Immunocytochemical Evaluation of TTF-1, Napsin-A, and p-63 for Subtyping of Non-Small Cell Lung Carcinoma and Clinicopathological Correlation.

Background: Carcinoma of lung is the most common cause of cancer-associated mortality worldwide. About 70% of lung cancer cases are unresectable and present in advanced stages. So, cytology and small core needle biopsy specimen are available for diagnostic as well as prognostication workup. Subtyping of non-small cell lung cancer (NSCLC) is essential for the treatment and further workup study. For this, immunocytochemistry (ICC) plays a crucial role that helps in early diagnosis. Subtyping of NSCLC from cytology samples using ICC markers like TTF-1, Napsin-A, and p63 and their clinicopathological correlation are the aims of the study.

Materials and methods: This ambispective study was conducted in the pathology department of a tertiary care hospital of eastern India for a 2-year period from 2018 to 2020. In our study, 46 cytologically diagnosed cases of NSCLC were included. Subtyping was done by cytomorphology and correlated with ICC expression, histopathology, and clinicopathological parameters.

Results: In our study, adenocarcinoma (ADC) was the most common (32.61%) cancer. Most cases of ADC showed positive expression of TTF-1 and Napsin-A, and p63 was positive in most cases of squamous cell carcinoma (SCC). Concordance with cytomorphology and ICC was 87.50% and 81.81% with ADC and SCC, respectively. Cyto-ICC-histo concordance was observed in 85.51% of ADC and 66.66% of SCC cases. Sensitivity was 100%, 93.1%, and 100% for TTF-1, Napsin-A, and p63, respectively. Specificity of both TTF-1 and Napsin-A was 88.2% and for p63 was 93.8%.

Conclusion: In small biopsy along with cytology samples, ICC is cost-effective and plays an important role in early diagnosis along with management of NSCLC.