Volume 3, Issue 3 , Pages 136-139, September 2008
Non-tuberculous mycobacteria presenting as an obstructing endobronchial mass in an immunocompetent infant
Article Outline
Summary
In immunocompetent children, non-tuberculous mycobacteria infections commonly present as cervicofacial lymphadenitis and seldom cause endobronchial lesions. A 10-month-old presented with unilateral wheezing and radiographic findings of air trapping. During endoscopy, granulation tissue obstructing the left main bronchus was removed, and eventually Mycobacterium avium-intracellulare complex was identified. Serial surgical debridement and prolonged systemic antimicrobials were effective therapeutic interventions.
Keywords: Airway obstruction, Granuloma, Endobronchial mass, Mycobacterium avium-intracellulare, Non-tuberculous mycobacteria, Atypical mycobacteria
1. Introduction
Non-tuberculous mycobacteria (NTM) have a well-known association with lymphadenitis in children. Although pulmonary NTM infections occur in pediatric patients with cystic fibrosis and HIV, isolated endobronchial NTM is rare in immunocompetent children [1], [2]. We report an infant with isolated Mycobacterium avium-intracellulare (MAC) endobronchial infection and discuss controversies in surgical and medical management.
2. Case report
An otherwise healthy 10-month-old girl presented to the emergency room with a chief complaint of wheezing for 2 weeks that was unresponsive to albuterol syrup and prednisolone. There were no symptoms of an associated upper respiratory infection, nor any history of foreign body aspiration, choking, difficulty breathing, or cyanosis. The child appeared well and had occasional wheezes detected by auscultation of her left chest; she had no muscle retractions. A chest radiograph demonstrated hyperinflation of the left lung with air trapping on the left lateral decubitus view; no radiodense foreign body was demonstrated. Bronchoscopy revealed granulation tissue obstructing the proximal left main bronchus, including purulent or foreign white material, and attached to the bronchus posteromedially (Fig. 1). The mass was debulked with optical forceps. Histology and microbiology were suggestive of reactive granulation tissue. No foreign body was identified. Routine bacterial cultures were negative at 72
h. Histopathology demonstrated mixed inflammation, granulation tissue, and giant cells; no acid-fast bacilli or fungal elements were seen.
Fig. 1.
Left main stem endobronchial mass as viewed on initial bronchoscopy.
Direct laryngoscopy and bronchoscopy were repeated 2 weeks later because of clinical suspicion of NTM. A small amount of sessile tissue was also seen and removed from the original site (Fig. 2). Although histology was non-diagnostic, acid-fast cultures from bronchial washings and tissue biopsy were positive for MAC. Clarithromycin, 15mg/kg/day, and rifampin, 10mg/kg/day, were administered pending susceptibility testing. Immunology evaluation revealed normal T-cell immunity by flow cytometry. Her B-cell immunity evaluation included normal IgG, IgM, and IgE, with a borderline low IgA of 4mg/dl and CD 19 (366/mm3; 9.4%), and excellent antibody responses to tetanus and diphtheria vaccine. Human immunodeficiency virus serology testing was negative, and cystic fibrosis was ruled out with a normal chloride sweat test.
Fig. 2.
Residual endobronchial mass 2 weeks after initial debridement.
Three months later, direct laryngoscopy and bronchoscopy demonstrated significant regrowth of the endobronchial lesion, which was again debulked. Histology demonstrated granulomatous inflammation with negative stains and cultures for acid-fast bacilli. Susceptibility testing confirmed resistance to all antimicrobials tested (minimal inhibitory concentrations [MIC]: rifampin, 8mcg/ml; rifabutin, 0.5mcg/ml; ethambutol, 8mcg/ml; streptomycin, 8mcg/ml; amikacin, >8mcg/ml; ciprofloxacin, >4mcg/ml; and linezolid, >16mcg/ml), except for clarithromycin (MIC: <2mcg/ml). Synergy studies showed that in the presence of rifampin, ethambutol MICs dropped to 1mcg/ml (susceptible), and in the presence of ethambutol, MICs to rifampin also dropped to 1mcg/ml (intermediate). Based on the recurrence and microbiology results, 20mg/(kgday) ethambutol was added. Interval endoscopy 4 months after presentation revealed minimal regrowth, which was again debulked, and repeat endoscopic evaluation 7 months after presentation revealed only a small amount of residual abnormal tissue. In both instances, tissue and bronchial aspirates for AFB stains and cultures were negative. Antimicrobial therapy was maintained for 7 months. Bronchoscopy performed 18 months after presentation demonstrated complete resolution of the endobronchial lesion (Fig. 3).
