Background: Synovial sarcoma usually arises in the extremities of young adults and metastasizes in about 50% of the cases. Fine needle aspiration can reveal those metastases.
Case: A 65-year-old female presented with a solid mass in the left lung from which a fine needle aspirate was taken. Five years earlier her left foot was amputated because of a diagnosis of synovial sarcoma. Aspiration cytology from the lung revealed numerous groups of spindle cells with scant cytoplasm and ovoid nuclei with fine, homogeneous chromatin. Only vimentin was positive. Based on the clinical, cytologic and immunocytochemical studies, a metastasis from synovial sarcoma was considered to be the most accurate cytologic diagnosis.
Conclusion: This case demonstrates the utility of aspiration cytology in the diagnosis of a metastatic tumor, especially in those organs in which a core or open biopsy might be too aggressive.