Asian Cardiovasc Thorac Ann 2006;14:511-513
© 2006 Asia Publishing EXchange Ltd
Poorly Differentiated Primary Monophasic Synovial Sarcoma of the Lung
Pedro Cascales, MD1,
Abel A Gómez-Caro, MD,
Belen Ferri-Ñíguez, MD2,
María José Roca, PhD,
Juan Torres, PhD,
Pascual Parrilla, PhD1
Department of Thoracic Surgery
1 Department of Surgery
2 Department of Pathological Anatomy, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain
For reprint information contact: Abel A Gómez-Caro, MD Tel: 34 62 753 6654 Fax: 34 96 836 9716 Email: abelitov{at}yahoo.es, Department of Thoracic Surgery, Hospital Universitario Virgen de la Arrixaca, ctra. murcia-cartagena s/n, 30120 El Palmar, Murcia, Spain.
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ABSTRACT
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Primary monophasic synovial sarcoma of the lung is rarely seen in clinical practice. We report the case of a 60-year-old male who underwent a left lower lobectomy for lung sarcoma. The patient received adjuvant therapy after surgery. Diagnosis was confirmed with SYT-SSX2 translocation detection.
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INTRODUCTION
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Lung cancer is the main cause of cancer death in men. Only 0.5% of malignant lung neoplasms arise in the mesenchymal lung tissues, forming the so-called primary pulmonary sarcoma group.1 Leiomyosarcomas, fibrosarcomas, and hemangiopericytomas are the most common histological subtypes of primary pulmonary sarcomas.1,2 Review of the literature yields few reports of such tumors with only isolated cases or small series that often include different types of tumors of this lineage. Diagnosis of sarcomas has been facilitated by the inclusion of molecular biological techniques in pathology and the recent incorporation of cytogenetics in oncological examination.3,4 We report the case of a 60-year-old patient treated for a lung neoplasm by means of lobectomy, and whose final morphological diagnosis was primary monophasic synovial sarcoma of the lung with poorly-defined areas.
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CASE REPORT
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The patient was a 60-year-old man with no known medication allergies and a history of an inferior myocardial infarction and a cerebrovascular accident two years previously. The patient had received an automatic implantable defibrillator because of multiple episodes of poorly tolerated atrial flutter and ventricular tachycardia following the myocardial infarction. The patient was seen in the clinic for a 7-month progressive nonproductive cough and hemoptysis with no other associated signs or symptoms. Analysis was normal, and a plain chest X-Ray demonstrated a lung mass located in the left lower lobe. A computed tomography (CT) (Figure 1
) scan of the chest and abdomen revealed a 6 x 8 cm mass involving the left lower lobe. Mediastinal lymph nodes were clear, and no other abdominal lesions were noted. Fiberoptic bronchoscopy showed no endobronchial lesions although an extrinsic compression of the left main bronchial tree was evident. Transbronchial biopsy indicated an adenocarcinoma with a pattern of clear and spindle cells. Tests for distant metastases, including positron emission tomography and CT scans of the brain, were normal. The patient was scheduled for lung resection by left lower lobectomy and systematic mediastinal dissection. Bronchial stump was free of disease in frozen section during theater time and confirmed in posterior examination. The postoperative recovery was uneventful, and the patient was discharged on day 5 post-surgery.
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Figure 1. CT scan showed a left lower lobe tumor of 6 x 8 cm. No mediastinal lymph nodes were detected.
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Microscopic study of the specimen revealed a well-defined malignant mesenchymal neoplasm with a pattern of diffuse multinodularity and occasional endobronchial growth. In general, the cells were small with scanty cytoplasm, round nuclei, vesicular chromatin, and indistinct nucleoli. The mitotic index was low. In some fields the cells had an elongated morphology forming bundles, and in others a hemangiopericytoma-like pattern was identifiable. The cells were positive for protein S-100, smooth muscle actin and negative for vimentin, keratin, bcl-2, calretinin, CD-99, HMB-45, desmin, h-caldesmon, calponin, myogenin, MOC 31, peripheral nerve growth factor, CD-10, carcinoembryonic antigen, epithelial membrane antigen (EMA), CD-45, CD-31, CD-34, chromogranin, and synaptophysin. Mucin production was not observed with periodic acid-Schiff stain (Figure 2). The patient received 2 cycles of cisplatin and gemcitabine, after which the adjuvant therapy was suspended due to high toxicity. No signs of recurrence or distant metastasis were observed in the patient during 18 months of follow-up.