Fig. 3.
Left main stem bronchus at final bronchoscopy, with complete resolution of endobronchial mass.
3. Discussion
MAC infections have become increasingly important to consider in recent years, particularly in association with HIV and cystic fibrosis, but also in otherwise healthy children and adults [2]. In children, 80% of NTM infections are attributed to MAC, 16% to Mycobacterium scrofulaceum, and 3% to Mycobacterium kansasi [3]. The most common presentation of MAC infections in immunocompetent children is cervicofacial lymphadenitis [4]. MAC, like most NTM, is ubiquitous in the environment and frequently found in soil and water. Pulmonary infection has been associated with inhalation of aerosolized MAC particles generated by different sources, including hot tubs and spas.
Intrathoracic manifestations of NTM disease are uncommon in immunocompetent children and may include endobronchial masses, pneumonia with cavitary lesions, mediastinal lymphadenopathy, extrinsic bronchial compression, endobronchial lesions, and invasive disease [2], [5], [6]. Nolt et al. aggregated the literature describing 43 pediatric cases of intrathoracic NTM disease in immunocompetent children; combining endobronchial, pulmonary and mediastinal manifestations [2]. All patients presented with cough, wheezing, or both; 60% also demonstrated constitutional signs and symptoms. In four cases, foreign body aspiration was the preliminary diagnosis, and one-third of chest radiographs demonstrated asymmetric air trapping [2]. As in cervicofacial NTM, the most common NTM infection in Caucasian toddlers was MAC [2]. Nolt et al. conclude that the length of medical therapy has not been standardized, single-drug regimens have not proven effective, and surgical therapy appears to hasten clinical cure [2].
Although surgical management of cervical MAC infections remains controversial, surgical debulking and, in selected cases, serial curettage remain essential components of therapy for endobronchial NTM lesions, as with our case. Both forceps and lasers have been used to debulk the lesions [7], [8].
Antibiotic therapy typically utilizes a combination of drugs to both address and prevent further resistance. Possible therapeutic agents include macrolides, quinolones, rifamycins, aminoglycosides, and ethambutol [9]. Newer antimicrobial agents with in vitro activity against MAC, including linezolid and novel oxazolidinones, such as such DA-7867 and DA-7157, are currently under development [10]. Susceptibility testing for MAC has not been standardized. Although tailoring therapy to in vitro results remains controversial, it is recommended for immunocompromised hosts, patients who fail to improve, and invasive disease [1].
Duration of therapy for endobronchial MAC in immunocompetent children has not been standardized. Our patient completely recovered after 7 months of antimicrobial therapy and serial surgical debridement. In adult patients with intrapulmonary NTB, therapy is empirically extended for 12 months after the sputum is negative. These prolonged courses of therapy may not be needed in immunocompetent pediatric patients with endobronchial lesions undergoing serial surgical resections. Similarly, corticosteroids are routinely recommended in patients with endobronchial Mycobacterium tuberculosis; however, there is limited experience reported in children with disseminated MAC and/or endobronchial NTM infection.
4. Summary
Endobronchial NTM is an uncommon cause of wheezing in immunocompetent children and may present in a manner suggestive of foreign body aspiration. Generally, endobronchial NTM infections behave in an indolent manner, similar to cervicofacial NTM. Despite laboratory testing, the diagnosis may be difficult to confirm, and resolution may require a combination of serial debridement and antibiotics.
Conflict of interest
All authors attest that they have no conflict of interest, financial or otherwise, to disclose.
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PII: S1871-4048(08)00008-7
doi:10.1016/j.pedex.2008.01.007
© 2008 Elsevier Ireland Ltd. All rights reserved.
Volume 3, Issue 3 , Pages 136-139, September 2008
