Bronchoscopic photodynamic therapy for endobronchial metastatic papillary thyroid carcinoma causing lobar airway obstruction: a case report

Introduction

Background

Malignant airway obstruction (MAO) can cause dyspnea and post-obstructive complications, and therapeutic bronchoscopy requires individualized selection based on anatomy, urgency, bleeding risk, and local expertise (1). Photodynamic therapy (PDT) is a bronchoscopic, non-thermal tumor ablation technique approved for malignant endobronchial disease, including palliation of obstructing endobronchial non-small cell lung cancer (2). After administration of a photosensitizer, bronchoscopic light activation generates reactive oxygen species that produce tumor cytotoxicity, microvascular shutdown, and delayed necrosis and sloughing (3-5).

Rationale and knowledge gap

Because necrotic debris can transiently worsen airway patency, repeat bronchoscopy for debridement is typically required within 48–72 hours, with repeat illumination when residual disease persists (2,5). While PDT is well described in primary lung malignancy and superficial endobronchial neoplasia, published experience in non-lung-primary endobronchial metastases remains limited (3-7).

Objective

We report a staged bronchoscopic PDT approach for highly vascular endobronchial metastatic papillary thyroid carcinoma (PTC) causing lobar airway obstruction. We present this article in accordance with the CARE reporting checklist (available at https://atm.amegroups.com/article/view/10.21037/atm-2026-0057/rc).

Case presentation

A 71-year-old never-smoking woman with advanced radioactive iodine (RAI)-refractory BRAF V600E-mutated PTC with pulmonary, brain, and bone metastases presented with evidence of a progressive posterior-medial left lower lobe (LLL) lesion with endobronchial extension on chest computed tomography (CT) (Figure 1). Her oncologic history included total thyroidectomy complicated by right vocal cord paralysis requiring prior medialization, radioiodine therapy, redifferentiation therapy with dabrafenib followed by additional radioiodine, stereotactic radiosurgery for brain metastases, and stereotactic radiotherapy to the left femoral metastasis (Table 1). She had no prior thoracic radiation.

Figure 1 Representative chest computed tomography images demonstrating the left lower lobe lesion with endobronchial extension and progressive airway involvement. LLL, left lower lobe.

She reported exertional dyspnea without resting symptoms. Resting oxygen saturation was normal, and there was no stridor. She denied hemoptysis or infectious symptoms.

Flexible bronchoscopy revealed a friable, highly vascular tumor causing approximately 90% obstruction of the LLL bronchus and a smaller non-occlusive lesion in the superior segment of the right lower lobe (RLL) (Figure 2A,2B). Endobronchial biopsy confirmed metastatic PTC (Figure 3). Because immediate mechanical or thermal debulking was considered high risk for hemorrhage, a staged bronchoscopic PDT strategy was selected.

Figure 2 Chronologic bronchoscopic appearance: endobronchial metastatic PTC treated with PDT. Bronchoscopic images showing the hypervascular near-obstructing left lower lobe endobronchial lesion, the smaller RLL superior segment lesion, interval necrotic change after photodynamic therapy, and improved airway patency after staged intervention. (A) Baseline bronchoscopy demonstrating near-occlusive LLL endobronchial tumor; (B) RLL superior segment endobronchial tumor (arrow), biopsy proven metastatic PTC prior to PDT therapy; (C) PDT light activation delivered to the LLL tumor via cylindrical diffuser; (D) PDT light activation delivered to the adjacent RLL endobronchial lesion; (E) LLL bronchus 72 hours after initial PDT demonstrating tumor necrosis and improved luminal patency; (F) RLL lesion 72 hours after initial PDT with partial response and necrotic change; (G) Cryotherapy removal of necrotic LLL tumor resulting in restoration of complete airway patency; (H) Surveillance bronchoscopy demonstrating complete resolution of the RLL superior segment lesion. LLL, left lower lobe; PDT, photodynamic therapy; PTC, papillary thyroid carcinoma; RLL, right lower lobe.

Figure 3 Histopathology (H&E): papillary thyroid carcinoma morphology. Microscopic pathology images of endobronchial biopsy/cryobiopsy showing papillary neoplasm with fibrovascular cores lined by tumor cells with enlarged crowded nuclei, pale chromatin, occasional nuclear grooves, and intranuclear pseudoinclusions, consistent with metastatic papillary thyroid carcinoma. (A) Low power (2×): papillary neoplasm with complex papillary fronds. (B) Intermediate power (10×): finger-like papillae with fibrovascular cores. (C) High power (40×): tumor cells with enlarged, crowded nuclei and pale chromatin; nuclear grooves may be present. (D) High power (40×): tumor cells demonstrating intranuclear pseudoinclusions. H&E, hematoxylin and eosin.

