Polyomavirus Remains a Diagnostic Pitfall in Urinary Tract Cytology
MA Havens, RJ Cabay, EM Wojcik, S Mehrotra, GA Barkan. Loyola University Medical Center, Maywood, IL
Background: Cells showing polyoma virocytopathic changes and high-grade urothelial carcinoma cells may closely mimic one another, to the point of being virtually indistinguishable. This presents a diagnostic dilemma, as these diagnoses have markedly different implications. Our study retrospectively evaluates our efficacy in distinguishing polyomavirus infection from urothelial carcinoma, and attempts to characterize their respective cytomorphologies.
Design: A departmental database search was conducted to identify patients with urine cytology specimens given a diagnosis of polyomavirus infection between January 2005 and July 2008. Of these cases, those that were either subsequently or previously diagnosed with urothelial carcinoma were included in our study. A separate search for patients diagnosed cytologically with polyomavirus who had at least two years of negative follow-up was conducted to establish a control group. The slides of these specimens were reviewed by two board certified pathologists, and widely-published features of polyomavirus infection and urothielial carcinoma were semiquantitatively analyzed.
Results: Our search identified fourteen lower urinary tract cytology specimens with features previously reported as polyomavirus from patients in our study group. Ten additional patients diagnosed with polyomavirus, without any history of carcinoma, were included in the control group. The slides from these cases were reviewed while blinded to the previous diagnoses. The differences between the two groups were not statistically significant for any of the major attributes, with the exception of nuclear membrane irregularity. More traditional identifying features of polyomavirus, such as the presence of nuclear inclusions, comet cell morphology, nuclear membrane thickening, and lace-like chromatin pattern, showed no statistical differences between the two groups.
Conclusions: We found statistically significant overlap in the morphologies of polyomavirus and urothelial carcinoma. Most notably, the glassy nuclear inclusions seen with polyoma appear to be much less specific than is generally appreciated. However, the presence of nuclear irregularity showed statistically significant predictive value. In many cases, the cytomorphologies of polyoma virus infection and urothelial carcinoma have enough common characteristics that even rigorous use of published morphologic criteria may be insufficient to reliably distinguish between the two.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 68, Wednesday Afternoon