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K-RAS, B-RAF and GNAS Gene Status and Immunohistochemistry Analysis of Mucinous Neoplasm of Appendix
xinyu ren
Departments of Pathology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
Corresponding Author
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AIM
Low grade appendiceal mucinous neoplasm (LAMN) and serrated lesions are sometimes hard to differentiate from morphology. We try to characterize them from the immunohistochemical and molecular perspective and to reflect the difference between them.
METHODS
25 appendix neoplasm including 13 LAMNs, 12 serrated lesions were selected from January 2013 to December 2014. Immunohistochemical analyses for cytokeratin 20, MUC6, MUC5AC, MUC1, Ki-67, P53 and mismatch repair (MMR) proteins including MLH1, PMS-2, MSH-6, MSH-2 were performed. Microsatellite instability (MSI) status was also evaluated. Besides, we detect K-RAS, B-RAF and GNAS gene mutation status of these lesions.
RESULTS
Immunochemically, 83.3% serrated lesions showed scattered CK20 staining in the deep crypt, which was less so for LAMNs. As for mucin expression, MUC5AC had slightly higher positive rate in LAMNs and than in serrated lesions.MUC1 was significantly higher expressed in LAMNs than in serrated lesions. 46.1% LAMNs have P53 expression in deep crypt, while P53 was negative in the deep crypt of serrated lesions. 58.3% serrated lesions had deficient MMR protein expresion pattern compared to 23.1% of LAMNs. B-RAF mutation was detected in 3 cases, all were serrated lesions. K-ras and GNAS mutation was detected in both LAMNs and serrated lesions.
CONCLUSION
Immunohistochemical panel comprising markers such as CK20, MUC5AC, MUC1, Ki-67 and P53, with genotyping covering hotspots of the KRAS, BRAF and GNAS genes can help the differential diagnosis of low grade appendix neoplasm.
Keywords
low grade appendiceal mucinous neoplasm, serrated lesions, MUC5AC, MUC1, MUC6, K-ras, b-raf, GNAS
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Supporting information Additional supporting information may be found in the online version of this article: Table S1 Antibodies and optimizations for the immunohistochemical analysis. Table S2 Coverage of kits of BRAF and KRAS by Sanger sequencing.
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Research
K-RAS, B-RAF and GNAS Gene Status and Immunohistochemistry Analysis of Mucinous Neoplasm of Appendix
xinyu ren
Departments of Pathology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 14 Aug, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Pathology
License:
This work is licensed under a CC BY 4.0 License. Read Full License
AIM
Low grade appendiceal mucinous neoplasm (LAMN) and serrated lesions are sometimes hard to differentiate from morphology. We try to characterize them from the immunohistochemical and molecular perspective and to reflect the difference between them.
METHODS
25 appendix neoplasm including 13 LAMNs, 12 serrated lesions were selected from January 2013 to December 2014. Immunohistochemical analyses for cytokeratin 20, MUC6, MUC5AC, MUC1, Ki-67, P53 and mismatch repair (MMR) proteins including MLH1, PMS-2, MSH-6, MSH-2 were performed. Microsatellite instability (MSI) status was also evaluated. Besides, we detect K-RAS, B-RAF and GNAS gene mutation status of these lesions.
RESULTS
Immunochemically, 83.3% serrated lesions showed scattered CK20 staining in the deep crypt, which was less so for LAMNs. As for mucin expression, MUC5AC had slightly higher positive rate in LAMNs and than in serrated lesions.MUC1 was significantly higher expressed in LAMNs than in serrated lesions. 46.1% LAMNs have P53 expression in deep crypt, while P53 was negative in the deep crypt of serrated lesions. 58.3% serrated lesions had deficient MMR protein expresion pattern compared to 23.1% of LAMNs. B-RAF mutation was detected in 3 cases, all were serrated lesions. K-ras and GNAS mutation was detected in both LAMNs and serrated lesions.
CONCLUSION
Immunohistochemical panel comprising markers such as CK20, MUC5AC, MUC1, Ki-67 and P53, with genotyping covering hotspots of the KRAS, BRAF and GNAS genes can help the differential diagnosis of low grade appendix neoplasm.
Figure 1
Figure 2