Role of Endobronchial Therapy in the Management of Primary Tracheo-Bronchial Tumors in Children

Introduction

Primary tracheo-bronchial tumors (PTT) are rare in children, with a reported incidence of 0.049 per 100,000 children (1). These include malignant tumors such as carcinoid tumor (CaT), muco epidermoid carcinoma (MEC), adenoid cystic carcinoma, etc., as well as benign tumors including papillomatosis, hemangiomas, leiomyomas, and inflammatory myofibroblastic tumors (IMT). A surgical approach was considered the treatment of choice for these tumors (2). Advancements in the field of interventional pulmonology have enabled the usage of endobronchial therapeutic (EBT) interventions in the management of varied airway pathologies, including PTT. This can be either curative, especially in benign lesions, or to relieve symptoms of airway obstruction before definitive surgical management can be planned.

Due to its rarity, data regarding the use of bronchoscopic interventions in PTT in children is limited to a few case series (3, 4). We present our intuitional experience on EBT in the management of PTT.

Methods and results

This is a retrospective descriptive study describing children who underwent EBT for PTT during a period of 4 years (from June 2019 to June 2023), at our center in South India. Ethical clearance was not sought after as our institutional policy does not require the same for retrospective research. Data regarding the age, symptoms, radiology, therapy, and follow-up were obtained from the medical records department. During the study period, 5 children (2 male and 3 female) underwent EBT for PTT. The mean age was 8.8 years (2.5-13 years). This included 2 children with IMT and 1 each with CaT, MEC, and Shwannoma. The EBT was curative in 4 children and it proceeded a definitive surgical management in the other. All procedures were done under general anesthesia with a rigid bronchoscopy (Karl-Storz Endoscope). The tumor was successfully debulked in all children, and they have remained recurrence-free for a mean of 23 months (2 months - 48 months).

Case 1

A 13-year-old adolescent female patient, was referred with a 2-month history of non-resolving pneumonia of the left lower lobe. Flexible bronchoscopy revealed a pedunculated polypoid mass at the left main bronchus, completely occluding the lumen (Figure 1. A). A biopsy was done, and a histopathological examination (HPE) revealed a typical CaT (Figure 1. D). As it was a low-grade CT without any extra luminal or nodal involvement on a GA-68 DOTANOC Positron Emission Tomography (PET) scan, an EBT was considered ideal after a multi-disciplinary discussion. The child was intubated with an 11-size rigid bronchoscope. An electrocautery snare was passed through a flexible bronchoscope, the tumor base was excised, and the mass was extracted with a 1.9mm cryoprobe (ERBE, Tübingen, Germany) (Figure 1. B). This was followed up with argon plasma coagulation (APC) (ERBE, Tübingen, Germany) of the tumor base (Figure 1. C). The child has been under follow-up with no documented recurrence, undergoing GA-68 DOTANOC PET scans biannually for the past 4 years.

Case 2

A 2.5-year-old male patient, was referred to us with persistent collapse of the right upper lobe (RUL) of 1 month duration. Computerized tomography of the chest showed a collapse of the RUL with a bronchial cutoff sign. With a suspicion of foreign body aspiration, the child underwent rigid bronchoscopic intubation (size 4) and was found to have a mass originating from the RUL. Mechanical (rigid forceps), as well as cryo-debulking (1.1 mm cryoprobe) of the tumor, was done. The whole tumor was removed in its entirety in a single setting, followed by APC of the base of the tumor. HPE confirmed the mass to be an IMT. An endobronchial biopsy (EBB) of the tumor base, done one month post debulking, was normal, and the child has been on follow-up for 2 years without recurrence.

