Introduction: Soft-tissue sarcomas account for 1% of all malignancies in adults. Typical symptoms comprise a growing and painless mass. Occasionally, the diagnosis is facilitated by secondaries.
Materials and methods: Here we report the first case presented with intracranial hemorrhage caused by a metastasis of a previously unknown synovial sarcoma. The 74-year-old female patient was under anticoagulation for recurrent thrombosis of the right popliteal vein due to compression by the sarcoma, misdiagnosed as Baker's cyst. The brain metastasis was resected, and after an incisional biopsy of the suspected tumor, which confirmed the diagnosis of a synovial sarcoma, an above knee amputation was performed because of the invasion of the neurovascular structures in the popliteal fossa.
Results: The patient died 11 months after the initial event from pulmonary and further brain metastases.
Conclusion: Brain metastases are seldom the primary factor in the management of advanced synovial sarcoma. Initially, the primary tumor was thought to be a benign cyst; we therefore recommend a biopsy/excision of lesions greater than 5 cm in size and with growth tendency to allow appropriate treatment.