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correspondence

Indian Pediatr 2013;50: 803-804

Tuberculosis - A Quest Towards Objectivity

A Gupta

Department of Pediatrics and Neonatology,  Fortis Hospital and Research Centre, Faridabad, India.
Email:
[email protected]
 


I read with interest "updated National Guidelines for pediatric tuberculosis in India, 2012" and appreciate the effort made to clarify certain grey areas of interpretation like weight loss or no weight gain besides presenting the contents as flow diagrams for ready reference [1]. I would like to draw attention to certain points requiring further clarification to enable a clinician to use these guidelines practically and effectively in a wider range of situations.

According to figure 1a and 1b, a symptomatic sputum negative patient undergoes chest X-ray and TST. Following this, the possible results would be in six ways as per the outcome of these two investigations.

Chest X-ray can be read as: (a) Highly suggestive of tuberculosis, (b) Non- specific shadows (c) Normal; TST can be read as: (i) Positive, (ii) Negative. Though most of the possible scenarios are dealt with properly, it does not provide an approach for (a+ii) that is highly suggestive XRC and TST negative. Similarly it does not justify the use of TST when XRC shows non- specific shadows as no decision is based on TST results whether positive or negative.

CT scan is a useful diagnostic modality in children when tuberculosis is suspected and the radiographic findings are normal or inconclusive [2]. Chest CT can help to identify enlarged, calcified, necrotic mediastinal lymph nodes, which are less frequently found in community acquired bacterial pneumonia and frequently obscured by thymic shadows on chest radiographs of children [3]. It may also detect pulmonary parenchymal lesions not otherwise visualized on chest radiographs [4]. Therefore, a TST positive, sputum negative clinical suspect in such scenario may be subjected to CT scan chest as first investigation (wherever possible) before taking on other investigation for alternate diagnosis.

As tuberculin skin test is defined with the use of tuberculin 2 TU and its procurement is difficult outside government supply, it would be useful to share the manufacturer of such product.

References

1. Kumar A, Gupta D, Sharath BN, Singh V, Sethi GR, Prasad J. Updated National Guidelines for pediatric tuberculosis in India, 2012. Indian Pediatr. 2013;50:301-13.

2. Kim WS, Moon WK, Kim IO, Lee HJ, Im JG, Yeon KM,  et al. Pulmonary tuberculosis in children: evaluation with CT. Am J Roentgenol. 1997;168:1005-9.

3. Peng SS, Chan PC, Chang YC, Shih TT. Computed tomography of childrenwith pulmonary  Mycobacterium  tuberculosis infection. J Formos Med Assoc. 2011; 110:744-9.

4. Swaminathan S, Raghavan A, Datta M, Paramasivan CN, Saravanan KC. Computerized tomography detects pulmonary lesions in children with normal radiographs diagnosed to havetuberculosis. Indian Pediatr. 2005; 42:258-61.

 

Reply

The author has raised the issue about dealing with children with highly suggestive radiology, who are TST negative. With certainty it is spelt out in the diagnostic algorithm that a presumptive pediatric TB case with TST negative and chest X-ray findings suggestive of TB should be diagnosed based on X-ray findings; because the TST suffers from lack of sensitivity and specificity, and there are operational issues concerned with performing the test efficiently. In view of radiation risk and issues pertaining to CT interpretation (low specificity and inter observer variability) [1,2] it is neither necessary nor appropriate to recommend CT scan as first line investigation. However, the algorithm has identified situations where an expert opinion is needed and they may ask for more detailed investigations including CT chest.

Varinder Singh and BN Sharath
Email: [email protected]

References

1. Andronikou S, Brauer B, Galpin J, Brachmeyer S, Lucas S, Joseph E, et al. Interobserver variability in the detection of mediastinal and hilar lymph nodes on CT in children with suspected pulmonary tuberculosis. Pediatr Radiol. 2005;35:425-8.

2. de Jong PA, Nievelstein RJ. Normal mediastinal and hilar lymph nodes in children on multi-detector row chest computed tomography. Eur Radiol. 2012;22:318-21.

 

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