Two Case Reports of Drug-Resistant Tuberculous Pleurisy in Children: Thoracoscopic Pleural Biopsy and PCR-Based Drug-Resistance Testing

Abstract

Background

Drug-resistant tuberculous pleurisy is difficult to diagnose in children because pleural fluid is paucibacillary, culture is slow and frequently negative, and Xpert detects only rifampicin resistance.

Case Presentation

We report two children in whom thoracoscopic pleural biopsy combined with PCR-high-resolution melting (HRM) drug-resistance testing identified drug-resistant tuberculosis. Case 1, an 8-year-old girl with tuberculous pleurisy, showed persistent pleural thickening and a new mass after two months of standard first-line therapy; pleural tissue PCR detected rpoB and inhA mutations, confirming multidrug-resistant tuberculosis (MDR-TB), and she responded to an all-oralbedaquiline- and delamanid-containing regimen. Case 2, a 9-year-old boy with loculated tuberculous pleurisy and negative cultures, had an rpoB mutation confirming rifampicin-monoresistant tuberculosis; he recovered with a rifampicin-sparing regimen and remained relapse-free at one year.

Conclusion

In pediatric tuberculous pleurisy, particularly when fluid-based testing is uninformative or first-line therapy fails, thoracoscopic pleural biopsy combined with molecular drug-resistance testing of tissue is decisive for detecting occult drug-resistant tuberculosis and enabling timely, individualized treatment.

Introduction

Tuberculous pleurisy is a common form of extrapulmonary tuberculosis in children and generally responds well to first-line anti-tuberculosis therapy.^1,2 However, a subset of patients respond poorly because of loculated effusion, superinfection, an alternative diagnosis such as malignancy, or unrecognized drug resistance.³ In these cases, microbiological confirmation from pleural fluid is frequently negative owing to the paucibacillary nature of the disease, and culture-based drug susceptibility testing is slow, creating a diagnostic impasse.

Conventional diagnostic tools each have important limitations. Pleural fluid adenosine deaminase (ADA) is suggestive but not specific.⁴ Interferon‑gamma release assays are sensitive but limited by false positives.⁵ Acid-fast bacillus smear has low sensitivity,⁶ and Xpert MTB/RIF detects only rifampicin resistance and performs poorly in pleural fluid, with sensitivity of 34–51%.^7,8 In contrast, thoracoscopic pleural biopsy provides a high diagnostic yield (up to 100%) by obtaining tissue with a high bacillary load and characteristic pathology.^9,10. PCR-based high-resolution melting (HRM) analysis of tissue can then identify resistance mutations for multiple drugs rapidly.^11–13 HRM detects resistance mutations by monitoring the melting-temperature shift of PCR-amplified target gene regions. Applied to pleural tissue, which has a higher mycobacterial load than pleural fluid, it also interrogates several resistance genes simultaneously; in contrast, Xpert targets rpoB alone and has low sensitivity in paucibacillary pleural fluid, so HRM provides broader and more sensitive drug-resistance profiling in pleural disease.

Here we report two children with drug-resistant tuberculous pleurisy—one presenting with first-line treatment failure and one diagnosed upfront during thoracoscopy for loculated disease—in whom thoracoscopic pleural biopsy combined with PCR-based drug-resistance testing established the definitive diagnosis and enabled individualized, effective treatment.

Case Presentation

Case 1: Multidrug-Resistant Tuberculous Pleurisy

An 8-year-old, previously healthy girl with no known comorbidities or underlying conditions, who had received a full course of Bacille Calmette-Guérin (BCG) vaccination presented with a four-month history of recurrent fever. Initial chest computed tomography (CT) showed right lung consolidation with pleural effusion. Bronchoalveolar lavage fluid testing (Xpert MTB/RIF, mycobacterial culture, and metagenomic next-generation sequencing) was negative, and empirical antibiotics temporarily resolved the fever. Three months before admission, follow-up imaging revealed a new nodular mass in the right chest wall. Diagnostic thoracentesis yielded an exudative lymphocytic effusion with an elevated ADA level (42 U/L); the tuberculin skin test (11 mm induration) and interferon-gamma release assay were positive. Primary pulmonary tuberculosis with tuberculous pleurisy was diagnosed, and standard first-line therapy (isoniazid, rifampicin, pyrazinamide, and ethambutol [HRZE]) was started together with oral prednisone. After two months, although the lung parenchyma and effusion improved partially, marked pleural thickening and a mass lesion persisted (Figure 1a–d); drug-resistant tuberculosis and malignancy were considered.

Figure 1.

Chest computed tomography of Case 1. (a–d) Persistent right pleural thickening and a pleural-based mass after two months of standard first-line (HRZE) therapy. (e–h) Marked regression of the pleural thickening and mass two months after switching to an all-oral bedaquiline- and delamanid-containing regimen. The green arrow indicates the mass, and the red arrow indicates pleural thickening.

