@entity7465 Amplification in Problematic XXXX : Analysis of FISH Testing Criteria.

@entity1 @entity362 @entity7465 @entity5 @entity75 @entity1821
To discriminate @entity362 from atypical @entity5 /well-differentiated @entity1821 (ALT/WDL) we perform fluorescence in situ hybridization (FISH) for @entity7465 amplification in several problematic situations: " @entity362 " >10 cm, lesions with equivocal atypia, recurrent " @entity362 ," all @entity362 ", and in cases not fitting the above criteria but having worrisome clinical or radiologic features. To ascertain the validity of these criteria, we have reviewed our experience with 301 consecutive differentiated @entity5 in which the diagnosis of ALT could not be established on the basis of histologic sections and in which FISH was performed on the basis of the above criteria. The final diagnosis was based on @entity7465 amplification status. Given the nature of this study to evaluate difficult lesions, most cases included (74%) were received in consultation. This enhanced our study series for borderline cases, and the data presented may not be generalizable to adipocytic @entity5 seen outside a subspecialty setting. Of 301 cases, 108 proved to be ALT/WDL (36%). The most common test indication was size >10 cm (n=187), followed by equivocal atypia (n=145), retroperitoneal/pelvic/abdominal location (n=86), recurrence (n=33), and clinical concern (n=12). Of the @entity5 >10 cm, 68 (36%) proved to be ALT/WDL, whereas the remainder were interpreted as @entity362 or its variants (eg, spindle cell or @entity362 ). The 2 groups did not differ statistically in size, although ALTs consistently occurred in @entity1 above 50 years of age. Of the cases with equivocal atypia, 72 (50%) proved to be ALT/WDL. Those in the retroperitoneum/abdomen/pelvis were ALT/WDL in 30 cases (35%), and those that had recurred were ALT in 18 cases (55%). Recurrence, atypia, and having multiple indications for testing were more common in ALT than in benign lesions (P=0.02, 0.0001, 0.0012, respectively). No ALT/WDL occurred in the hands and feet, and only a single ALT/WDL was superficial (1 ALT/WDL vs. 60 @entity362 /spindle cell or @entity362 ). Small (<10 cm) @entity5 without additional features were always benign (n=9). On the basis of our results, FISH testing is recommended for: (1) recurrent lesions; (2) @entity75 that are >10 cm in @entity1 over 50 years of age; (3) in cases with equivocal atypia; (4) in lesions of the retroperitoneum/pelvis/abdomen, and in special clinical situations as directed by treating clinicians. Testing is low yield in superficial lesions, in small extremity lesions without additional indicators for testing, in large extremity lesions without additional features in @entity1 under the age of 50, and in lesions arising in the hands/feet. More evidence is needed regarding testing in @entity75 without additional features. By adopting these criteria, we could have avoided testing 74 cases, missing a single superficial ALT/WDL.
