[Use of thyroid transcription factor-1, surfacfant protein-B, cytokeratin 7 and cytokeratin 20 in discrimination between primary and metastatic adenocarcinoma of lung].

OBJECTIVE

To evaluate the utility of thyroid transcription factor-1 (TTF-1), surfactant protein-B, (SP-B) cytokeratin 7 (CK7) and CK20 immunostaining in the discrimination between primary adenocarcinomas and metastatic adenocarcinomas.

METHODS

Formalin fixed, paraffin embedded tissue blocks from 42 primary lung adenocarcinomas and 30 metastatic carcinomas resected during operation were immunostained with monoclonal antibodies to TTF-1, SP-B, CK7, and CK20.

RESULTS

Positive immunostaining with TTF-1 and SP-B was noted in 74% and 52% of primary lung tumor, respectively. The positive immunostaining and specificity of such a combination for discriminating between primary and metastatic adenocarcinoma were 79% and 94%, respectively. All primary lung adenocarcinomas were CK7 positive, 24 (57%) were CK7 positive/CK20 negative and 18 were CK7 positive/CK20 positive in immunophenotype. Colon and breast were the most common sites of metastasis. All metastatic colorectal adenocarcinomas were CK20 positive, 11 (92%) were CK7 negative/CK20 positive and 1 was CK7 positive/CK20 positive in immunophenotype. The results of cytokeratin immunostaining in the metastatic breast tubular carcinomas were similar to those in the primary lung adenocarcinomas: 4 were CK7 positive/CK20 negative and 4 were CK7 positive/CK20 positive. CK7 positive, and TTF-1 or SP-B positive immunophenotype was seen in 33 (79%) primary lung tumors. A combination of CK7 negative, CK20 positive, and TTF-1 and SP-B negative was highly significantly associated with metastatic colorectal carcinomas compared with either primary lung adenocarcinomas or metastatic breast carcinomas (both P < 0.001). A combination of CK7 positive, CK20 negative, and TTF-1 and SP-B negative was highly significantly associated with metastatic breast carcinomas compared with either primary lung adenocarcinomas or metastatic colorectal carcinomas (both P < 0.001).

CONCLUSION

Use of a panel of antibodies including TTF-1, SP-B, CK7 and CK20 is helpful in discriminating between primary and metastatic adenocarcinomas of the lung and suggesting the primary sites of some metastatic adenocarcinomas.