Case 1 -
Primary Pericardial Synovial Sarcoma
Martha B. Pitman, Massachusetts General Hospital, Boston, MA
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40 year old Asian male with chronic cough and shortness of breath is found to have a large anterior mediastinal mass.
Primary Pericardial Synovial Sarcoma
Initial FNA was scant and only direct smears were made. The relatively bland spindle cell population
was interpreted as probably representing a spindle cell thymoma, but it was recommended to obtain
additional tissue so that definitive ancillary tests could be performed. Detailed imaging studies
identified a large, centrally necrotic mass with a connection to the pericardium. A repeat biopsy
procedure obtained a core biopsy in addition to smears which showed a predominantly spindle cell tumor
with only focal epithelioid areas. Ancillary testing included immunohistochemical stains which showed
the tumor cells to be CD99 positive, focally positive for EMA and keratin, and negative for S100. smooth
muscle actin, desmin, and calretinin. The diagnosis was clinched with FISH analysis that demonstrated
the diagnostic SYT-SSX break-apart signal corresponding to the t(X;18)
translocation. The patient was surgically debulked with positive margins of a 17.5 cm synovial sarcoma
that involved the pericardium and left ventricle, filled the anterior mediastinum and invaded the fatty
thymus. The patient is alive 4 months post-op and receiving chemotherapy.
The initial cytology diagnosis of a spindle cell thymoma was reasonable as tumors of the anterior
mediastinum usually fall into one of four groups: 1) thyroid tumors, 2) lymphoma, 3) teratoma and other
germ cell tumors and 4) thymoma. Given that the smears were composed of a pure population of spindle
cells, and no tissue was available for ancillary tests, a generic diagnosis of spindle cell lesion
favoring thymoma was the best answer. Most importantly, however, it was made clear that a specific
diagnosis was not made and that additional tissue needed to be obtained to make a definitive diagnosis.
For patient management, it was important to confirm the diagnosis prior to surgery because some tumors,
such as lymphoma, are non-surgical diseases, and others may require pre-operative chemoradiation.
Primary cardiac tumors are rare and most are benign mesenchymal tumors, most of which are myxomas.
Primary cardiac sarcomas are extremely rare, but in fact, represent the second most common type of
cardiac neoplasm. Only a few hundred cases of primary cardiac sarcoma have been reported in the world
literature. Angiosarcoma is the more common sarcoma encountered, but synovial sarcoma has been reported
arising from the atrium, ventricle and pericardium. Other sarcomas reported include myxofibrosarcoma,
leiomyosarcoma, rhabdosarcoma and liposarcoma, among others.
The mean age for presentation of a cardiac sarcoma is between 30-50 years but they can occur at any
age. The clinical presentation is directly dependent on the size of the tumor, but patients usually
present with dyspnea as the patient presented here. Complete excision is difficult and adjuvant
chemotherapy and radiation therapy are often used. If localized to the heart, orthotopic heart
transplant has been shown to provide long-term survival. Prognosis overall, however, remains poor with a
median survival of 6 months.
FNA of these lesions can be helpful but most lesions require ancillary testing for a specific
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