OBJECTIVETo investigate the value of cytokeratin 20 (CK20) immunocytochemical (ICC) detection in the urine liquid-based cytological specimens in diagnosis of urothelial carcinoma (UC).

METHODSThe study consisted of prospective and retrospective groups. In the prospective group, voided urine samples were collected from patients with a variety of urological conditions and healthy individuals. Urine cytological diagnosis and CK20 ICC were performed on the collected specimens. In the retrospective group, archived urine slides with cytological diagnoses of atypical urothelial cells (AUC), suspicious carcinoma (SuCA) and carcinoma (CA) were selected. Then they were re-stained immunocytochemically with monoclonal antibody against CK20 after decolorization. Histological diagnosis and clinical follow-up result were used as the gold standard for analysis.

RESULTSThere were 136 cases in the prospective group, including 89 cases of UC, 19 cases of other urogenital malignancies, 12 cases of benign lesions and 16 cases of normal control. The sensitivity of CK20 ICC in detection of UC was 75.3%, significantly higher than that of LBC (48.3%, P < 0.001). The positive rate of CK20 was 64.7% (22/34) in G1 UC, 73.3% (22/30) in G2 UC, and 91.3% (21/23) in G3 UC (P < 0.001). The specificity of CK20 ICC was 91.5%, the same as that of LBC. There were 163 cases in retrospective group, including 119 cases of UC, 17 cases of other urogenital malignancies and 27 cases of benign lesions. The cytological diagnoses of them were 68 cases of CA, 47 cases of SuCA and 48 cases of AUC. The positive rates of CK20 ICC in UC and non-UC (other urogenital malignancies and benign lesions) cases were 90.8% and 15.9%, respectively, with a statistically very significant difference (P < 0.001). The LBC of all the 119 cases of UC included 62 (52.1%) cases of CA, 35 (29.4%) cases of SuCA and 22 (18.5%) cases of AUC. The positive rates of CK20 in the LBC-diagnosed CA, SuCA and AUC were 96.8%, 97.1% and 63.6%, respectively. The LBC of all the 44 non-UC cases included 6 (13.6%) cases of CA, 12 (27.3%) cases of SuCA and 26 (59.1%) cases of AUC, and the positive rates of CK20 in the LBC-diagnosed CA, SuCA and AUC were 33.3%, 33.3% and 3.8%, respectively. The differences of UC and non-UC cases between the corresponding categories of LBC were significant (P < 0.0001, respectively).

CONCLUSIONCK20 immunocytochemistry as an auxiliary method to urine liquid-based cytology can increase the sensitivity in detection of urothelial carcinomas.