The Diagnostic Utility of Fine-Needle Aspiration Biopsy of Soft-Tissue Sarcomas in the Core Needle Biopsy Era

Fine-needle aspiration biopsy (FNAB) is a widely accepted and established diagnostic technique in diagnosing the presence of primary malignancies, metastatic disease, and benign nonneoplastic lesions. However, its role in the evaluation of soft-tissue sarcomas has remained controversial, especially as the primary modality for establishing an initial diagnosis. Arguments in favor of using core needle biopsies (CNB) relate to the fact that such samples provide ample “tissue” for evaluating architectural patterns, as well as a source for performing ancillary studies. However, in the hands of experienced cytopathologists, FNAB in conjunction with ancillary studies (performed on tissue obtained in the form of cell blocks) has been shown to have a diagnostic yield nearly identical to CNB, with an accuracy rate approaching 95% for the diagnosis of malignancy. Additionally, as therapy and prognosis are heavily dependent on the grade and stage of the tumor, it has been shown that approximately 90% of soft-tissue sarcomas can be successfully subtyped and even graded by FNAB. There are, however, certain limitations of FNAB, especially in the workup of low-grade myxoid and spindle cell sarcomas and in their separation from borderline and benign lesions. In these select subgroups, CNB may be more advantageous. Also, in the absence of an on-site cytopathologist for immediate evaluation of the sample and triage of materials for ancillary studies, CNB is preferred, although FNAB can still identify benign soft-tissue lesions and malignancies of nonmesenchymal origin not requiring ancillary studies. This review will focus on the more commonly encountered soft-tissue sarcomas and highlight the advantages and limitations of FNAB in establishing their diagnosis.