Introduction: Pleuropulmonary synovial sarcomas are rare soft tissue malignancies. (1-3) Additionally, pleuropulmonary synovial sarcoma metastasis with valvular involvement, which was the case with our patient, is even more rare. We present an unusual case of a 42-year-old female patient with metastatic pleuropulmonary synovial sarcoma prolapsing to the left ventricular cavity and causing mitral valve obstruction.

Case report: 42-year-old female patient with a history of previously resected inguinal synovial sarcoma who underwent radical irradiation and remained stable for 3 years appeared with the following symptoms: cough, dyspnea and hemoptysis. Computed tomography (CT) scan showed a suspected tumor mass within the left inferior pulmonary lobe affecting the mediastinal pleura with infiltration of the left pulmonary vein. CT scan also revealed a 6 cm mass in the left atrium (LA) that prolapsed into the mitral valve. Immediate echocardiography was performed, which showed a left atrial mass measuring 60x27mm prolapsing into the mitral valve and causing valvular obstruction. Mean pressure gradient across the mitral valve was 6 mmHg. Echocardiography revealed normal ventricular systolic function but a dilatated right ventricle with severe pulmonary hypertension. MRI confirmed previous echo findings but showed a more prominent protrusion of the tumor mass to the right atrium through the atrial septal defect. Bronchial biopsy of the tumor mass revealed undifferentiated monomorphic blunt spindle cells with CD 99 positive expression which confirmed the diagnosis of metastatic monophasic synovial sarcoma. Due to a large tumor extension to almost all cardiac chambers, cardiothoracic surgery was not indicated. Patient is considered for further chemotherapy with ifosfamide/doxorubicin.

Conclusion: The aggressive nature of synovial sarcoma makes its early detection difficult. Because of the small number of reported occurrences, there is no consensus regarding optimal therapy. Therefore, it seems worth investigating both optimal surgical procedures and additional chemo-radiotherapy protocols in order to improve the patient’s survival.