A 56-year-old male presented to our hospital with a six-month history of dyspnea and back pain, without coughing or shortness of breath. Physical examination revealed nothing of significance in the chest and abdominal regions, as well as in the extremities. During a routine workup, chest X-ray in double projection (posterior–anterior and left lateral) revealed a round mass in the right thoracic cavity, causing a remarkable mediastinal enlargement (Fig. 1). The location of this mass was the middle to posterior mediastinum using a classification by Felson. Then, the patient underwent a whole body multi-detector computed tomography (MDCT, Brilliance CT 16-slice Philips Medical systems, Best, The Netherlands) with i.v. IC87114
medium, which defined the presence of a 13 cm enhanced mass in the upper-right region of the chest. The lesion appeared as firmly adherent to the lateral mediastinal pleural surface, to the posterior wall of trachea and to the lateral wall of esophagus, and no cleavage was found between the mass and the carina or the right
bronchus. Moreover, no sign of pleural effusion or lymphadenopathy was found (Fig. 2a–d). Following, a flexible bronchoscopy was performed, showing an extrinsic compression of the right upper lobe bronchus but the broncho-alveolar lavage (BAL) was negative for malignant cells. Then, the patient underwent thoracotomy, which revealed a large lesion arising from the right costo-vertebral space, not belonging to the lung but adherent to the mediastinal pleura. The histopathological analysis of the excised mass revealed poorly differentiated spindle-like tumor cells
arranged in bundles. Despite the lesion had been confirmed as a malignant mesenchymal tumor at pathology, the exact subtype was hard to define. Immunohistochemistry showed strong positive staining for vimentin, cytokeratin 8, cytokeratin 19 and focally positive for cytokeratin 7 and EMA, and negative for CD34, C5/6, calretine and primary pulmonary tumor marker (TTF-1), which combined with the morphological profile confirmed the diagnosis of mediastinal poorly differentiated monophasic synovial sarcoma. The patient is still alive, disease-free, in good health, currently undergoing follow-up.