Cytologic difference between benignity and malignancy in suspicious cases employing urine cytodiagnosis using a liquid-based method.

Objective: To follow cases with atypical cells or suspicious cases on first examination by liquid-based cytology (LBC), comparing cases that became negative and those confirmed to be positive (urothelial carcinoma) with regard to the cell morphology.

Study Design: Urine cytology was performed employing LBC in 323 samples. Of 75 suspicious cases on first examination, 5 and 8 cases were identified with (positive) and without (negative) cancer on reexamination, respectively. Cell morphology was investigated in the first suspicious preparations of these cases.

Results: Fewer cells were present in the samples of negative cases, and atypia was generally weak. The nuclei were swollen and pale, and hyperchromatism was weak. In contrast, in positive cases, nuclear swelling, flattening, shrinkage, and pale staining were less marked compared with those in negative cases. The nuclei were hyperchromatic and irregular in many cases. Nuclear cannibalism, multinucleation, anisokaryosis, three-dimensionality, and an irregular arrangement were considered to be features strongly suggesting malignancy.

Conclusion: The efficiency of diagnosis employing the LBC is high because of the cell collection rate. It was shown that the accuracy of diagnoses made employing the LBC method can be increased by understanding the characteristics of the cell morphology in suspicious cases.