Primary pulmonary sarcoma with morphologic features of biphasic synovial sarcoma: a case report

Primary Synovial Sarcoma of the Lung

We describe a case of primary pulmonary synovial sarcoma. A 19-year-old man presented with low-grade fever, dyspnea, chest pain and left arm numbness. Chest radiographs revealed a large, well-circumscribed left perihilar mass and a small ipsilateral pleural effusion. Chest computed tomography (CT) revealed a large well-defined, heterogeneous lung mass. Magnetic resonance imaging (MRI) demonstrated a mass of heterogeneous signal intensity on T1-weighted and proton density images, and high signal intensity on short tau inversion recovery (STIR) images. Whole-body bone scintigraphy showed no evidence of skeletal involvement. Abdominal and pelvic CT showed no intra-abominal or pelvic metastases. A CT-guided biopsy provided the diagnosis of monophasic synovial sarcoma. Following four cycles of chemotherapy, integrated F-18 fluorodeoxyglucose positron emission tomography-computed tomography (18F FDG PET/CT) was performed, which demonstrated interval decrease in the size of the lesion and no significant metabolic activity. Surgical resection was then undertaken. Microscopically, the lesion was a high-grade spindle cell sarcoma consistent with monophasic synovial sarcoma. A variant X;18 translocation was identified by cytogenetic analysis and confirmed with metaphase in situ hybridization. The imaging and pathological features of this rare lesion are reviewed.

Primary pulmonary biphasic synovial sarcoma confirmed by molecular detection of a SYT-SSX2 fusion gene: report of 1 case

We experienced a case of primary pulmonary biphasic synovial sarcoma, which was confirmed by immunohistochemistry and molecular testing of SYT-SSX2 fusion transcripts. The patient was a 61-year-old man who presented with a well-defined mass in the left upper lung field on chest radiography. Left upper lobectomy with lymph node dissection was performed. Histological and immunophenotypic features were consistent with biphasic synovial sarcoma. Reverse transcriptase polymerase chain reaction, performed using RNA extracted from frozen tumor samples for the detection of SYT-SSX fusion gene, amplified a single 331-bp fragment that was characteristic of the SYT-SSX2 fusion transcripts. We report a case of primary pulmonary biphasic synovial sarcoma, which was confirmed by SYT-SSX2 fusion transcripts, and present a brief review of the literature on Korean cases.

Primary poorly differentiated monophasic synovial sarcoma of the lung. A case report with immunohistochemical and genetic studies

We describe a case of a poorly differentiated monophasic synovial sarcoma arising in the lung of a 50-year-old man. The tumor, which was located in the right upper lobe, was lobulated, relatively well-circumscribed, and whitish to yellowish in color. Microscopically, it was composed exclusively of ovoid to polygonal or short spindle cells, with a high nuclear to cytoplasmic ratio and relatively scant cytoplasm, arranged in solid sheets or in a hemangiopericytomatous pattern with intervening wiry collagen fibers. At the periphery of the tumor, entrapped benign alveolar epithelium produced a pseudo-biphasic appearance. In some areas, an abundance of keloidal collagen imparted a close resemblance to a solitary fibrous tumor, making it difficult to establish the diagnosis on the initial needle biopsy, although the malignant nature of the tumor was suggested because of nuclear anaplasia. Immunohistochemically, the tumor was positive for cytokeratin AE1/AE3, CAM5.2, EMA, vimentin, bcl-2 protein, calretinin, and CD34. The reverse transcriptase-polymerase chain reaction (RT-PCR), using RNA extracted from fresh-frozen tissue, demonstrated SYT/SSX-1 fusion transcripts, confirming the diagnosis of synovial sarcoma. Microscopic examination demonstrated metastatic deposits in hilar lymph nodes. This case indicates that a primary pulmonary synovial sarcoma, particularly in its poorly differentiated form, is a diagnostically challenging and highly aggressive neoplasm typically found at an advanced stage.

