Poster
# 15
Poster |
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6th Internet World Congress for Biomedical Sciences |
Jesus Gonzalez Garcia(1), Marcial García Rojo(2), Francisco Martín Dávila(3), Rafael López Pérez(4), Margarita Delgado Portela(5), Manuel Carbajo Vicente(6)
(1)(2)(3)(4)(5)(6)Servicio de Anatomía Patológica. Complejo Hospitalario de Ciudad Real - Ciudad Real. Spain
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[Orthopedics & Traumatology] |
[Pathology] |
Synovial sarcoma is a clinic and morphologically well delineated entity representing among 6-10% of the total soft tissue sarcomas (1). They are usually located in paraarticular regions frequently in close relation with tendon sheaths and bursas. Primarily intraarticular synovial sarcomas are rare and most of the descriptions describe extraarticular tumors with a secondary intraarticular growth (2,3,4). Rare times, synovial sarcomas are found in tissues without near synovial structures, such as head and neck (specially in retrofaringeal area), oral cavity, retroperitoneum, anterior abdominal wall, mediastinum and intravascular.
Because of its similar morphologically appearance with synovyum, this neoplasm was first named as "synovioma" by Smith in 1927 (5). Later, Knox, in 1936 (6) proposed the term "synovial sarcoma" although hitherto never have been demonstrated a convincing origin in this membrane and so some authors believe that this neoplasm is actually a "carcinosarcoma"(7).
The neoplasm appears clinically as a deep but palpable painful mass in more than half of the cases, sometimes with some although not usually severe functional alterations. Other clinical symptoms are close related with anatomic position of the neoplasm, such as dysphagia and dysnea in head and neck location.
Because of its usually slow and insidiously growth, diagnosis and treatment is frequently delayed. Discomfort and pain are symptoms reported by the patients some years before diagnosis and is not unusual an erroneous diagnosis of synovitis, bursitis or arthritis.
Synovial sarcoma is a neoplasm of adolescents and young adults between 15 and 35 years old. Usually is found in extremities, in vicinity of the articulations, mainly the knee and in close relation with tendon sheaths and bursas, Primarily intraarticular tumors are rare, accounting for less of 10% of cases.
Histologically, two types are described, a biphasic synovial sarcoma in which fusocellular and epithelial component are represented and a monophasic type, usually fusocellular and much less frequently made up by epithelial cells only with scarcely biphasic areas. Also a poorly differentiated variety is recognised in which serious diagnostic problems may rise, reaching up to 20% of total synovial sarcomas (8). Meis-Kindblom subdivide this later type into three subgroups: a.- a giant cell variant; b.- a small cell variant and c.- a high grade fusocellular variant (9).
Ultrastructurally, cells with epithelial characteristics (bands of paranuclear tonofilaments, pseudoglandular luminas with microvilli, intercellular bindings as "macula adherens" and hemidesmosomes), fusiform cells reminiscent to fibroblasts, and "intermediate" cells can be recognized. Cells with paranucler bands of tonofilaments can be observed.
Immunohistochemically, neoplastic cells are strongly reactive to citokeratins not only in epithelial but also in fusiform areas. Virtually, all biphasic synovial sarcomas show reactivity to citokeratins and EMA. In monophasic fusocellular neoplasms citokeratin reactivity decrease to 60-70% and to 40% in poorly differentiated tumors. Normal or reactive synoviocytes do not express citokeratin immunoreactivity. Citokeratin panel can be a helpful diagnostic tool to separate them from other soft tissue sarcomas that can be positive to CK 8 and 18 but not usually with al CK7 and 19, citokeratins founded in synovial sarcomas (10,11,12)
There is S100 reactivity in 30-40% of synovial sarcomas. Although CD99 (MIC2) and bcl2 can be expressed, these antigens may be found in other soft tissue pathology or tumors (13,14,15,16) and so they are irrelevant for differential diagnosis panel. Synovial sarcomas are negative to CD34.
In 90-95% of cases, synovial sarcomas are related to a characteristic chromosome translocation t(X,18) (P11.2; q11.2). The point of rupture involves two SSX genes (chromosome X) and a SYT gene (chromosome 18). As a result of SSX-SYT fusion new chimeric genes appear. Each tumoral phenotype is related to a point of rupture, so monophasic neoplasms have the breakpoint within SSX2 region and biphasic ones, with extensive epithelial component, within SSX region (17,18,19).
Differential diagnosis include nodular and localized synovitis, pigmented villonodular synovitis and synovial chondromatosis. Nodular and localized synovitis may have clefts lined by cells (synoviocytes) with morphologic appearance similar to cells of synovial sarcoma but they haven´t epithelial characteristics, there are not glandular structures and cellular component is not so homogeneous than observed in synovial sarcoma, being more related to hystiocytic or stromal lineage with presence of giant multinucleated cells. Immunohistochemically, they do not express epithelial markers. Pigmented villonodular synovitis is a pathology with a more extensive involvement of the synovial membrane and, histollogically, haemorrhage, hemosiderin deposits and foamy cells can be observed. Only under a clinical point of view, synovial chondromatosis may raise diagnostic difficulties that are easily resolved wit macro and microscopic study. Differential diagnosis of monophasic synovial sarcomas must include fibrosarcomas, malignant schwannomas and leyomiosarcomas. In poorly differentiated neoplasms, lacking of biphasic pattern, differential diagnosis include carcinomas and round cell tumors such as Ewing sarcoma. Sometimes genetic study must be necessary to assure diagnosis, by detecting the characteristic synovial sarcoma translocation.
Prognostic factors related with a better prognosis include extensive osseous metaplasia and/or calcification, young age of patients, a prolonged clinical history before diagnosis (suggesting a low-aggressiveness neoplasm), distal location, a size less of 5 cm. and a mitotic index below 10 figures/10 hpf. On the contrary, a worse prognosis is related to a tumoral size more than 5 cm., a mitotic index above 10 figures/10 hpf, necrosis and dedifferentiated areas mainly if they comprise more than 20% of tumoral mass (1,20,21,22
Five and ten years survival oscillate between 25,2-62,5% and 11,2-30%, respectively. This drop on the survival rate reflects a high tendency of synovial sarcoma to develop late tumoral metastasis.
SS can recur locally or cause distant metastasis, mainly to lungs or lymph nodes. Referred lymph node metastatic rate is of 10-15% of cases. Elective treatment is local removal with broad surgical margins to avoid local recurrences, associated with radiotherapy and/or chemotherapy.
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[Orthopedics & Traumatology] |
[Pathology] |
