Fine needle aspiration biopsy of soft tissue sarcomas: utility and diagnostic challenges

The role of fine needle aspiration biopsy (FNAB) as the primary modality for the initial diagnosis of previously undiagnosed soft tissue sarcomas presents several important challenges. Most practicing pathologists are inexperienced with the wide array of soft tissue neoplasms and their morphologic heterogeneity, making them susceptible to misdiagnosis. However, in the hands of experienced cytopathologists, FNAB in conjunction with ancillary techniques has a diagnostic accuracy approaching 95% for the diagnosis of malignancy. FNAB has been shown to have a diagnostic yield nearly identical with core needle biopsy while avoiding significant clinical complications. Nevertheless, FNAB has certain limitations related to the accurate histologic grading and subtyping of certain subgroups of sarcomas. It may also be difficult to accurately distinguish between low-grade sarcomas and benign or borderline cellular lesions, especially in the spindle cell sarcoma subgroup. The aim of this review is to highlight the utility and limitations of FNAB in the primary diagnosis of soft tissue sarcomas, highlight diagnostically challenging lesions, and comment on the limitations of FNAB in providing a "definitive" diagnosis.