Reply to Rana et al.

We have read with great interest the letter by Rana et al. who also have recently published on endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) of mediastinal lymphadenopathy due to tuberculosis. They focused on the echo features.

One of the main differences in both studies is the mean size of the tubercular lymph nodes when compared with those found with other etiologies. In their paper the mean size was not statistically different, while we found significant differences between tubercular and/or sarcoid lymphadenopathy and other nodes.

Very often reasons for the differences in size lie in the difference between the underlying diseases. In Europe, most of the mediastinal lymph nodes detected on EUS are “smoker’s nodes.” They are mainly small and located in the subcarinal space. In our series, 8/14 nodes that were not related to tuberculosis or sarcoidosis represented such nodes. A further 4 were due to cancer; such nodes can be very small, if detected an earlier stage, and this has been proven in a number of studies on EUS-FNA and lung cancer. In our study, patients with any suspicion of cancer were excluded, which implies that the malignant nodes were detected when the disease was in an early stage and the nodes seen were small. Rana et al. did not seem to have had such rigorous selection criteria, which then might have resulted in more advanced disease with increased nodal size. They also had a higher number with inflammatory disease in their patient population.

The mean (SD) sizes of the mediastinal tubercular nodes in our study were 20.4 (5.9) mm and were not larger in diameter when compared with those from other studies. Song et al. and Berzosa et al., respectively, reported mean diameters of 34 ± 14 mm and 28.6 mm; range 17.0 – 49.5 mm [1] [2]. However, we have also seen very small tubercular lesions of only a few millimeters, but in organs such as the pancreas or spleen [3].

Overall, the report of Rana et al. is not contradictory to the findings of our study.

They were not able to compare the size of nodes in tuberculosis and sarcoidosis, as there were only three sarcoid patients in their study. The reason why their nodes from “other diseases” were similar in size to those of tuberculosis might lie in the differences between the “other diseases” they found in their study, compared with those in our report.

This author strongly believes that EUS-FNA has much to offer for the diagnosis of tuberculosis, as shown by the number of publications on this topic in the past year or two. EUS-FNA can detect the disease but can especially help to find the much-feared resistant strains when cultures from FNA material are taken. In this respect, possible differences in the sizes of the nodes when found in the mediastinum might be much less important than the fact that an awareness of the “nearly forgotten disease” is raised, especially in Europe, and an innovative and highly reliable technique offered for the diagnosis when other means fail.

References

• 1 Song H J, Park Y S, Seo D W et al. Diagnosis of mediastinal tuberculosis by using EUS-guided needle sampling in a geographic region with an intermediate tuberculosis burden.  GIE. 2010;  71 1307-1313
• 2 Berzosa M, Tsukayama D T, Davies S F et al. Endoscopic ultrasound-guided fine-needle aspiration for the diagnosis of extra-pulmonary tuberculosis.  Int J Tuberc Lung Dis. 2010;  14 578-584
• 3 Fritscher-Ravens A, Mylonaki M, Pantes A et al. Endoscopic ultrasound-guided biopsy for the diagnosis of focal lesions of the spleen.  Am J Gastroenterol. 2003;  98 1022-1027