- 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;
- typically arises in the legs and knee;
- most often occurs in adolescents and young adults;
- 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)
- 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%);
- X-rays: (see:
calcification of soft tissue);
- hazy, soft tissue density w/ discrete intrinsic calcifications in 30% of cases;
- 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;
- 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 sarcoma,
rhabdomyosarcoma
- 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. Hajdu SI, Shiu MH, Fortner JG: Cancer 1977;39:1201-1217.
Soft tissue tumors of the foot and ankle. Seale KS, Monson D, Hackbarth DA: Foot Ankle 1988;9:19-27.
SYT-SSX gene fusion as a determinant of morphology and prognosis in synovial sarcoma. New Engl J Med 1998;338:153-160.
