Immunohistochemical assessment of vimentin expression and Ki-67 proliferation index in conventional urothelial carcinoma: a study of 60 Egyptian patients.

BACKGROUND

Urothelial carcinoma is a common malignancy with a substantial burden, including in Egypt. Although Ki-67 and EMT-related markers such as vimentin have been previously studied, region-specific validation and practical cutoff performance remain relevant.Author names: Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Also, kindly confirm the details in the metadata are correct. We have made the requested corrections. In addition, we would like to change the author order so that Deema Abu Al-Teen is listed as author number 4, and Abdulhadi Samman is moved to author number 8 in her place, with the same affiliation as currently shown related to each author, Samman (Jeddah) and Abu Al-Teen (Amman).

METHODS

This cross-sectional study included 60 archival conventional UC cases diagnosed at university hospitals during 2024. Tumors were re-reviewed to confirm grade and stage and categorized as NMIBC or MIBC. Immunohistochemistry was performed for vimentin and Ki-67 (MIB-1). Vimentin was considered positive when ≥ 10% of tumor cells showed convincing cytoplasmic staining. The Ki-67 labeling index was assessed in hotspots by counting ≥ 500 tumor nuclei and categorized as low (< 30%) versus high (≥ 30%) using a predefined pragmatic cutoff. Multivariable logistic regression was used to identify independent predictors of high-grade disease.

RESULTS

Vimentin positivity was detected in 18/60 cases (30.0%), and high Ki-67 index was present in 37/60 (61.7%). High Ki-67 independently predicted high-grade carcinoma (OR = 5.601, p = 0.009) and was significantly associated with high grade (p = 0.011), non-papillary pattern (p < 0.001), and muscle invasion (p = 0.001), but not lymphovascular invasion (p = 0.405). Vimentin showed no significant associations and was not an independent predictor; Ki-67 and vimentin were not significantly correlated.

CONCLUSION

In this Egyptian cohort, Ki-67 ≥ 30% was strongly associated with adverse pathological features and independently predicted high-grade disease, supporting its use as a practical ancillary marker and providing regional validation of prior reports. Vimentin was not significantly associated with the studied parameters in this dataset. Future studies should assess alternative cutoffs within the same cohort and validate outcome-linked thresholds in longitudinal datasets.