Diagnostic terminology for urinary cytology reports including the new subcategories 'atypical urothelial cells of undetermined significance' (AUC-US) and 'cannot exclude high grade' (AUC-H)

Objective We studied whether atypical, non‐superficial urothelial cells (AUC) could be separated into new subcategories including AUC ‘of undetermined significance’ (AUC‐US) and ‘cannot exclude high grade’’ (AUC‐H) in order to help to standardize urine cytopathology reports, as it is widely accepted in the Bethesda system for gynaecological cytopathology. Methods We investigated whether AUC‐US and AUC‐H, defined by distinctive cytological criteria, might be separated with statistical significance according to actual diagnosis and follow‐up data. A series of 534 cyto‐histological comparisons taken in 139 patients, including 221 AUC at various steps of their clinical history was studied. There were 513 (96.1%) postcystoscopy and 469 (87.8%) ThinPrep® liquid‐based specimens (95.9% and 89.1% of AUC cases, respectively). Patients viewed between 1999 and 2011 had histological control in a 0‐ to 6‐months delay and were followed‐up during an additional 5.9 ± 9.2 (0‐ to 56‐) months period. Results The 221 AUC represented 0.8–2% of the specimens viewed during the study period. Among AUC‐H cases, 70 out of 185 (37.8%) matched with high‐grade lesions, compared with 3 of 38 (8.3%) of AUC‐US cases (P = 0.0003). Conservatively treated patients with AUC‐H more frequently developed high‐grade lesions than those with AUC‐US (54.1% versus 16.7%, P = 0.0007) with a 17.6‐months mean delay. Nuclear hyperchromasia, a nuclear to cytoplasm (N/C) ratio > 0.7 and the combination of both were the more informative diagnostic criteria, all with P