Immunohistochemistry In the Diagnosis and Typing of Lung Carcinomas

To study the clinical and radiological presentation of lung cancer and diagnose the type of lung cancers using cytohistopathology and immunohistochemistry where-ever required. The study was carried out on 200 patients of lung cancer. Cytological investigations included sputum cytology, pleural fluid examination, percutaneous needle aspiration, trans-bronchial needle aspiration and FNAC lymph-node. Histopathology of paraffin embedded sections of lung biopsies was done. Immunohistochemical staining was done where ever required. Out of 200 cases, cytology was helpful in typing malignancy in 165 cases (82.5%).In the remaining 35 cases, 21 cases (10.5%) were suggestive of malignancy and 14 cases (7.0%) were inconclusive. On histological evaluation of 64 cases, typing was possible in 48 cases (71.8%) and 18 cases (28%) were reported as poorly differentiated carcinoma. After applying immunohistochemistry in 18 cases of poorly differentiated malignancies, 13 cases(72.2%) were positive only for CK5/6 as squamous cell carcinoma, 4 cases were positive for TTF1, out of which 3 were positive for CK7 making it as 4 cases(22.2%) of adenocarcinoma. One case (5.5% was positive for CK5/6, CK7 and TTF1 and was diagnosed as adeno-squamous carcinoma. Combination of various cytological techniques following additional use of histological evaluation of lung biopsies where ever required has raised the sensitivity of diagnosing lung cancer from 82.5% to 91.0% and immunohistochemistry clinched the diagnosis in poorly differentiated lung cancers.