Audit of Transthoracic Fine Needle Aspiration of the Lung: Cytological Subclassification of Bronchogenic Carcinomas and Diagnosis of Tuberculosis

KB Tan, TP Thamboo, SC Wang, Barbro Nilsson, A Rajwanshi, M Salto-Tellez
Correspondence: Dr Tan Kong Bing, pattankb@nus.edu.sg

ABSTRACT
Introduction Transthoracic fine-needle aspiration cytology (FNAC) is a useful tool for evaluating neoplastic and inflammatory lung nodules. In view of the relative paucity of published audit studies regionally, such a study was undertaken to assess the use of the technique in our centre.
Methods One hundred and fourteen FNACs were performed during 1997-1999. Immediate assessment for specimen adequacy was done. Diagnoses were correlated with clinical-pathological information and selective blind review performed.
Results Cytologically, 65.8% of cases were malignant, 1.8% were atypical, 25.4% were inflammatory/non-malignant and 7% were inadequate. Cytological-histological tumour diagnostic concordance was 94.4%. Diagnostic sensitivity for malignancy: 93.4%, specificity: 95.8%, accuracy: 94%. Eight inadequate/ benign cases (7%) proved to be malignant with clinical-pathological follow-up. Tuberculosis was confirmed (acid-fast bacilli detected) in six cases (5.3%) and suggested in a further 10 cases (8.8%). The cytological review showed 96% concordance with the original benign/malignant diagnoses. Pneumothorax rate was 18%.
Conclusion FNAC is an accurate and safe method for the evaluation of lung nodules and it enables subclassification of bronchogenic carcinomas in the vast majority of cases. It is also useful for the diagnosis of tuberculous pulmonary nodules. Immediate assessment optimises specimen adequacy; inadequate/non-malignant smears in particular, need clinical correlation, close follow-up and re-biopsy, if necessary.

Keywords: transthoracic FNAC, follow-up, cytology
Singapore Med J 2002; 43(11): 570-575