Asian Cardiovasc Thorac Ann 2005;13:85-87
© 2005 Asia Publishing EXchange Ltd
Thoracic-Abdominal Approach in Primary Pulmonary Synovial Sarcoma
Sandro Zonta, MD,
Federico Lovisetto, MD,
Patrizia Morbini, MD1,
Lorenzo Cobianchi, MD,
Stefano Nazari, MD
IRCCS Policlinico San Matteo Pavia, Department of Surgery
1 Pathology Institute, University of Pavia, San Matteo Pavia, Italy
For reprint information contact: Sandro Zonta, MD Tel: 39 038 250 2530 Fax: 39 038 250 2999 Email: sandrozonta{at}hotmail.com, Istituto di Chirurgia Epatopancreatica, IRCCS Policlinico San Matteo Pavia, P. le Golgi n°1, Pavia 27100, Italy.
 |
ABSTRACT
|
|---|
We report a case of primary synovial sarcoma of the lung. The patient was a 32-year-old male who presented with a mass in the right hemithorax invading the peritoneal cavity. The neoplasm was resected through a thoracic-abdominal approach. The patient is doing well 21 months after surgery. Within the last decade thoracic localizations of synovial sarcoma are an emerging histopathological entity thanks to the molecular analysis of the SYT-SSX fusion gene transcript.
|
INTRODUCTION
|
|---|
Primary pulmonary sarcoma is rare and frequently creates a diagnostic challenge. The estimated relative incidence of primary lung sarcoma to lung cancer is 0.4%.1 This statement is even more true for synovial sarcoma, a pathological entity that mainly arises in the para-articular soft tissues of the extremities of young adults, but as recently reported, affects primarily the lung, the mediastinum, and the heart.2 The use of more sensitive diagnostic tools and techniques, including identification of a tumor’s chromosomal pattern, is probably the main reason for this apparently increasing incidence of the disease. We report a case of primary thoracic synovial sarcoma undergoing surgical resection.
|
CASE REPORT
|
|---|
In January 2000, a 32-year-old patient underwent a right thoracotomy and middle lobe resection in another hospital for a well-defined mass in the right middle lobe without evidence of lymphadenopathy. Pulmonary hemangioma was the histological diagnosis. A few months later, the patient developed right back pain and dyspnea on exertion. After admission to our institute in November 2001, a computed tomography (CT) scan revealed a large hemithorax mass compressing the lower pulmonary lobe and extending into the peritoneal cavity through the diaphragm, reaching the right upper kidney pole and antero-medially displacing the liver.
The patient underwent a thoraco-phrenic-laparotomy and the tumor was resected in bloc with the anterior arch of the 8th to the 11th rib, a portion of the lower pulmonary lobe (a stapled atypical resection) and most of the right hemidiaphragm. A Goretex® patch was used for the reconstruction of the right hemidiaphragm (Figure 1
). The histological examination showed a picture characterized by relatively monomorphous short spindle cells with scant cytoplasm, indistinct cell borders and oval nuclei arranged in irregularly intersecting fascicles or in haphazard fashion. Irregularly ramifying vessels were interposed between neoplastic cell fascicles. Neoplastic infiltration was observed in fibroadipous soft tissue surrounding the neoplastic mass, however the skeletal muscle and bone were not infiltrated. Immunohistochemical assays revealed positivity for epithelial membrane antigen, CD99 antigen, CD56 antigen and focally for citokeratins and S-100 protein. The morphological and immunohistochemical findings highlighted a diagnosis of monophasic synovial sarcoma. Mitotic index was > 10/10 high power fields. Proliferative index evaluated by immunohistochemical stain with Ki67-MB1 antibody was 5% (Figure 2).
View larger version (138K):
[in this window]
[in a new window]
|
Figure 1. Thoraco-phrenic laparotomy and right hemidiaphragm reconstruction using a Goretex® patch (arrow) sutured anteriorly to the 7th rib and posteriorly to the left hemidiaphragm after resection of the tumor mass.
|
|
View larger version (139K):
[in this window]
[in a new window]
|
Figure 2. The tumor was characterized by a dense proliferation of relatively monomorphous spindle cells with indistinct cytoplasm; the vessels were irregularly interposed between neoplastic cell fascicles (Hematoxylin and Eosin stain, original magnification x 200).
|
|
A revision of the histological slides from the first surgical sample highlighted the presence of large, partially thrombosed vessels, intermingled with focal areas of cellular proliferation with morphological characteristics analogous to those described in the neoplastic mass. The patient is doing fine after undergoing adjuvant chemotherapy 21 months after surgery.
|
DISCUSSION
|
|---|
Synovial sarcoma is the third most common histological type of soft tissue tumor of the extremities, preceded by liposarcoma and malignant fibrous histiocytoma. A minority of tumors have however been reported to occur in other anatomical locations such as the lung, mediastinum, heart, abdominal wall, mesentery, retroperitoneal cavity, peritoneal cavity and the head and neck area.
