The Value of PAX-2 for the Work-Up of Metastatic Carcinoma of Unknown Primary: An Immunohistochemical Tissue Microarray Study of 694 Cases
TC Pereira, SM Share, AV Magalhaes, JF Silverman. Allegheny General Hospital, Pittsburgh, PA; Universidade de Brasilia, Brasilia
Background: PAX2 is a transcription factor that acts to regulate the expression of genes involved in mediating cell proliferation and growth, resistance to apoptosis, and cell migration. By employing tissue microarray technology, we evaluated the expression of Pax-2 in 694 carcinomas from various sites in order to determine its' utility in the work-up of metastatic carcinoma of unknown primary.
Design: IHC was performed for Pax-2 on paraffin embedded sections from tissue microarray of 694 cases of carcinomas from different organs. Cases were interpreted as positive if at least 5% of tumor cells had nuclear staining.
Results: The results of positive cases per primary site are listed as percentage of positive cases % (Number of positive cases/Total number): Lung 0% (0/113), renal cell carcinoma 65.38% (34/52), GI endocrine/neuroendocrine carcinoma 0% (0/20), stomach adenocarcinoma 0% (0/14), esophageal adenocarcinoma 0% (0/20), pancreas carcinoma 4.44% (2/45), prostate carcinoma 0% (0/38), urothelial carcinoma 2.82% (2/71), hepatocellular carcinoma 0% (0/12), cholangiocarcinoma 11.11% (1/9), colorectal carcinoma 0% (0/67), salivary gland carcinoma 6.67% (1/15), breast carcinoma 6.25% (5/80), thyroid carcinoma 8.89% (4/45), endometrium carcinoma 46.15% (18/39), cervix carcinoma 0% (0/11), ovary carcinoma 8.6% (8/43).
Conclusions: Pax-2 is mostly expressed in renal cell carcinoma (65.38%) and endometrial carcinoma (46.15%), with limited to absent expression in carcinomas of other primary sites. We believe that Pax-2 is a useful marker for the work-up of metastatic carcinoma of unknown primary site, especially if renal cell or endometrial carcinoma is considered in the differential diagnosis.
Monday, March 22, 2010 1:00 PM
Poster Session II # 247, Monday Afternoon