Utility of thyroid transcription factor-1 and CDX-2 in determining the primary site of metastatic adenocarcinomas in serous effusions.

OBJECTIVE

To evaluate the usefulness of thyroid transcription factor-1 (TTF-1) and CDX-2 in determining the primary tumor site of metastatic adenocarcinomas (ACs) in serous effusions.

STUDY DESIGN

Cell blocks were constructed from cells in metastatic AC effusion fluids (n = 97) that had been previously stained with a panel of antibodies against MOC-31, D2-40 and calretinin. Primary tumor sites included the lungs (n = 52), ovaries (n = 6), pancreas (n = 4), breasts (n = 3), bile duct (n = 2) and gastrointestinal (GI) tract (30), including stomach (n = 28) and colon (n = 2). Primary sites were determined by tissue confirmation of the original tumor or review of the clinical charts. Immunocytochemical staining was performed with antibodies against TTF-1 and CDX-2.

RESULTS

The lung ACs showed TTF-1 positivity in 58% (30/52) of cases. All nonpulmonary ACs lacked TTF-1 staining. Among the 30 GI ACs, 9 (30%) (7 from the stomach and 2 from the colon) showed CDX-2 positivity. All non-GI ACs lacked CDX-2 staining. Specificities and positive predictive values for TTF-1 and CDX-2 equaled 100% for metastatic pulmonary and GI ACs, respectively.

CONCLUSION

Our results suggested that TTF-1 and CDX-2 are specific markers to separate metastatic pulmonary and GI ACs, respectively, from other metastatic ACs in serous effusions. However, sensitivity values of these markers were low.