutting the pleura . 
 a core needle biopsy revealed malignant spindle cells . 
 surgical resection was performed , and a final diagnosis of primary pleural synovial sarcoma , monophasic fibrous type , was made . 
 the patient underwent radical irradiation and chemotherapy and remained stable for 28 months until a follow - up chest ct showed a poorly enhancing nodule in the left pericardial region that enlarged after 5 months . 
 surgical resection was performed . 
 histological examination confirmed metastatic cardiac involvement from a primary pleural synovial sarcoma . 
 we report this unusual case of a primary pleural synovial sarcoma metastasis to the heart .