The value of immunohistochemical markers in the differential diagnosis of adenocarcinomas

When differential diagnosis of adenocarcinoma in lung cannot be made, immunohistochemical staining may be necessary. Value of immunohistochemical staining in the differential diagnosis of adenocarcinomas was evaluated. 74 cases of different adenocarcinomas were enrolled. Pathology slides were stained with routine H&E staining and immunohistochemical markers. Positive CK7 immunostaining was seen in 100% of lung adenocarcinomas, papillary thyroid adenocarcinomas (PTC) and breast invasive ductal carcinomas (BIDC) and 15% of gastrointestinal (GI) adenocarcinomas, whereas none of prostate adenocarcinomas were positive. Positive CK20 immunostaining was seen in 75% of GI carcinomas and 10% of prostate adenocarcinomas whereas none of lung adenocarcinomas, BIDCs and PTCs showed positive CK20 immunostaining. TTF-1 staining was observed in 100% of PTCs, 83.3% of lung adenocarcinomas, 20% of BIDCs, 15% of GI carcinomas and 10% of prostate carcinomas. Positive p53 immunostaining was seen in 87.5% of lung adenocarcinomas, 85% of GI adenocarcinomas, 90% of PTCs and 80% of BIDCs. P53 staining wasn9t observed in prostate adenocarcinomas. CK7+CK20- staining panel9s sensitivity and specificity was found as 100% and 90% respectively in differential diagnosis of lung and GI adenocarcinoma. In differential diagnosis of lung adenocarcinomas from breast adenocarcinomas, TTF-1 marker had 83.3% sensitivity and 80% specificity. Consequently, immunohistochemical studies were found valuable in differential diagnosis of lung adenocarcinomas from other adenocarcinomas. Especially in patients with lung adenocarcinoma CK 7+CK20- staining pattern seem to give important contribution to differential diagnosis.