Pulmonary synovial sarcoma with polypoid endobronchial growth: A case report, immunohistochemical and cytogenetic study*

A rare case of primary pulmonary synovial sarcoma with polypoid endobronchial growth in a 42-year-old Japanese woman is described. Left upper sleeve lobectomy was performed for the polypoid tumor measuring 2.5 cm in the left major bronchus and the patient was treated with adjuvant chemotherapy. Three years later, a recurrent tumor was discovered. Microscopically, this tumor was characterized by a proliferation of oval to spindle-shaped cells arranged in sheets and fascicles and covered by the thin normal bronchial epithelium. Immunohistochemically, tumor cells were positive for vimentin, and focally positive for pancytokeratin recognized by AE1/AE3, cytokeratin 7 and epithelial membrane antigen. A chimera gene, SYT-SSX1, was detected. Recently, primary pulmonary synovial sarcoma is an increasingly recognized clinical entity; however, most of these tumors present as a parenchymal mass. The present case is a unique example of primary synovial sarcoma of endobronchial polypoid type. This case suggests that pulmonary synovial sarcoma might originate from bronchial submucosal stromal tissue.

Primary pleuropulmonary synovial sarcoma: reappraisal of a recently described anatomic subset

BACKGROUND

Primary pleuropulmonary synovial sarcoma (SS) is a rare neoplasm and a recently recognized anatomic subset. Its clinicopathologic attributes are not yet well defined.

METHODS

In this study, the clinical and histopathologic features of 12 SS arising in the lung and/or pleura were analyzed.

RESULTS

The neoplasms occurred in 7 men and 5 women, 20-72 years old (median, 31 years), were well circumscribed with a mean size of 7.2 cm, and involved either lung (9 cases), pleura (2 cases), or both (1 case). All the tumors were of monophasic type. Nine showed a classic spindle cell pattern, and three showed predominantly poorly differentiated features. All but one case showed at least focal positivity for epithelial membrane antigen (EMA), a finding characteristic of this tumor. The lack of EMA staining in one case, proven by electron microscopy to be SS, was attributed to the scarcity of material available for immunohistochemical stains. The diagnosis was proven cytogenetically in three cases. Within 2 years, local recurrence developed in 8 patients (75%), 3 of whom developed metastasis (25%). Five patients died of their disease within 2.5 years, 4 of them from uncontrolled local disease.

CONCLUSIONS

The authors conclude that pleuropulmonary SS, although rare, represents a distinct anatomic subset having pathologic features similar to those of its soft tissue counterpart. Its clinical behavior appears more aggressive, perhaps because of relatively later presentation combined with the difficulty in obtaining a wide surgical margin.

PNET-like features of synovial sarcoma of the lung: a pitfall in the cytologic diagnosis of soft-tissue tumors

Fine-needle aspiration (FNA) cytology of soft-tissue tumors is evolving. As more experience is gained, we are becoming aware of potential pitfalls. We describe 2 cases of synovial sarcoma of the lung, primary and metastatic, in patients who had FNA biopsy performed on a lung mass. The cytologic smears showed extremely cellular groups of malignant small round cells, intersected by small blood vessels, with numerous loose single cells, in a background of macrophages and mature lymphocytes. The tumors displayed monomorphic cells forming rosettes and displaying occasional mitoses. A diagnosis of neuroendocrine tumor/primitive neuroepithelial tumor (PNET) was suspected. Furthermore, this suspicion was supported by immunohistochemical stains, which showed positivity for a neuroendocrine marker, Leu 7 (case 1), and for a neural marker, CD 99 (O 13 or HBA 71) (both cases); and negativity for cytokeratins (case 1). The resection specimen of case 1 had mostly tightly packed small round cells, with occasional rosettes, similar to the FNA biopsy, and focal areas composed of spindle cells, organized in a focal fibrosarcoma-like and hemangiopericytoma-like pattern. A balanced translocation between chromosomes X and 18, demonstrated by both karyotyping and fluorescent in situ hybridization (FISH), enabled us to make a diagnosis of synovial sarcoma, which was histologically classified as poorly differentiated. Case 2 was a metastatic biphasic synovial sarcoma of the arm, with a prominent epithelial component. Synovial sarcoma, when composed mainly of small round cells on cytologic smears, is a great mimicker of neuroendocrine/PNET tumors, with light microscopic and immunohistochemical overlap. Awareness of this potential pitfall may aid in preventing a misdiagnosis. Its recognition is of major concern, especially for the poorly differentiated variant, because it is associated with a worse prognosis.