Study of cytomorphology and immunohistochemistry on cell block for categorisation of primary lung tumours

Abstract

Introduction: Lung cancer is the most common cancer and is the leading cause of mortality worldwide. It accounts for 1-5 million deaths in the world and 2.5 million deaths in developing countries.1 Objectives 1. To study the morphology of primary lung tumours on fine needle aspiration samples. 2. Categorisation of lung tumours by cytomorphology and with immunohistochemistry on cell block wherever available. 2. To assess the diagnostic accuracy of FNAC of lung tumours Methodology: This study was a prospective study conducted on fine needle aspiration samples of 245 cases presenting as lung masses over a period of one year from march 2015 to February 2016. Results: The following observations were made on the sample size of 245 cases of lung tumours. The age of occurrence was between 32-88 years. Most common clinical presentation is cough with expectoration and haemoptysis. Most commonly the lesions were located in the right lung (61.2%). Adenocarcinoma was the most common tumour in our study, followed by squamous cell carcinoma, and neuroendocrine carcinoma. 2 cases of adenosquamous carcinoma, 2 cases of primary plasmacytoma and 1 case of Non-Hodgkin’s lymphoma were also noted. Out 245 cases,30 cases were unsatisfactory aspirate. Out of 215 satisfactory aspirate, IHC was available for 54 cases. IHC confirmed the diagnosis of adenocarcinoma in 30 cases, squamous cell carcinoma in 10 cases, neuroendocrine carcinoma in 11 cases and adenosquamous carcinoma in 2 cases, and 1 case of plasmacytoma lung. We had 2 cases with discordance between cytomorphology and IHC (2 cases which were diagnosed as neuroendocrine carcinoma on cytolomorphology, the IHC findings showed positivity for adenocarcinoma). Immunohistochemistry is helpful in subtyping non- small cell carcinoma, NOS and poorly differentiated carcinoma into adeno, squamous and neuroendocrine carcinomas. 2 cases of adenosquamous cell carcinoma were also confirmed by IHC. Conclusion: The diagnostic accuracy of Fine needle aspiration cytology for primary lung tumours in our study is 87.75%. The sensitivity is 96.4% and specificity 100% in the study. The high accuracy rate was obtained due to correlation with clinical, radiological and cytopathological findings.