Case 3

A 13-year-old male patient, was referred because of persisting pneumonia of the RUL. He had three separate admissions for the same reason over the past 6 months and was treated empirically with various antibiotics and anti-tubercular therapy before the referral. At our institute, flexible bronchoscopy revealed a smooth mass protruding from the RUL (Figure 2. A). A biopsy was done and HPE was consistent with MEC, intermediate grade (Figure 2. D). MEC being a malignant tumor, surgical resection was considered most appropriate. However, since the mass was protruding into the main bronchus, right pneumonectomy was the only potential surgical option. Hence, a multi-disciplinary discussion was held, and it was decided to debulk the tumor endoscopically to provide a clear margin in the RUL bronchus, following whith a right upper lobectomy can be the better option as there was no evidence of possible metastasis on PET CT. The child was intubated with an 11-size rigid bronchoscope. Through a flexible bronchoscope, a Neodymium-doped Yttrium Aluminium Garnet (Nd:YAG) laser was inserted through the working channel, targeting the tumor surface. With a pause in ventilation, a targeted pulse laser, 0.5-1 second per pulse, was used to ablate the tumor tissue till a tumor-free margin was achieved in the RUL (Figure 2. B, C). Following this, the patient underwent sleeve lobectomy of RUL as well as the removal of adjacent lymph nodes as a part of routine surgery. Surgical margins were tumor-free and the child has remained recurrence-free for 18 months.

Case 4

A 9-year-old female patient, was brought with complaints of persistent cough and exertional dyspnea lasting for one month. Contrast enhanced computerized tomography of the chest (CT) revealed a polypoid tumor arising from the posterior surface of the trachea with no significant feeder vessels. As she was symptomatic, it was decided to proceed with tumor debulking. The child was intubated with an 11-size rigid bronchoscope. The tumor was seen occluding > 90% of the distal tracheal lumen (Figure 3. A) and looked very friable. Due to the mentioned reasons, we opted for cryotherapy to both devitalize and debulk the tumor. A 1.9mm cryoprobe was inserted through a flexible bronchoscope and pushed into the tumor mass. A touch was enough to dislodge the tumor. After a freeze duration of 4 sec, the flexible bronchoscope and the cryoprobe were pulled out, debulking the tumor (Figure 3. B). This process was repeated 3 times until the entire tumor mass was removed. APC of the tumor base was done (Figure 3. C). HPE was consistent with the diagnosis of IMT (Fig 3 D). Four weeks post-procedure, an EBB of the base was tumor-free. The parents refused surgical excision and opted for regular bronchoscopic surveillance.

Case 5

A 7-year-old female patient, known asthmatic on medications as per GINA guidelines, presented with recurrent hospitalizations for worsening wheezing and exertional dyspnea. At presentation, she was dyspneic at rest with retractions. A contrast-enhanced chest CT showed a mass in the distal trachea arising from the posterior wall of the trachea. While no large vessel supplying the mass could be identified, a late-phase uniform uptake of contrast was noted. As the child was acutely symptomatic, tumor debulking with a curative intent was deemed necessary. A rigid bronchoscope (Size 10) was used to secure the airway and provide access. A polypoidal pedunculated mass was visualized at the distal trachea arising from the posterior membranous wall. An electrocautery snare was employed to sever the tumor at its base and cryo-extracted with the help of a 1.1 mm cryoprobe (ERBE, Tübingen, Germany). APC was applied to the tumor base. Histopathological examination of the specimen revealed a benign nerve sheath tumor consistent with schwannoma. After an uneventful follow-up of six weeks, mucosal biopsies were obtained from the tumor site and confirmed to be free of neoplastic cells.

Discussion

Due to the rare occurrence, there is no consensus on the preferred management for childhood PTT. Data from the adult population recommend EBT for benign tumors as well as malignant tumors with symptomatic obstruction (5). In all of our cases, the airway was secured using a ventilating rigid bronchoscope. Although adult data exists for the use of flexible bronchoscopy alone in airway recanalization (6), we prefer rigid bronchoscopy for all interventional procedures at our institute. This is because using a rigid bronchoscope allows better ventilation, using a jet ventilator, and provides more space to tackle complications such as bleeding. Residual airway stenosis, post-debulking can be managed by mechanical coring using the rigid bronchoscope. A variety of instruments are available in the armamentarium of an interventional pulmonologist for effective debulking of an airway tumor. This includes either hot or cold therapy individually or in combination for effective management (7).

