Prevalence of tuberculosis in small pulmonary nodules obtained by video-assisted thoracoscopic surgery

The prevalence of tuberculosis in small solitary lesions of the lung obtained by video-assisted thoracoscopic surgery (VATS) is still unclear. Of 103 lung lesions resected by VATS in 98 patients (47 men, 51 women), 19 were identified macroscopically as inflammatory changes, 78 were neoplastic, and 6 were undefined. Presumptive diagnosis based on microscopic analysis of fresh specimen smears treated with Papanicolaou stain was performed in 19 lesions. Of these, 11 lesions had epithelioid cells, granulomas with caseous necrosis and Langerhans-type giant cells. The 6 undefined lesions were non-inflammatory benign changes. Isolation and identification of tuberculosis were based on microscopic findings of fresh material smears and sections of fixed specimens stained with Ziehl-Neelsen's dye, cultivation using egg-based Ogawa medium, and in situ hybridization between polymerase chain reaction (PCR) products of each of the 11 lesions and specific DNA sequences for Mycobacterium tuberculosis, M. avium, and M. intracellulare. Of these 11 lesions, M. tuberculosis was confirmed in one (0.96%) by PCR and M. avium was confirmed in four by culture and PCR. Of the 78 malignant lesions, final pathologies were primary lung cancer (n=59, 70.2%) and pulmonary metastatic cancer (n=19, 22.6%). The most frequent primary malignant cancer was adenocarcinoma, which was found in 19 men and 28 women in the present study. Eight lesions in 8 men were squamous cell carcinomas. The results of the present study suggested that even though the prevalence of lung tuberculosis is low, attention should be paid to the presence of M. tuberculosis in specimens obtained by VATS.