Immunohistochemical Approach to Adenocarcinoma Metastatic to the Brain

• Published in: The FASEB journal 2007-04, Vol.21 (5), p.A390-A390
• Main Authors: Rojiani, Amyn M, Khoor, Andras, Strickland‐Marmol, Leah B
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.5.A390-d

Metastases to the brain may be the first presentation of systemic malignancy in 3–10% of new patients and thus pose a diagnostic challenge. While lung is the most common source, other frequent sites of origin include the GI tract and breast. The histologic appearance of metastatic adenocarcinoma often does not lend itself to identification of the primary source. In many cases immunohistochemical studies (IHC) to define these lesions may provide a reliable result, thus limiting the time and expense incurred by various clinical investigations. We have examined the IHC expression of cytokeratins 7 and 20, thyroid transcription factor ‐1 (TTF‐1) and the relatively new tissue specific transcription factor CDX2 in metastatic adenocarcinomas to the brain. 38 consecutive cases of metastatic adenocarcinoma (22 pulmonary, 10 breast, 6 gastrointestinal (2 esophagus/GE junction, 4 colorectal) to the brain were retrieved through a search of the surgical pathology files of the H. Lee Moffitt Cancer Center, Tampa, Florida. Confirmation of the primary site was obtained by chart review and histologic evaluation. Sections were immunohistochemically reacted with antibodies to TTF‐1, CDX2, and Cytokeratins 7 and 20 (CK7 and CK20) by standard methods. Specificities and positive predictive values for CDX2 and TTF‐1 equaled 100% for metastatic gastrointestinal and pulmonary adenocarcinomas, respectively. The negative predictive value of CDX2 was also very high at 97%. Our studies confirm that in conjunction with TTF‐1, CK7 and CK20, CDX2 can accurately differentiate the most common sources of metastatic adenocarcinoma from an unknown primary site to the brain.