For a definitive diagnosis, she underwent video-assisted thoracoscopic surgery (VATS), which showed dense pleural adhesions and a fibrous peel; adhesiolysis exposed a 6-cm caseous necrotic mass on the anterior chest wall. Tissue was sent for histopathology, acid-fast bacillus (AFB) smear, mycobacterial culture, and targeted PCR for drug-resistance genes. Drug-resistance testing was performed on pleural tissue obtained by thoracoscopic biopsy using a real-time fluorescent PCR with probe-based melting-curve analysis (high-resolution melting, HRM). The assay was performed by the hospital’s clinical molecular diagnostics laboratory as part of routine clinical testing. It simultaneously identified the Mycobacterium tuberculosis complex and detected drug-resistance-associated genes: rpoB (rifampicin), katG and inhA (isoniazid), and gyrA (fluoroquinolones). DNA was extracted from the tissue according to standard laboratory procedures. Primers and probes were those supplied with the assay and are proprietary. Histopathology confirmed granulomatous inflammation with caseous necrosis. PCR detected rpoB (codons 507–512) and inhA (codon 94) mutations in the Mycobacterium tuberculosis complex, confirming resistance to rifampicin and isoniazid (multidrug-resistant tuberculosis [MDR-TB]); AFB smear and culture of the same tissue remained negative.

Following multidisciplinary review, treatment was changed to an individualized all-oral regimen of bedaquiline, delamanid, linezolid, pyrazinamide, and levofloxacin, consistent with WHO-recommended all-oral management of multidrug-resistant/rifampicin-resistant tuberculosis.¹⁴ Two months after the change, chest CT showed significant regression of the pleural thickening and mass (Figure 1e–h). The patient remains on treatment under close monitoring.

Case 2: Rifampicin-Monoresistant Tuberculous Pleurisy

A 9-year-old, previously healthy with no known comorbidities or underlying conditions, BCG-vaccinated boy presented with a three-month history of dry cough and a six-day history of high-grade fever (peak 41°C). Examination showed fullness of the right hemithorax, diminished breath sounds, and dullness to percussion over the right mid and lower zones. High-sensitivity C-reactive protein was markedly elevated (112.3 mg/L); the tuberculin skin test (12 mm induration) and interferon-gamma release assay were positive. Contrast-enhanced chest CT demonstrated a moderate loculated right pleural effusion with pleural thickening, consolidation, and right lung atelectasis (Figure 2a and b).

Figure 2.

Chest computed tomography of Case 2. (a and b) Moderate loculated right pleural effusion with pleural thickening, consolidation, and atelectasis at presentation. (c and d) Residual focal pleural thickening with early calcification after completion of treatment. The green arrow indicates the mass, and the red arrow indicates pleural thickening.

Because the effusion was loculated, he underwent VATS for both therapeutic drainage and definitive biopsy; dense adhesions and fibrinous material were seen intraoperatively. Histopathology of the pleural tissue showed caseous necrosis with fibrous tissue proliferation. Mycobacterial cultures of pleural fluid and tissue were negative after standard incubation. However, PCR-based molecular testing of the pleural tissue identified M. tuberculosis complex DNA and an rpoB mutation, confirming rifampicin-monoresistant tuberculous pleurisy.

He received a rifampicin-sparing regimen: an intensive six-month phase with levofloxacin, linezolid, pyrazinamide, isoniazid, and ethambutol, followed by a twelve-month continuation phase with levofloxacin and linezolid. He had an excellent clinical and radiological response; follow-up CT after completion of treatment showed only residual focal pleural thickening with early calcification (Figure 2c and d). He remained asymptomatic with no relapse during one year of post-treatment surveillance.

The key clinical, diagnostic, and therapeutic features of the two cases are summarized and compared in Table 1.

Table 1.

Comparison of the Two Pediatric Cases of Drug-Resistant Tuberculous Pleurisy

Feature	Case 1	Case 2
Age / sex	8-year-old girl	9-year-old boy
Presentation	4-month recurrent fever	3-month dry cough; 6-day high fever (41°C)
Initial imaging	Right consolidation and effusion; later new chest-wall mass	Loculated right effusion, thickening, consolidation, atelectasis
Initial non-invasive tests	ADA 42 U/L; TST and IGRA positive; BALF Xpert/culture/mNGS negative	CRP 112.3 mg/L; TST and IGRA positive
Initial treatment	HRZE plus prednisone for 2 months	None before diagnosis
Response to initial treatment	Persistent thickening and mass	Not applicable
Definitive procedure	VATS biopsy of 6-cm caseous mass	VATS drainage and pleural biopsy
Histopathology	Granulomatous inflammation with caseous necrosis	Not described
Molecular finding	rpoB (507–512) and inhA (94) mutations	rpoB mutation
Final diagnosis	Multidrug-resistant tuberculous pleurisy	Rifampicin-monoresistant tuberculous pleurisy
Definitive regimen	Bedaquiline, delamanid, linezolid, pyrazinamide, levofloxacin	6-mo levofloxacin + linezolid + pyrazinamide + isoniazid + ethambutol; then 12-mo levofloxacin + linezolid
Outcome	Marked CT regression at 2 months; on treatment	Complete recovery; no relapse at 1 year

Abbreviations: ADA, adenosine deaminase; BALF, bronchoalveolar lavage fluid; CRP, C-reactive protein; CT, computed tomography; HRZE, isoniazid, rifampicin, pyrazinamide, ethambutol; IGRA, interferon-gamma release assay; mNGS, metagenomic next-generation sequencing; TST, tuberculin skin test; VATS, video-assisted thoracoscopic surgery.