Clinical symptoms and a physical examination are usually not enough to give a correct diagnosis. Radiological findings do not reveal the characteristics of the tumor which can be referred as any type of lung cancer which tends to expand locally towards the chest wall and the mediastinum.1 Histologically, the synovial sarcoma shares a biphasic pattern characterized by the combination of two different cellular components: epithelial cells and fibrosarcoma-like spindle cells. Based on the prevalence of one component over the other, four different morphological subsets are described: biphasic type, monophasic fibrous type, monophasic epithelial type and poorly differentiated type (round cells).
Due to the lack of specific morphological indicators, the diagnosis of synovial sarcoma, especially the monophasic fibrous type, in unusual locations is generally difficult to achieve. The distinction from other neoplasms with spindle cell morphology such as fibrosarcoma, leiosarcoma and malignant peripheral nerve sheath tumor may be a challenge. Moreover, the differential diagnosis between the monophasic synovial sarcoma and the hemangioma or the hemangiopericytoma can be difficult because of the overlapping morphological markers. Since the tumor cells usually display an epithelial phenotype, the diagnosis of synovial sarcoma can be supported by immunohistochemical or ultrastructural demonstration of epithelial features. Nevertheless, in some synovial sarcomas especially in the poorly differentiated type, immunohistochemical expressions of epithelial markers such as cytokeratin and epithelial membrane antigen may be absent. In these situations, cytogenetic analysis is the procedure of choice for a definitive histological characterization especially when no other findings can be discriminated.
Synovial sarcoma is associated with the t (x;18) (p11.2;q11.2) resulting either in the SYT-SSX 1 or SYT-SSX 2 fusion genes and subsequent transcripts. Some evidence suggests that the particular fusion transcript generated by the translocation correlate with both histologic subtype and the clinical behavior of the disease. The efficacy of the cytogenetic analysis is enforced by the reverse transcriptase-PCR (RT-PCR) assay, which can detect the SYT-SSX fusion gene transcript using a fresh tumor specimen or in paraffin embedded tissue. Recently, the identification of the translocation has occurred by means of RT-PCR analysis of the peripheral blood and has been proposed either as a preoperative diagnostic test or as a prognostic and monitoring examination.4 These assays allow for easy application in problematic cases but present a second line technique limited to highly specialized laboratories and are not yet widespread procedures.
Surgical resection presents the leading treatment for synovial sarcomas and the aggressive resection of centrally located primary pulmonary sarcomas is justified in otherwise healthy patients. The aim of surgery is to achieve negative margins and perform a mediastinal lymph node dissection in an effort to adequately stage the patient. Complete resection has been shown in all previous series to be a significant predictor of improved survival.1
Prognostic factors for survival in primary synovial sarcoma include primary tumor size (< 5 cm vs > 10 cm), margin of resection (clean vs microscopic positive) and mean mitotic activity (> 10 mitoses per 10 high-power fields vs < 10 mitoses per 10 high-power fields), with overall cancer specific survival for localized synovial sarcoma reaching 34% at 10 years.5 Clear evidence of preoperative and adjuvant chemotherapy or radiotherapy efficacy is not reported in the literature as the patients treated were selected and not randomized. However patients who present with incomplete resection, invaded margins, lymph node involvement and high grade or large tumors should undergo adjuvant chemotherapy or radiotherapy.1
Primary pulmonary synovial sarcoma is an emerging clinical and histopathological entity. The diagnostic procedure nowadays is well defined on the basis of morphological and molecular findings, which allow detection especially among the neoplasm characterized by spindle cell morphology. This is probably the reason for the recent increasing evidence in unusual locations such as the lung.
|
REFERENCES
|
|---|
- Porte HL, Metois DG, Leroy X, Conti M, Gosselin B, Wurtz A. Surgical treatment of primary sarcoma of the lung. Eur J Cardiothorac Surg
2000;18:136–42.[Abstract/Free Full Text]
- Witkin GB, Miettinen M, Rosai J. A biphasic tumor of the mediastinum with features of synovial sarcoma. A report of four cases. Am J Surg Pathol
1989;13:490–9.[Medline]
- Attanoos RL, Appleton MA, Gibbs AR. Primary sarcomas of the lung: a clinicopathological and immunohistochemical study of 14 cases. Histopathology
1996;29:29–36.[Medline]
- Hashimoto N, Myoui A, Araki N, Asai T, Sonobe H, Hirota S, et al. Detection of SYT-SSX fusion gene in peripheral blood from a patient with synovial sarcoma. Am J Surg Pathol
2001;25:406–10.[Medline]
- Singer S, Baldini EH, Demetri GD, Fletcher JA, Corson JM. Synovial sarcoma: prognostic significance of tumor size, margin of resection and mitotic activity for survival. J Clin Oncol
1996;14:1201–8.[Abstract/Free Full Text]
TOP
ABSTRACT
INTRODUCTION
