Tumors of the Pleura and Lung Developed 17 Years after Allogeneic Bone Marrow Transplantation for Childhood Acute Myelomonocytic Leukemia: Synovial Sarcoma Mimicking Malignant Mesothelioma

Synovial sarcoma occurring in the pleura and lung is extremely rare. We report a case of pleuropulmonary synovial sarcoma as a second malignant neoplasm. The patient had been diagnosed with acute myelomonocytic leukemia at 5 years of age, and received matched sibling donor allogeneic bone marrow transplantation, with total body irradiation and cyclophosphamide conditioning. At 22 years of age, he complained of worsening chest discomfort and exertional dyspnea. Chest CT revealed a huge mass in the right middle lobe, pleura, and diaphragm. The patient was initially diagnosed as sarcomatoid malignant mesothelioma, without any environmental or occupational asbestos exposure. Five months later, the patient presented with soft tissue metastasis and underwent needle biopsy. Pathological examination including SYT-SSX RT-PCR revealed synovial sarcoma, which led to a review of the original tumor findings and confirmed the diagnosis of pleuropulmonary synovial sarcoma. To the best of our knowledge, our patient is the first case of pleuropulmonary synovial sarcoma developed after allogeneic hematopoietic stem cell transplantation.