Figure 1. Unstained urine wet mount, 500× magnification, bar = 10 µm. A large, dense aggregate of epithelial cells is pictured. Observation of a large number of epithelial cells, especially in aggregates or sheets in urine, is abnormal. To better evaluate cell morphology and identify features of atypia, a dry mount cytologic preparation is very helpful.
Atypical epithelial cells may have larger-than-normal nuclei, coarsely clumped chromatin, large and prominent nucleoli, variable size and shape of nuclei and cells, multiple nuclei per cell, increased mitosis, and other features. Cellular atypia is not only seen with neoplasia but can also be seen with hyperplasia associated with inflammation, infection, or in response to mechanical trauma.
When atypical epithelial cells are observed in a urine sediment wet-mount preparation, it is helpful in many cases to prepare a dry-mount urine cytologic specimen for further evaluation, as thorough assessment of cell morphology is often not possible using low magnification and a wet-mount preparation. A dry-mount urine sediment cytologic specimen can also be easily shipped to a commercial laboratory for evaluation by a pathologist as needed.
In the following cases, atypical transitional epithelial cells or aggregates of epithelial cells were identified in the wet-mount urine sediment preparation, and additional cytologic preparations were pursued. In two of the cases, urine sediment dry-mount preparations were made. For the other two cases, additional techniques were used to collect a representative sample.
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Examination of exfoliative cytology obtained by urinary catheterization or fine-needle aspirate are relatively noninvasive and inexpensive methods for obtaining specimens from the urethra or urinary bladder mucosa.1-3 There is a low risk for seeding neoplastic cells into the peritoneum or body wall with fine-needle aspiration (FNA), but some recommend the use of urinary catheterization to avoid this complication,4 especially in patients with an operable bladder mass.