Correlation of Immunohistochemical Staining Patterns of p53 with Mutational Analysis in Ovarian Carcinomas
A Yemelyanova, R Vang, IM Shih, RJ Kurman. Johns Hopkins Hospital, Baltimore, MD
Background: Immunohistochemical staining for p53 is used as a surrogate for mutational analysis in the diagnostic workup of ovarian carcinomas. Strong and diffuse immunostaining for p53 is generally interpreted as likely indicating a TP53 gene mutation. The goal of this study was to confirm this impression and also to determine whether the low-level or absent expression correlates with mutation or wild type TP53..
Design: Thirty cases of ovarian carcinoma (25 high grade serous ovarian/peritoneal carcinomas, 2 low-grade serous carcinomas, 2 clear cell carcinomas, and 1 well-differentiated endometrioid carcinoma) were studied. These cases were analyzed for TP53 mutation by nucleotide sequencing (exons 4-9) and also subjected to immunohistochemical analysis of p53 expression.
Immunohistochemical staining patterns and mutational analysis of p53 in ovarian carcinomas.All cases demonstrated weak to moderate staining intensity; All cases demonstrated strong to moderate staining intensity
|Staining Pattern (% positive cells)||Wild type||Nucleotide deletion||Nucleotide insertion||Nucleotide substitution||Nucleotide substitution with formation of Stop codon||Changes in intron region|
| 10% ||3||1||-||-||-||-|
|10 - 50%||3||-||-||-||-||-|
|51 - 74%||-||-||-||3||-||1|
|75 - 100%||-||1||-||10||1||-|
Conclusions: Complete absence of p53 expression is associated with a TP53 mutation and is not characteristic of wild type TP53. Tumors in which less than 50% of cells are positive almost always contain wild type TP53. Tumors in which more than 50% of cells are positive have a TP53 mutation.
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 137, Wednesday Morning