Determining the Role of Immunohistochemical Expression of CK20 in Grading Urothelial Carcinoma

Background: The cytoskeleton-associated intermediate filaments, CK20 belong to epithelial subgroups and it has a controlled expression in gastrointestinal marked cells and in the urinary tract. During embryogenesis, cytokeratin is the first intermediate filament type and they provide facilitation in maintaining the integrity and mechanical stability of cells. It is identified with regard to neoplastic urothelial cells there is a strong and diffuse cytoplasmic immunoreactivity for CK20 that involve all three layers of the urothelium. Therefore, the aim of the study was to determine the role of the immunohistochemical expression of CK20 in the grading of urothelial carcinoma.

Methodology: It was a retrospective cross-sectional study that was conducted at the Department of Histopathology, Lady Reading Hospital, Peshawar, Pathology department, Sheikh Zayed medical college and Hospital, Rahimyar Khan and Khyber Medical college and Khyber Teaching Hospital, Peshawar from March 2021 till September 2021. Ninety-seven, (97) Paraffin-embedded blocks of urothelial carcinoma along with records of these patients, which were collected over three years from January 2018 till December 2020, were retrieved from the archives of the Histopathology departments of these hospitals. These blocks were cut and stained with Hematoxylin Eosin and CK20 antibodies. Expression of CK20 was noted by two consultant pathologists. Positive expression was considered when cytoplasmic immunohistology expression of CK20 was seen in deep layers of the urothelium or diffused strong cytoplasmic staining of urothelial cells beyond the superficial cells was found. Negative expression was defined as CK 20 staining restricted to the superficial cells or Negative expression was defined as CK 20 staining restricted to superficial “Umbrella” cells of urothelium.

Results: Out of 97 patients, the minimum age was 20 years and maximum age was found to be 90 years with mean + standard deviation of 64 +11 years. There were 86 (88.6%) male patients and 11 (11.3) female patients. Low grade urothelial carcinoma was seen in 49(51 %) patients while 48 (49%) cases displayed high grade morphology. CK20 was found positive in 74 (76.3%) patients. Among positive cases, 43 cases were high grade and 31 cases were low grade urothelial carcinomas.

Conclusion: CK20 Positivity was seen in 76.3% of the patients with papillary urothelial carcinoma. CK20 is an important immunohistochemical marker for early diagnosis and grading of urothelial carcinomas. Positive Immunohistochemistry staining of the urothelial carcinomas were found in high-grade as well as low-grade urothelial carcinomas but in comparison, 43 cases of high-grade urothelial carcinomas had exhibited positive immunohistochemistry staining for CK 20 and 31 cases of low-grade urothelial carcinomas had exhibited positive staining for CK20 which would indicate that perhaps immunohistochemistry staining features of urothelial carcinoma would tend not to completely differentiate between high-grade and low-grade urothelial carcinomas.