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

Abstract

To evaluate the accuracy and reproducibility of subgrouping and grading soft-tissue sarcomas by fine-needle aspiration biopsy (FNAB), a blind review was conducted of 84 FNAB specimens from 77 malignant and 7 benign soft-tissue lesions. Cytomorphologic subgroups included 31 spindle-cell, 24 pleomorphic, 11 myxoid, 7 epithelioid/polygonal, 3 small round cell, and 8 nondiagnostic cases. Malignancies included one lymphoma and 41 primary, 15 recurrent, and 20 metastatic soft-tissue sarcomas. Adequacy was defined as a majority of slides with at least 5 clusters of 10 unobscured cells. Five originally false-negative cases were considered nondiagnostic on review. Sarcoma was recognized in 59 of 64 adequate cases (92%) with available histology; however, the specific histopathologic subtype was identified in only 9 cases (14%). Benign myxoid and spindle-cell lesions were difficult to separate from low-grade sarcomas in 4 cases, and a B-cell lymphoma with sclerosis mimicked a low-grade myxoid sarcoma. The assigned cytologic grade accurately reflected the histologic grade in 90% of sarcomas when segregated into high and low grades. Pleomorphic, small round cell, and epithelioid/polygonal subgroups corresponded to high-grade sarcomas in all cases with only minor noncorrelations. Major grading noncorrelations occurred in 50% of myxoid and 9% of spindle-cell sarcomas. Therefore, attention should be given to specimen adequacy, and caution should be exercised when attempting to grade myxoid and spindle-cell sarcomas by FNAB.

Diagnostic accuracy and limitations of fine‐needle aspiration cytology of bone and soft tissue lesions

“…Our data show that the difficulties with respect to the sampling and interpretation of soft tissue and bone lesions by FNA can be minimized with the use of onsite evaluation, adequate history, and ancillary studies, which increase the diagnostic value of the procedure. 28 This study also identifies some of the additional difficulties of FNA biopsy in diagnosing soft tissue and bone lesions. One of the limitations involves the group of nondiagnostic cases, which includes cases that have atypical cells or are suspicious for malignancy, in addition to cases with inadequate material.…”

Fine Needle Aspiration for Clinical Triage of Extremity Soft Tissue Masses

“…In the indeterminate group, there were six spindle cell lesions, six myxoid-containing tumors, and one well-differentiated liposarcoma. Determining the nature of masses in these categories with FNAC can be difficult and incisional biopsy may be necessary [14,20,25,37,39]. Pathologists should not be reluctant to request more tissue or to establish minimal criteria for specimen adequacy based on number of unobscured cells per slide [10,25].…”

Concordance of histopathologic and cytologic grading in musculoskeletal sarcomas

“…3). Palmer et al 23 achieved a 90% agreement between cytologic and histologic grade when a 2-grade system (low and high) was used. This dichotomization reflects clinical practice.…”

“…This is similar to the subclassification accuracy of 50 -70% achieved in most previously published studies. 6 -11 Palmer et al 23 were only able to successfully subtype 14% of their cases. In our hands, FNA was most accurate in subtyping sarcomas when they possessed a distinctive stromal component.…”

“…In our hands, FNA was most accurate in subtyping sarcomas when they possessed a distinctive stromal component. Palmer et al 23 found myxoid and spindle cell lesions most difficult to classify. In our study, most high-grade sarcomas were malignant fibrous histiocytomas, and these were also most likely to be accurately identified by cytologic analysis.…”