1. بنام خدا

2. Synovial sarcomas include monophasic, biphasic, and poorly differentiated (“round cell”) variants. Monophasic synovial sarcoma shows considerable morphologic overlap with other spindle cell tumors, synovial sarcoma is a translocation-associated mesenchymal neoplasm that represents around 10% of all soft tissue sarcomas.

3. Synovial sarcoma

5. . Monophasic synovial sarcoma is composed of only one of the two components. In the large majority of cases, this applies to the sarcomatous component, which is easily misdiagnosed as fibrosarcoma, hemangiopericytoma, or some other spindle cell Neoplasm A poorly differentiated form of synovial sarcoma is being increasingly recognized, characterized by a greater degree of cellularity, atypia, and mitotic activity. tumor cells may be spindle, small, or large and clear

6. IHC FOR SYNOVIAL SARCOMA CD99 Vimentin CEA EMA Bcl2 Calponin CK7.14.19 S100

7. Ancillary methods such as reverse transcription– polymerase chain reaction, fluorescence in situ hybridization, and traditional karyotyping may be used to demonstrate the specific translocation t(X;18)(SS18-SSX1/2) and thereby confirm the diagnosis. However, such techniques are expensive, are not available in many laboratories, and may require fresh or frozen tissue. Thus, there has been continued interest in the development of novel immunohistochemical markers for diagnosis

8. DIFFERENTIAL DIAGNOSIS MPNST : half de novo, and half arising from neurofibroma a malignant tumor of soft tissue composed of spindle cells hypercellularity and serpentine shape of the tumor cells arrangement in palisades or whorls perivascular concentration of tumor cells with a plumper shape large gaping vascular spaces, resulting in a hemangiopericytoma-like appearance geographic areas of necrosis with tumor palisading at the edges abundant mitoses often quite monomorphic (similar to fibrosarcoma and monophasic synovial sarcoma) metaplastic tissues in 15% of the cases a variant known as epithelioid MPNST frequently in adults the most common locations: neck, forearm, lower leg, and buttock

9. IHC: *S-100 & Leu7 in 50% of the cases S-100 immunoreactivity tends to be focal and not strong, except in the epithelioid variant of MPNST. Strong and diffuse immunoreactivity for S- 100 protein in a malignant spindle cell tumor with morphologic features suggestive of MPNST should raise the possibility of the alternative diagnosis of malignant melanoma. *nestin, HMGA2 protein, and Sox10: +