The authors report a case of a 24 year-old female patient with a three-month history of pain and enlargement of the left halux. Ultrasound showed a heterogeneous, hypoechoic solid soft tissue mass with cystic areas and calcification in the dorsum of the left halux. A tendinous structure was identified within the lesion but no evidence of involvement of adjacent osseous structures was found. Doppler ultrasound revealed central and peripheral hypervascularization of the lesion. Magnetic resonance imaging demonstrated a solid soft tissue mass containing a tendinous structure. The lesion appeared as an intermediate signal intensity structure on T1 images, high signal intensity on T2 images, and showed marked enhancement after intravenous administration of gadolinium. No osseous lesions were identified. The patient was submitted to surgical resection of the lesion in the dorsum of the left halux and the pathology results revealed a monophasic fibrous synovial sarcoma.

Keywords: Synovial sarcomas, Soft-tissue tumors, Ultra-sonography, Magnetic resonance imaging

Intraspinal synovial cysts of the lumbar spine are rare and commonly associated with osteoarthritis of the facet joints, particularly at level L4-L5. Symptoms are uncommon and may include low-back pain or sciatica. These cysts are accurately diagnosed by using computed tomography and magnetic resonance imaging. Diagnosis is essential for the correct management of the cysts. Several treatment options are available including rest and immobilization, computed tomography guided corticosteroids injection, and surgery in patients that are nonresponsive to other treatment methods.

Keywords: Synovial cysts, Computed tomography, Facet joints