Synovial sarcoma occurring in the pleura and lung is rare [1,2]. Although diverse group of tumors involve the pleura, malignant mesothelioma has dominated the discussion relating to the diagnosis, etiology and management . Primary pleural malignancy other than malignant mesothelioma are uncommon . Here, we report a case of malignant pleuropulmonary synovial sarcoma developed 17 years after allogeneic stem cell transplan-tation. The patient was initially diagnosed as malignant mesothelioma, without any environmental or occupational asbestos exposure. Five months later, the patients presented with soft tissue metastasis that underwent needle biopsy. Pathological examination including
A 22-year-old man presented with progressively worsening chest discomfort when swallowing foods, exertional dyspnea, and a 6 kg-weight loss in our hospital on March 2019. He was born on October 1996, and had been diagnosed with acute myelomonocytic leukemia at 5 years of age. He received induction therapy comprising cytarabine, idarubicin, and etoposide, which resulted in complete remission. After consolidation chemotherapy, he underwent sibling-matched allogeneic bone marrow transplantation on June 2002. His conditioning regimen included total body irradiation (TBI, 12 Gy in 6 fractions) and cyclophosphamide. He was on regularly followed-up and did not present any specific medical problem. The patient lived in a city area with his father, a part-time tour guide. Neither father nor son had any known exposures to asbestos. Moreover, there was no family history of cancer. Without a regular job after graduating high school, the patient was mostly homebound.
Chest imaging revealed an 8 cm×5.2 cm mass in the right middle lobe, pleura, and diaphragm (Fig. 1). Histo-pathology revealed sarcomatoid malignant mesothelioma with positive immunohistochemical staining for calretinin and D2-40 (Fig. 2). Gene expression studies were not done. Moreover, the patient was not considered a candidate for surgical resection because of the extent of the tumor. Systemic chemotherapy was initiated using bevacizumab (15 mg/kg), pemetrexed (500 mg/m2), and cisplatin (75 mg/m2) every 3 weeks. After the first course of chemotherapy, chest pain and dyspnea improved. How-ever, chest CT obtained after the second course of chemotherapy showed increased tumor size (8.2 cm×6.3 cm). Treatment was switched to concurrent chemo radiotherapy (60 Gy in 30 fractions) with weekly carboplatin (to achieve an area under concentration/time curve of 2 mg/mL∙min) and paclitaxel (45 mg/m2), and then to cisplatin (70 mg/m2 on day 1) and gemcitabine (1,000 mg/m2 on days 1 and 8). Unfortunately, his tumor progressed and five months after the initial diagnosis, masses developed in his arm and flank. He underwent biopsy of the soft tissue. Unexpectedly, histopathology revealed synovial sarcoma, with positive
Pleuropulmonary synovial sarcoma is extremely rare, and 37 cases are reported in literature [4-6]. Synovial sarcoma most commonly occur at extremities, close to large joints . Other sites have been reported, including abdominal wall, esophagus, duodenum, heart, kidney, retroperitoneum, lung and pleura [6,7]. These tumors arise from pluripotent mesenchymal cells with a capacity for differentiation into epithelial and/or spindle-shaped cells [1,8], while tumors of the extremities originate in synovial structures. Because of its clinical presentation at unusual site, misinterpretation of the histopathology of pleuropulmonary synovial sarcoma are frequent . Dif-ferential diagnoses should include sarcomatoid carcinoma, pleuropulmonary blastoma, adenocarcinoma, fibro-sarcoma, hemangiopericytoma, and malignant mesothelioma [2,4]. Among the 36 cases reported, 3 patients were diagnosed as malignant mesothelioma . The histopathology of the lung biopsy samples of our case showed some area with sarcomatoid feature and some area stained positive for calretinin. In retrograde, we presume that tissues stained positive for calretinin might be reactive mesothelial cells. Molecular tests are helpful in diagnoses of synovial sarcoma, as chromosomal translocation t(X;18)(
Synovial sarcoma developed as a second malignant neoplasm are rare . Therapeutic radiation is a known causative factor for the development of sarcomas . Occurrence of angiosarcoma, osteosarcoma, fibrosarcoma, and malignant peripheral nerve sheath tumor in the previously irradiated filed have been reported . However, synovial sarcoma developed as a second malignant neoplasm is not well documented. Several cases of synovial sarcoma occurred in the previously irradiated sites [10, 12]. For our case, we presume that TBI have influenced the development of synovial sarcoma. Additionally, allogeneic hematopoietic stem cell transplantation
Optimal treatment of pleuropulmonary synovial sarcoma is not known . Due to the limited number of reported cases, treatments are similar to synovial sarcoma of other sites [4,6]. Surgery is the mainstay of treatment . Synovial sarcoma show moderate chemosensitivity, however, role of chemotherapy for pleuropulmonary synovial sarcoma is hard to evaluate for such a rare condition . Radiotherapy is usually recommended after incomplete resection . Treatment outcome of pleuropulmonary synovial sarcoma was not satisfactory. In the literature review of the published 36 cases, only 14 patients were alive without disease .
In conclusion, we report an extremely rare case of a pleuropulmonary synovial sarcoma developed after allogeneic hematopoietic stem cell transplantation with TBI-based conditioning for childhood leukemia. Diagnostic approach for a soft tissue tumor of the pleura should be made considering the clinical context, as well as morphologic features with appropriate molecular testing.
The authors have no conflict of interest to declare.