Discussion

Tuberculous pleurisy is typically paucibacillary, and establishing the diagnosis—let alone drug resistance—is especially difficult in children. Both patients illustrate a common clinical trap: pleural fluid and even bronchoalveolar lavage are repeatedly negative, an initial diagnosis is made on clinical and immunological grounds, and treatment decisions are made without microbiological confirmation. In Case 1, first-line therapy was continued for two months without benefit until drug resistance was sought; in Case 2, an upfront tissue-based approach shortened the time to a definitive resistance profile.

The decisive step in both cases was moving from fluid-based to tissue-based diagnosis. Thoracoscopic biopsy achieves high diagnostic sensitivity (up to 100%) and simultaneously provides tissue for both histopathology and molecular testing.^9,10 Histopathology establishes or supports tuberculosis and helps exclude malignancy, while PCR/high-resolution melting analysis of tissue detects resistance mutations across multiple drugs rapidly, overcoming the limitation of Xpert, which detects rifampicin resistance only and has low sensitivity in pleural fluid.^7,8 HRM-based assays have shown high sensitivity and specificity for rifampicin, isoniazid, and fluoroquinolone resistance, including in formalin-fixed, paraffin-embedded tissue.^11–13

The two cases span the spectrum of drug-resistant tuberculous pleurisy: MDR-TB (resistance to rifampicin and isoniazid) and rifampicin-monoresistant tuberculosis. Identification of the resistance profile directly determined treatment. Case 1 was treated with an all-oral bedaquiline- and delamanid-containing regimen, whereas Case 2, with rifampicin monoresistance, could be managed with a rifampicin-sparing regimen (fluoroquinolone, linezolid, and companion drugs), in line with WHO guidance for drug-resistant tuberculosis.¹⁴ Both responded well, emphasizing that precise drug-susceptibility information translates into effective, individualized therapy and avoids prolonged exposure to an ineffective regimen.

A practical clinical lesson is that an inadequate response to standard first-line therapy—or loculated disease that prevents informative fluid sampling—should trigger early tissue sampling rather than prolonged empirical escalation. Where thoracoscopy is available, it can be diagnostic and therapeutic in a single procedure (drainage, adhesiolysis, and biopsy) and provides the optimal specimen for molecular drug-susceptibility testing. VATS is minimally invasive and, when performed by an experienced team, is generally safe and well tolerated in children, with a low rate of major complications.¹⁵ Early VATS is therefore justified to obtain diagnostic tissue when pleural fluid testing is negative or first-line therapy is failing, while avoiding the greater morbidity of open thoracotomy. The main limitations of this report are its small sample size (two patients), its retrospective design, and the still-ongoing follow-up of Case 1; nevertheless, the cases are instructive and reproducible in high tuberculosis-burden settings.

Conclusion

Tuberculous pleurisy in children should prompt early escalation to VATS when fluid-based assays remain inconclusive or first-line therapy fails. This approach rapidly identifies occult drug-resistant tuberculosis and guides timely, individualized treatment, improving outcomes in a diagnostically challenging scenario.

Funding Statement

This work was supported by the National Science and Technology Major Project of China (No. 2025ZD01907802).

Abbreviations

ADA, adenosine deaminase; AFB, acid-fast bacilli; BCG, bacille Calmette-Guérin; CT, computed tomography; HRM, high-resolution melting; HRZE, isoniazid, rifampicin, pyrazinamide, ethambutol; MDR-TB, multidrug-resistant tuberculosis; PCR, polymerase chain reaction; RR-TB, rifampicin-resistant tuberculosis; TB, tuberculosis; VATS, video-assisted thoracoscopic surgery; WHO, World Health Organization.

Data Sharing Statement

All data generated or analyzed during this study are included in this published article.

Ethics Approval and Informed Consent Statement

Written informed consent for the publication of the case details and accompanying images was obtained from the legal guardians of both patients. This study was approved by the Ethics Committee of West China Second University Hospital, Sichuan University. Institutional approval was not required for publication of the case details. The whole research process follows the Declaration of Helsinki.

Consent for Publication

Written informed consent was obtained from the legal guardians of both patients for publication of the case details and any accompanying images.

Disclosure

The authors report no conflicts of interest in this work.