Subgrouping and grading of soft-tissue sarcomas by fine-needle aspiration cytology: A histopathologic correlation study

To evaluate the accuracy and reproducibility; of subgrouping and grading so ft-tissue sarcomas by fine needle aspiration biopsy (FNAB), a blind review was conducted of 84 FNAB specimens from 77 malignant and 7 benign soft-tiss ue lesions. Cytomorphologic subgroups included 31 spindle-cell, 24 pleomorp hic, 11 myxoid, 7 epithelioid/polygonal, 3 small round cell, and 8 nondiagn ostic cases. Malignancies included one lymphoma and 41 primary, 15 recurren t, and 20 metastatic soft-tissue sarcomas. Adequacy was defined as a majori ty of slides with at least 5 clusters of IO unobscured cells. Five original ly false-negative cases were considered nondiagnostic on review. Sarcoma wa s recognized in 59 of 64 adequate cases (92%) with available histology; how ever, the specific histopathologic subtype was identified in only 9 cases ( 14%). Benign myxoid and spindle-cell lesions were difficult to separate fro m low-grade sarcomas in 4 cases, and a B-cell lymphoma with sclerosis mimic ked a low-grade myxoid sarcoma. The assigned cytologic grade accurately ref lected the histologic grade in 90% of sarcomas when segregated into high an d low grades. Pleomorphic, small round cell, and epithelioid/polygonal subg roups corresponded to high-grade sal-comas in all cases with only minor non correlations. Major grading noncorrelations occurred in 50% of myxoid find 9% of spindle-cell sarcomas. Therefore, attention should be given to specim en adequacy, and caution should be exercised when attempting to grade myxoi d and spindle-cell sarcomas by FNAB. (C) 2001 Wiley-Liss, Inc.