Ortho Preferred Malpractice Insurance
Home » Orthopaedics » Synovial Sarcoma

Synovial Sarcoma

- See: Soft Tissue Tumor Menu

- Discussion:
    - 4th most common soft-tissue sarcoma (5 to 10 percent of all cases of soft-tissue sarcoma)
    - tumor derived from the synovial tissues found along fascial planes, periarticular structures, and rarely, in joints;
             - it may involve the sheaths and bursae of the tendons;
    - presentation: 
             - most often occurs in adolescents and young adults;
             - deep, painless soft-tissue mass greater than 5 cm in size is suspicious for a sarcoma;
             - slowly enlarging,  painless juxtaarticular mass is primary manifestation;
             - usually presents as stage IIb lesion in lower limbs;
             - may presents as stage I tumor in hands or feet where it may be confused with a ganglion;
    - cytogenetic translocation: (X; 18) (p11; q11) 
    - synovial sarcomas stain positively for keratin
    - location:
             - typically arises in the legs and knee (knee is the most common location);
             - often close to a joint;
             - in the upper extremity, it is found more commonly on palmar surface;
             - evidence of regional lymph node involvement strongly supports the dx;
             - although synovial cell sarcomas are rare, those that do occur are frequently seen in the foot (12-18%);
             - despite the name, these tumors are usually not intra-articular;

- X-rays: (see: calcification of soft tissue);
    - hazy, soft tissue density w/ discrete intrinsic calcifications in 30% of cases;
    - irregular contours differentiate synovial sarcoma from the phleboliths found in a benign hemangioma
    - periosteal reaction or even bone erosion or invasion;
    - differential diagnosis:
          - spotty calcification may indicate chondroma or hemangioma

- Bone Scans: marked radioisotope uptake;

- MRI:
       - lesion is often adjacent to major neurovascular structures;
       - may involve cyst formation (20%)

- Histology:
    - two forms: biphasic (epitheloid) and monophasic (spindle cell type);
    - biphasic form is composed of both epithelial-cell and spindle-cell components, where as monophasic form can be either epithelial-cell or  spindle-cell type;
         - spindle-cell form:
              - predominate spindle cell component (monophasic synovioma) contains cords of spindle cells which may resemble fibrosarcoma;
              - diff dx:
                      - malignant hemangiopericytoma
                      - fibrosarcoma
                      - spindle-cell squamous-cell carcinoma;
         - epithelioid (w/ glandular component):
              - might be confused with adenocarcinoma;
              - reveals a biphasic pattern: intermixed areas of "glandular" synovial like cells & spindle shaped fibrous cells;
              - this glandular area will stain PAS positive;
              - synovial cells:
                      - have an acinar, ductal, or longitudinally arranged tall columnar cells around acellular "slits" containing mucin;
              - fibrous component:
                      - arranged in the herringbone pattern of fibrosarcoma;

- Prognosis:
    - recurrence rate is high
    - lesion characteristically metastasizes to lymph nodes, bones, and lungs;
           - other sarcomas which spread via lymph nodes include: clear cell sarcoma, epithelioid sarcomarhabdomyosarcoma 
    - 5-year survival rate ranges from 25 to 55 %;

- Treatment
    - low grade lesions: treated w/ wide excision;
    - high grade tumors:
           - requires either radical resection or wide surgical excision plus XRT;
    - if tumors are greater than 8 cm in diameter then consider administering chemotherapy and radiation therapy;
           - radiation therapy may provide local control and can create a pseudocapsule around the tumor;
    - use chemotherapy if there is metastatic disease

Synovial sarcoma.

Tendosynovial sarcoma: a clinicopathological study of 136 cases.

Soft tissue tumors of the foot and ankle.   

SYT-SSX gene fusion as a determinant of morphology and prognosis in synovial sarcoma.