[1101] 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.
Results:
| Mutational analysis | ||||||
| Staining Pattern (% positive cells) | Wild type | Nucleotide deletion | Nucleotide insertion | Nucleotide substitution | Nucleotide substitution with formation of Stop codon | Changes in intron region |
| Negative | - | 3 | 1 | - | 2 | 1 |
 10%  | 3 | 1 | - | - | - | - |
| 10 - 50% | 3 | - | - | - | - | - |
| 51 - 74% | - | - | - | 3 | - | 1 |
75 - 100% | - | 1 | - | 10 | 1 | - |
| Total | 6 | 5 | 1 | 13 | 3 | 2 |
All cases demonstrated weak to moderate staining intensity; All cases demonstrated strong to moderate staining intensityConclusions: 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.
Category: Gynecologic
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 137, Wednesday Morning