CASE 106
By: Dr. Nizar Al-Nakshabandi MD, FRCPC
HISTORY: 20-year-old male slowly growing mass in the calf.
What are your findings?
What is the differential diagnosis?
What are the causes?
FINDINGS:
Lateral radiograph [A] demonstrates a possible bulge in the soft tissue with central dystrophic calcification seen.
Axial T1-weighted image [B] through the right leg demonstrates soft tissue mass measuring 5 x 7 cm in the posterior medial aspect of the leg iso-to slightly hyperintense to surrounding muscles with heterogeneity.
Coronal Gradient echo images fat sat [C] confirm the mass and show intralesional hemorrhage within it [blooming artifact].
Sagittal T1 fat-saturated images [D] demonstrate avid diffuse enhancement of the mass lesion. Note that this mass lesion does not involve the neurovascular bundle, does not extend into the joint, and does not cause any bone destruction. No associated lymphadenopathy is detected. An extended view through the lower limbs [not shown here] failed to demonstrate skip lesions
DIFFERENTIAL DIAGNOSIS:
· Synovial sarcoma.
· Malignant fibrous histiocytoma.
· Liposarcoma.
· Metastasizing carcinoma.
· Hemangioma.
DIAGNOSIS:
Synovial sarcoma.
PEARLS AND DISCUSSION:
Synovial sarcoma are high-grade malignant soft tissue tumors that have an indolent course and affects young males. Usually those affected are between 15-40 years of age. It accounts for 5% of all soft tissue sarcomas.
The most common location for these tumors is around and adjacent to large joints such as a knee joint, and therefore the popliteal fossa is a common location. Arising in the joint itself is rare in contrast to the name. Microscopically, they resemble the synovium. Macroscopically, they have nonspecific appearances.
When they spread, they can cause cannonball metastasis to the lungs.
The extremities account for 90% of the cases for location, with the lower limbs accounting for 60-70% of the cases and upper limbs accounting for 20% of the cases. Location in other body parts is extremely rare.
Treatment is combination of surgery and adjuvant radiotherapy and chemotherapy. When clear margins cannot be obtained, then radiotherapy will be administered preoperatively. Being smaller in size and located in the extremity in a younger age group with presence of calcification is a good prognostic value.
Overall, survival can reach 70 %. Distant metastasis is frequent and can reach up to 70% of the cases.
FURTHER READING:
1. Murphey MD, Gibson MS, Jennings BT et-al. From the archives of the AFIP: Imaging of synovial sarcoma with radiologic-pathologic correlation. Radiographics. 26 (5): 1543-65. doi:10.1148/rg.265065084
2. Meyers SP. MRI of bone and soft tissue tumors and tumorlike lesions, differential diagnosis and atlas. Thieme Publishing Group. (2008) ISBN:3131354216
3. O'sullivan PJ, Harris AC, Munk PL. Radiological features of synovial cell sarcoma. Br J Radiol. 2008;81 (964): 346-56. doi:10.1259/bjr/28335824
