The utility of cytology in the diagnosis of adenocarcinoma lung: A tertiary care center study

INTRODUCTION: Pulmonary adenocarcinoma harbors various molecular abnormalities that include epidermal growth factor mutation, anaplastic lymphoma kinase gene re-arrangement, K-RAS mutations. The availability of targeted therapy against these molecular markers has revolutionized personalized medicine. Accurate cytological diagnosis of pulmonary adenocarcinoma will aid in utilising the cytology smears for molecular testing. OBJECTIVE: The objective of this retrospective study was to evaluate the diagnostic efficacy of various cytology samples in the diagnosis of pulmonary adenocarcinoma. MATERIALS AND METHODS: The study included a retrospective case series of 50 patients with biopsy proven non small cell lung carcinoma of adenocarcinoma subtype. The corresponding cytology reports of all the 50 cases were analyzed for different samples including broncho-alveolar lavage (BAL), bronchial washings, bronchial brush smears, pleural fluid, sputum and guided fine needle aspiration cytology (FNAC) of lung and metastatic lymph nodes. The overall cyto-diagnosis efficacy as well that of various cytological samples were analyzed. RESULTS: Multiple cytology samples were received in 14 of 50 cases. The overall diagnostic efficacy of the various cytology samples in the diagnosis of malignancy was 78% and 66.6% cases were accurately typed as non small cell lung carcinoma-adenocarcinoma. The best cytological sample for the detection of pulmonary adenocarcinoma was bronchial brush smears which had a detection rate of 70%. In fine needle aspiration cytology samples and bronchial washings the detection rate was 65.5% and 25% respectively. DISCUSSION AND CONCLUSION: In cases where the cytological diagnosis is certain the tissue biopsies can be simultaneously tested for EGRF and ALK gene mutations. Repeat biopsies are often required due to small amount of tumor tissue or necrotic biopsies. Alternate use of cytological specimen for molecular testing can be done when a diagnosis of pulmonary adenocarcinoma is established.