Fluorescence in situ hybridization patterns in newly diagnosed superficial bladder lesions and corresponding bladder washings.

A multiprobe interphase fluorescence in situ hybridization (I-FISH) approach has become a useful ancillary tool in the follow-up protocol for patients with low-grade superficial bladder tumors. Nevertheless, reports contextually comparing I-FISH patterns in primary superficial tumor cells with those in concomitant washing cells at the time of initial tumor appearance are sparse. We comparatively evaluated I-FISH patterns of chromosomes 3, 7, 9, and 17 and of the CDKN2A and TP53 loci in newly diagnosed superficial bladder lesions and in corresponding bladder washings, to verify representatives of the latter type of sampling and to improve the efficacy of I-FISH follow-up. A total of 21 biopsies and 12 washings were examined. Samples obtained at the time of the tumor's first appearance showed the presence of cytogenetically abnormal clones in 80% of washings and 70% of biopsies. Five cases showed overlapping washing and biopsy I-FISH patterns; in three cases (and to a lesser extent in two others), consistent discrepancies between the two patterns was observed. The results indicate that knowledge of I-FISH patterns in both washing and biopsy cells on first tumor appearance may be of help in interpreting further follow-up I-FISH patterns, and that these should be considered in the context of the patient's entire clinical history.