, et al
On behalf of the Spanish Pediatric TB Research Network (pTBred) and the European NontuberculouS MycoBacterial Lymphadenitis in childrEn (ENSeMBLE) study. Interferon-gamma release assays differentiate between Mycobacterium avium complex and tuberculous lymphadenitis in children [published online ahead of print May 10, 2021]
J Pediatr
. doi.

Investigators from multiple institutions conducted a study to assess the utility of interferon-gamma release assays (IGRAs) to differentiate tuberculosis (TB) from Mycobacterium avium complex (MAC) as the etiology of subacute/chronic submandibular/cervical lymphadenitis in children. Patients <18 years old with TB lymphadenitis who were included in the Spanish Network for the Study of Pediatric TB (pTBred) database between 2013 and 2018 were eligible for the current study. pTBred is a collaborative network of healthcare professionals in Spain; a central database includes demographic, laboratory test, and clinical data on children with TB. Patients with lymphadenitis and TB (Mycobacterium tuberculosis [MTB] or Mycobacterium bovis) identified at any anatomic site by culture or PCR were included. Children <18 years old with lymph-adenitis caused by MAC, diagnosed by culture or PCR of samples obtained from the infected lymph node, who had been enrolled in the European Nontuberculous Lymphadenitis in Children Study (ENSeMBLE) between 1996 and 2018 also were included in the analyses. ENSeMBLE databases were reviewed, and demographic, laboratory and clinical data on patients were included in the current study abstracted.

Results of tuberculin skin tests (TSTs) and IGRAs, if performed, from study participants were collected. Additional information collected included age, site of lymphadenitis, and presence of pre-existing medical conditions. Differences between children with TB or MAC lymphadenitis were compared with t-tests or Mann-Whitney U tests for continuous variables or chi-square tests for categorical variables. The sensitivity and specificity of IGRAs to diagnose TB lymphadenitis were calculated.

Data were analyzed on 34 children with TB lymphadenitis (27 caused by MTB and 7 by Mycobacterium bovis) and 78 with MAC. Patients with TB lymphadenitis were significantly older than those with MAC (median ages 9.5 and 2.8 years, respectively; P <0.001) and more likely to have a pre-existing medical condition (6 children vs 0 with MAC; P = 0.002). Among those with MAC lymphadenitis, the site was submandibular/jugulodigastric in 64%; the most common site for those with TB was cervical (57%). IGRAs were positive in 1 of 32 (3.1%) children with MAC who were tested and in 21/23 (91.3%) of those with TB lymphadenitis (P <0.001). TSTs were positive in 59.5% (44/74) and 97.0% (32/33) of patients, respectively, with MAC or TB lymphadenitis (P <0.001). Overall, IGRA had a sensitivity of 91.3% (95% CI, 73.2%, 98.4%) and specificity of 96.9% (95% CI, 84.3%, 99.8%) as a test to diagnose TB as the cause of lymphadenitis.

The authors conclude that IGRA can help discriminate between TB and MAC as the cause of submandibular/cervical lymphadenitis in children.

Dr Brady has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion...

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