Immunocytochemistry Study on Pulmonary Cytology Samples in Lung Cancer

There is an increasing need to subtype non-small cell lung carcinoma (NSCLC) into squamous cell carcinoma and adenocarcinoma of lung, and this subtyping guides the treatment with the advent of targeted therapies that are available for cases of adenocarcinoma of lung, by which prognosis can be improved. In cases of lung cancer, many a times, cytology may be the only material available to render a diagnosis; cases that are poorly differentiated on morphology are challenging to subtype and the immunocytochemical markers can be applied on these cytosmears for further subtyping of NSCLC. Aims and Objectives This study was carried out to check the expression of p63 and TTF-1 in diagnostically difficult cases, such as NSCLC, poorly differentiated lung carcinomas on pulmonary cytology samples, and to further subtype them into squamous cell and adenocarcinoma. Materials and Methods The study period was from 1 September 2013 to 31 August 2015; during this span, the total number of malignancies that were diagnosed on cytology was 585 cases. Prestained slides (haematoxylin and eosin or H&E, Papanicolaou or Pap) were collected over a span of these two years and these were destained using 1% acid alcohol with intermittent washing followed by running of p63 and TTF-1 as the immunocytochemical markers. Observations and Results The smears that are positive for p63 are labelled as squamous cell carcinoma and those that are positive for TTF-1 are labelled as adenocarcinoma, as these markers are highly sensitive and specific for the diagnosis of squamous cell and adenocarcinoma, respectively; neuroendocrine markers were used in the cases that were positive for TTF-1 to rule out small cell carcinoma. Conclusion: By the positive expression of p63 and TTF-1, the cases were labelled as squamous cell carcinoma and primary adenocarcinoma of lung, with due considerations given to the clinical and radiological parameters.