Voided urine cytology continues to play a paramount role in the surveillance of transitional cell neoplasms and as a screening modality in certain high-risk situations. Although a significant number of samples are diagnosed as atypical, there is little known about the outcome of these patients. In addition, the significance of transitional cell fragments in voided urine samples is uncertain. The objective of the current study was to evaluate retrospectively a large series of voided urine specimens that were reported as atypical. Standard cytomorphologic parameters were used with the aim of refining the atypical category.
The authors studied 201 consecutive voided urine samples from 1995 that were evaluated by liquid-based cytology for the following features: specimen cellularity, the presence and number of cell clusters, and the architecture of the cell fragments. In addition, cells were examined for the following cytologic features: high nuclear-to-cytoplasmic ratios, nuclear membrane irregularities, hyperchromasia, India-ink nuclei, and chromatin pattern. Cytoplasmic features were evaluated but were limited significantly by poor preservation. Only specimens with a biopsy or cystoscopy and/or from patients who were followed for > 5 years were analyzed further.
In total, 23.4% of specimens showed transitional cell carcinoma (TCC) on biopsy, including 20 Grade 1 TCCs and 21 Grade 2 TCCs. Specimen cellularity, cluster numbers, nuclear membrane abnormalities, hyperchromasia, and India-ink nuclei were associated significantly with TCC. Twenty-six specimens (18.9%) were associated with renal calculi.
The atypical category contained a significant proportion of low-grade TCCs. Transitional cell clusters in voided urine are relevant clinically. The clinical picture, including the previous history of TCC and the presence of urinary calculi, provides valuable information when evaluating voided urine cytology. These features and careful attention to India-ink nuclei and nuclear membrane abnormalities could help make the "atypical" category a more meaningful group.