ROLE OF CYTOKERATINS (PANCK, CK5/6, CK7, CK20) AS AN IMMUNOHISTOCHEMISTRY MARKERS IN DIAGNOSIS OF EPITHELIAL MALIGNANCY (A STUDY OF 100 CASES)
Dr. Kreta Kansagara
, Dr. Dhara P. Trivedi , Dr. Preksha Mehta , Dr. Kinjal Buddheshbhai Nirmal
Cytokeratin, PanCK, CK7, CK20, CK5/6, immunohistochemistry, epithelial malignancy, carcinoma of unknown primary
Background:
Epithelial malignancies constitute the majority of human cancers and frequently pose diagnostic challenges, particularly in small biopsies, poorly differentiated neoplasms, and cases presenting as metastasis without a known primary site. Conventional morphology alone is often insufficient to determine epithelial lineage or predict the primary origin. Cytokeratins (CKs), a family of intermediate filament proteins expressed in epithelial cells, play a crucial diagnostic role owing to their characteristic and lineage-specific expression patterns. Pan-cytokeratin (PanCK) serves as a broad-spectrum epithelial marker, whereas CK7, CK20, and CK5/6 exhibit organ-specific and differentiation-specific profiles that help refine tumor classification. The CK7/CK20 immunophenotypic algorithm is especially valuable in metastatic adenocarcinomas and carcinoma of unknown primary (CUP).
Aim:
To evaluate the diagnostic utility and expression patterns of PanCK, CK7, CK20, and CK5/6 in 100 histologically confirmed epithelial malignancies and to assess their contribution in identifying tumor lineage and predicting the primary site, particularly in CUP and poorly differentiated tumors.
Materials and Methods:
A prospective–retrospective study was conducted on 100 epithelial malignancies diagnosed on routine H&E sections. Representative paraffin blocks underwent immunohistochemistry using primary antibodies PanCK, CK7, CK20, and CK5/6. Staining intensity, proportion of positive tumor cells, and distribution pattern were assessed. Clinical details, tumor site, and histologic subtype were correlated with CK expression. CK7/CK20 profiles were used to generate organ-specific diagnostic predictions. Special focus was placed on CUP cases to evaluate the effectiveness of CK profiles in suggesting probable primaries.
Results:
PanCK was positive in 98% of cases, confirming its high sensitivity for epithelial differentiation. CK7 was predominantly expressed in tumors of the lung, breast, ovary, endometrium, and pancreatobiliary tract, while CK20 expression was characteristic of colorectal adenocarcinoma, gastric intestinal-type carcinoma, and urothelial carcinoma. CK5/6 positivity was largely restricted to squamous cell carcinomas of the esophagus, cervix, and kidney, as well as mucoepidermoid carcinoma and a subset of urothelial carcinomas, highlighting its value in recognizing squamous or basal differentiation.
The CK7/CK20 immunoprofile provided significant diagnostic clues: CK7+/CK20− strongly suggested lung, breast, female genital tract, and pancreatobiliary primaries; CK7−/CK20+ was highly specific for colorectal carcinoma; CK7+/CK20+ supported urothelial and some upper GI origins; and CK7−/CK20− favored prostate and hepatocellular carcinoma. In CUP cases, cytokeratin profiling allowed identification of a probable primary in a majority of patients, with lung being the most common inferred site.
Conclusion:
Cytokeratin immunohistochemistry using PanCK, CK7, CK20, and CK5/6 is an indispensable component of the diagnostic armamentarium for epithelial malignancies. PanCK confirms epithelial lineage, while CK7 and CK20, especially in combined profiles, provide powerful organ-specific patterns. CK5/6 reliably identifies squamous and basal differentiation. CK-based immunoprofiling significantly enhances diagnostic accuracy in challenging cases, particularly CUP, and should be integrated into routine diagnostic algorithms to guide clinical management and targeted therapy.
"ROLE OF CYTOKERATINS (PANCK, CK5/6, CK7, CK20) AS AN IMMUNOHISTOCHEMISTRY MARKERS IN DIAGNOSIS OF EPITHELIAL MALIGNANCY (A STUDY OF 100 CASES)", IJSDR - International Journal of Scientific Development and Research (www.IJSDR.org), ISSN:2455-2631, Vol.11, Issue 1, page no.b150-b160, January-2026, Available :https://ijsdr.org/papers/IJSDR2601117.pdf
Volume 11
Issue 1,
January-2026
Pages : b150-b160
Paper Reg. ID: IJSDR_306957
Published Paper Id: IJSDR2601117
Downloads: 000816
Research Area: Science and Technology
Country: -, -, India
ISSN: 2455-2631 | IMPACT FACTOR: 9.15 Calculated By Google Scholar | ESTD YEAR: 2016
An International Scholarly Open Access Journal, Peer-Reviewed, Refereed Journal Impact Factor 9.15 Calculate by Google Scholar and Semantic Scholar | AI-Powered Research Tool, Multidisciplinary, Monthly, Multilanguage Journal Indexing in All Major Database & Metadata, Citation Generator
Publisher: IJSDR(IJ Publication) Janvi Wave
