A 35-year-old nonsmoker male patient presented to the outpatient department with symptoms of rapidly progressive dyspnoea, facial puffiness, and voice-hoarseness developing over a span of 15 days prior to presentation. There was no history of any haemoptysis, abnormal swelling, breathing difficulty, headache, dizziness, tinnitus, epistaxis, or tuberculosis in the past. His overall past medical and surgical history was uneventful.
On examination, the patient was tachypneic with stable vitals. There was a characteristic plethoric face with periorbital and upper body edema with dilated veins over the anterior wall of the chest and neck. There was no pallor, clubbing, lymphadenopathy, ptosis, or any signs of Horner's syndrome. On thoracic auscultation, there were decreased breath sounds in the third and fourth intercostal spaces in the right parasternal area and infraclavicular areas. The rest of the systemic examination was within normal limits.
His blood investigations at presentation revealed hemoglobin level of 11.5 gm/dL, total leukocyte counts of 8500 cells/mm3, and platelet counts of 3,20,000/mm3. His serum electrolytes, renal function tests, and liver function tests were within normal range. Germ cell tumor markers like lactate-dehydrogenase (LDH), alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin (beta-HCG) levels were within normal limits. Bone marrow examination did not show any malignant marrow infiltration. Serology was negative for human immunodeficiency virus (HIV), viral hepatitis B and C.
Contrast-enhanced computed tomography (CT) of the thorax showed an enhancing well-defined soft tissue density lesion of size 10.3 x 9.3 cm involving superior mediastinum, with compression of trachea, SVC, right upper lobe bronchus, and its branches (Figure 1(a)). The mass was also seen encasing the right brachiocephalic trunk, right subclavian artery, and right common carotid artery.
Histopathological examination of the biopsy specimen was characterized by a monotonous proliferation of tumor cells with oval to spindle, vesicular nuclei surrounded by an indistinct rim of amphophilic to lightly eosinophilic cytoplasm (Figure 1(b)). Immunohistochemistry of the biopsied sample showed positive reactivity to vimentin (Figure 1(c)) and S-100 (Figure 1(d)), epithelial membrane antigen, cytokeratin AE1/AE3, bcl-2, and E-cadherin. Negativity was established for CD34. Cytogenetic analysis by fluorescent in situ hybridization (FISH) sample showed the t(X:18) translocation abnormality. So by combining the histopathological features, IHC, and cytogenetic analysis, diagnosis of monophasic synovial sarcoma was confirmed.
Patient was initially managed symptomatically with diuretics, dexamethasone, oxygen inhalation, and propped up position for symptomatic superior vena cava syndrome. Palliative radiotherapy was omitted owing to the radioresistance of sarcomas. Three cycles of neoadjuvant chemotherapy (ifosfamide 2400 mg/m2 on days 1-5 and doxorubicin 37.5 mg/m2 on days 1 and 2) were given. Patient tolerated chemotherapy well, and there was partial response to the above mentioned chemotherapeutic drugs according to the RECIST criteria. Surgical excision of the mediastinal mass was carried out via a median sternotomy incision. Postoperative recovery was uneventful.
On cut section, the tumor was composed of gray-white to tan homogeneous soft tissue with focal areas of gelatinous consistency, as well as areas of hemorrhage and necrosis. Histopathological appearance was characterized by a monotonous proliferation of tumor cells with oval to spindle, vesicular nuclei surrounded by an indistinct rim of amphophilic to lightly eosinophilic cytoplasm. Thus the diagnosis of monophasic type of synovial sarcoma of the mediastinum was reconfirmed. The resected surgical margins were free of tumor (R0 resection). Patient was managed postoperatively with adjuvant postoperative radiotherapy (50 Gray in 25 fractions over 5 weeks), followed by three more cycles of chemotherapy. After completion of treatment, the patient is under regular surveillance and for the past one year remains free of recurrence.