Abstract
BackgroundIt is important to discriminate between primary and secondary lung cancer. However, often, the discriminating diagnosis of primary lung acinar adenocarcinoma and lung metastasis of colorectal cancer based on morphological and pathological findings is difficult. The purpose of this study was to evaluate the clinical usefulness of immunohistochemistry of β-catenin, cytokeratin (CK) 7, and CK20 for the discriminating diagnosis of lung cancer.MethodsWe performed immunohistochemistry of β-catenin, CK7, and CK20 in 19 lung metastasis of colorectal cancer samples, 10 corresponding primary colorectal cancer samples and 11 primary lung acinar adenocarcinoma samples and compared the levels of accuracy of the discriminating diagnosis by using antibodies against these antigens.ResultsPositive staining of β-catenin was observed in all the lung metastasis of colorectal cancer samples as well as in the primary colorectal cancer samples but in none of the primary lung acinar adenocarcinoma samples. Positive staining of CK7 was observed in 90.9% of the primary lung acinar adenocarcinoma samples and in 5.3% of the lung metastasis of colorectal cancer samples, but in none of the primary colorectal cancer samples. Positive staining of CK20 was observed in all the primary colorectal cancer samples and in 84.2% of the lung metastasis of colorectal cancer samples, but in none of the primary lung acinar adenocarcinoma samples.ConclusionCombined immunohistochemistry of β-catenin, CK7, and CK20 is useful for making a discriminating diagnosis between lung metastasis of colorectal cancer and primary lung acinar adenocarcinoma. This method will enable accurate diagnosis of a lung tumor and will be useful for selecting appropriate therapeutic strategies, including chemotherapeutic agents and operation methods.
Highlights
It is important to discriminate between primary and secondary lung cancer
It is occasionally difficult to determine on the basis of clinical features whether the lung tumor is a primary lung cancer or a lung metastasis of colorectal cancer; this is because there are cases of lung metastasis at the early stages of colorectal cancer and those that occur more than 5 years after a colorectal cancer operation
Immunohistochemistry of β-catenin, CK7, and CK20 β-catenin staining was localized to the cell membrane and was absent from the cytoplasm and nucleus of normal colorectal epithelial cells, normal bronchial epithelial cells, bronchial gland cells, and alveolar cells
Summary
It is important to discriminate between primary and secondary lung cancer. often, the discriminating diagnosis of primary lung acinar adenocarcinoma and lung metastasis of colorectal cancer based on morphological and pathological findings is difficult. Recent studies have shown that alterations in the Wnt signaling pathway, including mutations in the adenomatous polyposis coli (APC), β-catenin and Axin genes, play important roles in the carcinogenesis of various malignant tumors [2]. Mutations in these genes result in accumulation of the β-catenin protein in the cytoplasm and the accumulated βcatenin translocates into the nucleus [3]. It is interesting to note that alterations in the Wnt signaling pathway exist in almost all cases of colorectal cancer and result in nuclear accumulation of the β-catenin protein [6,7,8]
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