Case Presentation - Winter, 2005

History: 35 year old, female

Specimen Type: Pleural Fluid

This case was provided by an independent physician who wishes to remain anonymous.

NOTE: The diagnosis and analysis for this case study were provided by an independent physician. All conclusions and opinions are those of the physician and not Hologic, Inc.

Cytologic diagnosis: Metastatic synovial sarcoma

Histologic diagnosis: Metastatic synovial sarcoma

Patient follow-up: None available

Synovial sarcoma is a rare disorder, however it comprises 8 to 10% of all sarcomas, making it the fourth most prevalent sarcoma. Roughly 800 new cases are diagnosed in the United States annually. Adults in the third to fifth decades of life are most commonly affected, with a male to female ratio of 3:2 and presentation of lesions within 5 cm of a joint - most often the knee. It is usually a deep, well-circumscribed mass that is slow growing and causes pain in more than half of patients. Since the tumor can be present for many years prior to detection, one quarter of all patients have pulmonary metastases upon initial presentation.

Treatment and prognosis
Treatment of synovial sarcoma is very aggressive. Surgery to remove the tumor and surrounding tissue is performed with efforts made to spare the involved limb. This is followed by radiation, chemotherapy or a combination of the two. Despite resection and irradiation, most patients develop metastases within two years of initial treatment but a delayed period of up to 10 years is not unusual. Lung and skeletal metastases are most common, with distant metastases in about one half of cases.

Five-year survival rates for synovial sarcoma as a whole are 24-64%, while synovial sarcomas involving the head and neck region have a five year survival rate of 47-82%.

FNA biopsy specimens are highly cellular and may display one of two patterns: monophasic or biphasic. The monophasic pattern shows a mixture of single spindle cells with indistinct, fragile cytoplasm and poorly formed clusters that lack a distinct pattern. Some cells may be stripped of cytoplasm. The nuclei are elongated and hyperchromatic with irregular outlines and conspicuous, possibly multiple, nucleoli. The biphasic pattern consists of the features listed above with the addition of polygonal epithelial cells and rare acinar structures. The epithelial cells have round, regular nuclei with smooth chromatin and little or no hyperchromasia. Nucleoli are conspicuous and may be multiple. Mitosis and mast cells are commonly seen in both types of synovial sarcoma with a possible necrotic background. Vimentin and cytokeratin both yield positive results.

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