The Spectrum of Polyoma Virus and Polyoma Virus-Like Changes in Urine Cytology: When Should an Atypical Diagnosis Be...

While the Paris system for reporting urinary cytology states that cells with well-recognized and typical changes of polyoma virus (PV) infection should not lead to a diagnosis of 'atypia, the prognostic significance of PV-like features is unknown.

Included were 284 urine cytology cases with PV or PV-like changes. Four cell types were identified. Cell A was typical of PV infection, cell B had a spider-web chromatin pattern, and cells C and D were degenerated cells with clumpy chromatin or homogeneous severely hyperchromatic nuclei, respectively. Events were correlated with a subsequent histological diagnosis of high-grade urothelial carcinoma (HGUC).

47% of cases had more than one cell type. The most common cell was D (64%) and the least common was A (27%). The most common cell to be present in isolation was D (n = 109, 60%). 92% of cases with cell A had other cell types. Overall, the presence of cell A was associated with a benign follow-up (1.2% association with HGUC). There was a gradual increase in the association with a HGUC diagnosis in cases with cells B (PPV = 8%), C (PPV = 15.5%), and D (PPV = 44%). The presence of only cells B, C, or D was predictive of HGUC in 22.4%, 33.3%, and 61.5%, respectively.

Cases with cell type A can be confidently diagnosed as 'negative for HGUC', even in the presence of associated cells with PV-like changes. Cases with cells displaying PV-like features (cell type B, C, or D) in the absence of type A features may represent degenerated HGUC cells.