The Expression of Cytokeratin 19 in Breast Carcinoma and Its Association with Hormone Receptor Status
Nathan A Aardsma, John V Groth, Sanjiv V Prabhu, Elizabeth L Wiley. University of Illinois Hospital & Health Sciences System, Chicago, IL
Background: Cytokeratin 19 (CK19) is the lowest molecular weight cytokeratin and is commonly used to mark pancreaticobilliary carcinoma in the liver and papillary carcinoma of the thyroid. CK19 has been shown to be expressed in normal breast tissue and breast carcinoma. CK19 mRNA is also used to detect circulating tumor cells and micro-metastases of breast carcinoma. CK19 expression and its relationship to breast predictive markers (BPM) has yet to be elucidated. The purpose of this study is to identify a relationship, if any, to BPM and other prognostic factors.
Design: Tissue microarrays of 125 cases of varying grades of breast carcinoma had been developed for quality assurance purposes and stained for Estrogen Receptor (ER), Progesterone Receptor (PR), and HER2/neu and scored using techniques prescribed by CAP and ASCO. CK 19 staining was performed and considered positive if any cytoplasmic or membranous stainging was present. Hormone expression was used to classify each tumor into the following subtypes: ER positive/HER2-neu negative (ER+), HER2-neu positive (HER2+) and triple negative (TN). Each subtype was compared to tumor expression of CK19 and reported as a percentage. Prognostic factors such as tumor size, tumor grade, and lymph node status were also compared to CK19 staining. Chi square analysis was performed to identify any significant findings.
Results: Overall expression of CK19 in breast carcinoma was 87.2%. A significant difference was seen when comparing TN to the other subtypes: 98% of (ER+), 88% of (HER2+), and 73% of (TN) expressed CK19 (χ 2 =14.34, p<0.0007). With regard to tumor grade, 100% of Grade 1, 94% of Grade 2, and 84% of Grade 3 carcinomas express CK19; however, this difference was not significant. An association between tumor size and lymph node status when compared to CK19 expression was not identified.
Conclusions: Cytokeratin 19 is expressed diffusely in breast carcinoma. Our data suggests CK19 expression does not correlate with tumor grade, tumor size, and lymph node status. However, we found a significant number of triple negative breast carcinoma lack CK19 expression. Thus independent use of CK19 may lack sensitivity in detecting metastatic breast carcinoma, specifically in those tumors that lack ER and HER2-neu receptor expression.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 12, Monday Morning