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Figure 2. Microscopic Analysis; (A) cells with spheric and oval nuclei with poorly-defined cytoplasms in a diffuse or perivascular pattern (HE x 400); (B) immunohistochemical S-100 protein stain showing strong positivity (HE x 200); (C) focal positivity for smooth muscle actin (HE x 200).
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DISCUSSION
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Primary lung sarcomas are rare, and the few series reported in the literature come from hospitals with high patient volumes in chest surgery.2,5 An exhaustive clinical history of the patient as well as diagnostic tests to rule out the metastatic origin of the tumor are essential in the appropriate approach to treatment.
The synovial sarcoma is located in the para-articular regions in young patients in more than 90% of cases. Other locations have been reported such as the retroperitoneum, the heart, mediastinum, abdominal wall, and the lung. Primary sarcomas account for 9% of mesenchymal tumors.2 Location in the chest is mainly in the chest wall, and 40% of lung tumors of uncommon lineage are sarcomas.6 Such tumors are particularly uncommon in the lung; only 50 cases are reported in the literature. Sarcomas usually develop in middle-aged men with a nonspecific clinical picture such as dry cough, hemoptysis, and weight loss. They are tumors with slow growth and the potential to spread into nearby structures; furthermore, related cases of fatal hemoptysis due to pulmonary artery involvement have been reported.2 The endobronchial location is uncommon except in advanced cases of the disease or recurrences.7 Such tumors generally present neither differentiated clinical nor radiographic features. Therefore, diagnosis is usually established through examination of the surgical specimen.5,8
Up to 90% of biphasic synovial sarcomas express positivity for cytokeratin. However, this percentage decreases markedly in the case of monophasic synovial sarcomas. The EMA stain is usually a complementary marker for cases with a keratin negative stain. Other common useful markers in the case of monophasic synovial sarcomas are the S-100 protein (Figure 2A
), smooth muscle actin (Figure 2B), bcl-2, and CD-99. Such tumors can also show positivity for 2–100 protein and desmin.
Recently, molecular biology and cytogenetic techniques have been introduced into pathology study. Such techniques have led to a better understanding of the biology of synovial sarcomas, in which the translocation t(X;18) (p11,2;q11,2) has been widely studied. This translocation consists of fusion of the SYT gene from chromosome 18 to the genes SSX1 and SSX2 in the region Xp11 thus forming a SYT-SSX1 or SYT-SSX2 fusion transcript that alters the cellular transcription.3,4 The biphasic types usually express the SYT-SSX1 gene fusion while the monophasic type may express both. The presence of SYT-SSX2 is only expressed by the monophasic types indicating a better prognosis.3 Detection of this anomaly in the tumor has a diagnostic sensitivity of 100%.4
The optimum outcome is obtained through an aggressive surgical approach as the sarcomatous nature of these tumors shows a high degree of resistance to radiotherapy and chemotherapy.2,5 The prognosis of synovial sarcomas does not differ from sarcomas of other locations. Risk factors for a poor prognosis include an age of more than 20 years, female sex, incomplete resection, tumor size greater than 5 centimeters,5 tumor necrosis, high number of mitoses, and the absence of SYT-SSX1.2,5 Survival of patients with synovial sarcomas at 5 years is approximately 40%–57%, and 30% at 10 years. Tumor development is slow and local recurrence rate is reported at up to 60% in some series after complete resection.
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REFERENCES
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ABSTRACT
INTRODUCTION
