[1019] "Inconclusive" UroVysion Fluorescence In Situ Hybridization (FISH) Results: Follow-Up To Determine Clinical Implications of Diagnostic Terminology

DE Westfall, J Lopategui, M de Peralta-Venturina, S Bose, S Wang, DJ Luthringer, RS Parakh, MB Amin. Cedars-Sinai Medical Center, Los Angeles, CA

Background: FISH is more sensitive than the gold standard urine cytology in the diagnosis and monitoring of urothelial carcinoma. Currently, FISH is reported as either positive [defined as >4 cells with aneuploidy in at least 2 of the 3 chromosome (3, 7 or 17)enumeration probes (CEP) or loss of both copies of 9p21 in the locus specific probe (LSI) in >12 cells] or negative. Depending on the institution, cases with <4 aneuploid cells are reported as either "negative" or "inconclusive". At our institution we report these cases as "negative with less than four aneuploid cells". The clinical significance of these "inconclusive" FISH results remains to be determined.
Design: A total of 1731 urine specimens were analyzed by UroVysion FISH (Vysis, Downer's Grove, IL) using automated microscopic analysis of UroVysion slides (The DuetTM system, Bioview Inc, Billerica, MA) over a three-year period. Two-hundred one (12%) cases were positive, 1277 (77%) were negative and 160 (9%) had less than four abnormal cells ("inconclusive"). Follow up of the "inconclusive" cases, including urine cytology, repeat FISH testing or bladder biopsy performed within 12 months of the initial diagnosis of the "inconclusive" result was obtained from pathology reports.
Results: Of the 160 "inconclusive" cases, 77 (48%) had a follow up test and 83 (52%) had no follow up testing. Fifty-two (68%) cases were normal/benign/atypical on follow up testing. Twenty-five (32%) cases were found to have malignancy including 18 cases with subsequent positive FISH tests, 7 with malignant urine cytology specimens and 12 with a malignant diagnosis made on bladder biopsy. Most cases had follow up with a combination of cytology, FISH and/or surgical biopsy.
Conclusions: 1) Thirty-two percent of cases with an "inconclusive" FISH result and follow up testing were, in fact, malignant on subsequent testing. 2) Based on these results, an "inconclusive" FISH result of less than four abnormal cells, should not be reported as negative and may warrant closer clinical follow up than a purely negative result. 3) Fifty-two percent of patients with "inconclusive" FISH results were not followed up with subsequent testing. Thus our data indicates that it is essential to communicate to the treating urologist that a substantial subset of patients with "inconclusive" FISH results will have bladder neoplasia and require close clinical follow up.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 2:15 PM

Platform Session: Section A, Tuesday Afternoon

 

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