Correct diagnosis of pulmonary tumors is essential for treatment decision and often relies on immunohistochemical markers. We stained tissue microarrays from resected primary lung cancer (n = 665) and pulmonary metastases (n = 425) for CK7, CK20, CDX2, CK5, p40, p63, TTF-1, napsin A, GATA3, and PAX8 to systematically assess the diagnostic value of these markers. Primary lung adenocarcinomas expressed TTF-1 in 90% and napsin A in 84% of the cases, whereas 10% were positive for p63, 7% for CDX2, 2% for CK20, and 2% for GATA3. Only 68% of the lung adenocarcinomas were positive for CK7, TTF-1, and napsin A and negative for all other markers. Primary lung squamous cell carcinomas expressed CK5, p40, and p63 in 94%-97% of cases, whereas 44% were positive for CK7, 20% for GATA3, 7% for CDX2, and 3% for TTF-1. Rare cases expressed PAX8, CK20, or napsin A. Pulmonary metastases of colorectal cancer were positive for CK20 in 83% and CDX2 in 99% of the cases. Rare cases expressed CK7, p63, or PAX8, whereas 4% expressed TTF-1. Pulmonary metastases of renal cell carcinomas were positive for PAX8 in 74%, napsin A in 7%, and CK7 in 7% of the cases. Pulmonary metastases of breast cancer were positive for GATA3 in 93% and CK7 in 78% of the cases, whereas 15% expressed CK5. Information on expression and patterns of immunohistochemical markers facilitates histopathological diagnostics. Evidently, unusual immune profiles occur and may lead to incorrect diagnosis.
Keywords: CDX2; Cytokeratin; GATA3; Napsin A; TTF-1; Tissue microarray.
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