ThinPrep (R) vs. conventional smears in fine-needle aspirations of sarcomas: A morphological and immunocytochemical study

Very limited delta exist describing the characteristics of sarcomas sampled by fine-needle aspiration (FNA) and processed by the ThinPrep(R) (TP) meth od. We compared the cytopathological and immunocytochemical features of sar coma aspirates prepared using both the conventional and TP method We review ed 70 sarcoma FNAs. Samples were first used to prepare conventional smears and the remainder of the specimen was rinsed in Cytolyt(R), The average num ber of slides examined per case was two for the TP method and five for the conventional technique. Immunocytochemistry for different markers was perfo rmed in a subset of cases. Sixty-five cases were positive for sarcoma both by conventional and TP methods. Five cases were positive by one method only . Cellularity was higher on conventional slides. In terms of cytoarchitectu re, TP slides revealed fewer thick clusters, more single cells that were mo re evenly distributed, and sometimes distortion of expected cellular arrang ements and architectural patterns. Cytomorphological and nuclear details we re better preserved on TP slides. The background of TP slides revealed a re duction of blood but also some loss of necrosis and characteristic backgrou nd tremor features. Immunocytochemical staining revealed superior results o n TP slides. TP and conventional slides showed good correlation. TPs were e xcellent for immunocytochemistry and represent an alternative to convention al smears when expertise in slide preparation is not available. However,; T Ps may require additional experience in the interpretation of sarcomas, mai nly related to the loss of tumor-specific background features. They are use ful as an adjuvant to conventional smears in sarcoma diagnoses, particularl y when special studies are needed. Diagn. Cytopathol. 1999;21,351-354. (C) 1999 Wiley-Liss, Inc.