Heat ablative therapy can be achieved with the use of either electrocautery, laser, or APC. Electrocautery uses alternating electric current passed through a probe to generate heat. This can be used to cut, coagulate or vaporize tissue. Heat ablative therapy can be achieved with various instruments such as a snare, knife, blunt probe, and forceps (8). It is highly effective and safe, having negligible major complications and minor complications as low as 6.8% (8). In cases 1 and 5, due to the presence of pedunculated mass, a snare was used to encircle the stalk of the tumor and cut through. APC is a non-contact therapy where high-frequency current is generated by ionized argon gas that thermally destroys tissue. Although it causes rapid coagulation, penetration is only superficial (2-3mm). We routinely perform APC, with a power of 25-30 W, of the tumor base post excision. This is to cauterize superficial blood vessels for hemostasis and to devitalize residual tumor tissue from the base (9).

Laser therapy is another non-contact method for hot therapy, providing both coagulation and vaporization of tumors. Various types of lasers, including CO2, diode, neodymium-doped yttrium-aluminum-garnet (Nd:YAG), and potassium titanyl phosphate (KTP), exist and differ in their wavelengths, depth of penetration, and utility (10). CO2 lasers are the most commonly used in airway surgery, with superficial penetration (0.3 mm/pulse) and reduced thermal diffusion, minimizing injury to adjacent tissues (11). The Nd:YAG laser, which operates at a near-infrared wavelength (1064 nm), offers deeper penetration (up to 10 mm) , making it suitable for cauterizing deeper vessels. However, this increased depth of penetration also raises the risk of transmural injury (11). Due to these risks and the high costs associated with laser therapy, we prefer electrocautery or APC for tumor debulking at our institution. In case 3, the goal was to debulk and ensure a tumor-free margin in the RUL. As an electrocautery snare would not have been ideal and APC would only provide superficial treatment, we opted for laser therapy for debulking. Although a CO2 laser would theoretically have been the preferred tool for this procedure, we used an Nd:YAG laser due to its availability. To minimize complications such as airway fires, we reduced the fraction of inspired oxygen to less than 30% and paused ventilation during all hot therapy procedures.

Cryotherapy uses the Joule-Thompson effect to cause rapid cooling of the tip of the probe. This causes the devitalization of the tumor cells by a combination of immediate (dehydration and cellular ice crystal formation) and delayed (microthrombi formation) effects (12). Unlike hot therapies, it has no risk of airway fires and does not cause airway edema. Furthermore, cartilage and collagen of the airway wall are considered cryo-resistant, hence, there is negligible risk of airway injury (9). In our institute, we use a CO2 cryotherapy machine (ERBE, Tübingen, Germany) with either a 1.1mm or a 1.9mm probe. In cases 1 and 5, cryotherapy was used to extract the tumor after debulking using hot therapy. Mechanical extraction using forceps for airway tumor debulking typically resulted in piecemeal removal. This limitation is overcome with cryo-extraction, which allows for the tumor mass to be removed en bloc. In children 2 and 4, cryotherapy alone was used to debulk the tumor (“freeze and pull” technique of cryorecanalization) (13). Cryotherapy has been documented as safe for pediatric airway interventions, with mild to moderate bleeding being the most common complication (14). It has seen increased adoption in the treatment of adult airway tumors (11). Given the growing body of literature, we anticipate a similar trend in the utilization of cryotherapy for various pediatric interventions.

No major complications occurred during the procedures, and all four children have remained recurrence-free to date. Moderate bleeding was observed in children 1 and 4, which was effectively managed with cold saline application. Given that both hot and cold therapeutic techniques offer distinct advantages and potential complications in airway interventions, we believe that a tailored approach, incorporating a combination of instruments specific to each intervention, is optimal. Our study highlights the effectiveness and safety of various endoscopic therapies in the management of pediatric tracheal and airway tumors.

Conflict of interest

The authors have no conflict of interest to disclose

Data availability statement

Data that supports the findings of the study are available with the corresponding author and will be available on request.

Author contributions

MM, SJT - Writing the original draft and review of the literature, PP - Data collection and review of literature, TC,JM - Review of literature. All authors have read and approved the final draft of this article.

Submitted: December 17, 2024
Accepted: January 21, 2025
Published: February 6, 2025

© 2025 Madhusudan et al. This open-access article is distributed under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0).