Myxoid monophasic synovial sarcoma: case report of an unusual histological variant.

We report the case of a 61-year-old woman who presented a recurrent myxoid synovial sarcoma involving the right ankle and foot. This tumor, defined as a synovial sarcoma showing more than 50% myxoid change in the stroma, has only recently been described as a rare histological variant. The histological diagnosis is particularly difficult in such cases, as the one we are describing, where the tumor is entirely myxoid and monophasic raising the possibility of other myxoid soft tissue neoplasms, such as extraskeletal myxoid chondrosarcoma, malignant peripheral nerve sheath tumor or leiomyosarcoma. On the basis of morphological and immunophenotypical findings, the diagnosis of myxoid synovial sarcoma should be properly established, especially in view of its unusual clinical course and treatment. Furthermore, we will discuss the clinicopathological and immunohistochemical features observed in our case.