Per institutional protocol, porfimer sodium (Photofrin; 2 mg/kg IV; Pinnacle Biologics) was administered before light activation. Bronchoscopic light activation was performed using 630-nm laser light through a 2-cm cylindrical diffuser fiber, with planned relook bronchoscopy within 48–72 hours for airway toileting, response assessment, and repeat light application if indicated.

During PDT session #1, rigid bronchoscopy under general anesthesia again demonstrated a near-obstructing, highly vascular LLL endobronchial mass and a smaller vascular lesion in the RLL superior segment. PDT was delivered to both lesions using a 2-cm diffuser at 630 nm, with 100 J over 250 seconds per site (Figure 2C,2D). For the bulky LLL lesion, an intratumoral (“impaling”) technique was used to optimize light delivery; a parallel technique was used for the RLL lesion.

At repeat bronchoscopy with PDT session #2 approximately 72 hours later, bronchoscopy demonstrated about 50% reduction in endoluminal tumor burden at both sites with necrotic debris (Figure 2E,2F). Therapeutic suctioning and removal of debris were performed, followed by repeat light application using the same parameters.

At bronchoscopy approximately 1 week after initial PDT, necrotic post-PDT changes were present. Additional debridement was performed using cryotherapy, restoring distal airway patency (Figure 2G), and biopsy of the LLL lesion again demonstrated metastatic PTC with associated acute inflammation. Dabrafenib, a BRAF kinase inhibitor, was initiated approximately 1 month after PDT. At surveillance bronchoscopy approximately 2 months after PDT, a residual LLL lesion remained without significant obstruction; cryodebulking improved distal airway patency, and the RLL lesion had completely resolved endoscopically (Figure 2H).

Airway patency was maintained after staged PDT. Representative pre- and post-treatment chest CT images demonstrated near-complete obstruction of the LLL bronchus before PDT and subsequent recanalization of the LLL bronchus after treatment (Figure 4). Follow-up chest CT approximately 3 months after PDT showed mild decrease in the dominant LLL mass and otherwise stable pulmonary metastatic disease, with no new lesions. At clinical follow-up, she had Eastern Cooperative Oncology Group (ECOG) 0 and denied cough, hemoptysis, or dyspnea, and continued dabrafenib. No major bleeding, airway compromise, pneumothorax, or other procedural complications occurred.

Figure 4 Pre- and post-treatment chest CT after staged bronchoscopic PDT. (A) Pre-treatment chest CT demonstrating tumor invading the LLL bronchus with near-complete obstruction (arrow). (B) Follow-up chest CT after PDT demonstrating recanalization of the LLL bronchus (arrow). CT, computed tomography; LLL, left lower lobe; PDT, photodynamic therapy.

A consolidated diagnostic and therapeutic timeline is provided in Table 1.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Key findings

Endobronchial PDT is an established bronchoscopic modality with two major clinical domains: definitive therapy for selected early, centrally located airway cancers and palliation of MAO in non-small cell lung cancer (NSCLC) (1-3). In early-stage central airway disease, PDT has been used for carcinoma in situ and carefully selected stage I, centrally located tumors, reflecting its ability to achieve local tumor control while preserving airway architecture in appropriately staged patients and with a depth of penetration of about 1–1.5 cm (2,3). In contrast, the evidence base for primary peripheral early-stage lung cancers remains limited; one of the best-described experiences is a CT-guided percutaneous approach in a small cohort in which partial responses were observed, underscoring that peripheral use has not reached the same level of evidence as central airway applications (4).

For MAO, PDT is guideline-supported and widely recognized as a useful palliative option, particularly when symptom relief and restoration of airway patency are the near-term objectives (1,5-7). A randomized trial comparing PDT with Nd:YAG laser resection in inoperable NSCLC with airway obstruction demonstrated symptomatic improvement in both groups, with longer time to treatment failure in the PDT arm (5). Larger cohort data also support symptomatic benefit: in a series of patients with airway lesions treated with PDT, dyspnea improved in most patients, and PDT was considered particularly well suited for bloody tumors obstructing the tracheobronchial tree, including severely debilitated patients who may not tolerate alternative debulking approaches (6). Collectively, these data support the practical role of PDT in MAO, often as part of a multimodality therapeutic bronchoscopy strategy rather than a single stand-alone intervention (1,5-8).

Strengths and limitations

To the best of our knowledge, this is the first reported case of successful PDT of endobronchial metastases from metastatic PTC. Strengths include a protocolized staged approach with planned relook bronchoscopy and airway toileting, selection of a non-thermal modality in a hypervascular lesion where conventional debulking was judged high risk, and clinically meaningful endobronchial outcomes, including durable RLL endobronchial response and improved LLL patency, that enabled subsequent bronchoscopic management and integration with systemic oncologic therapy.

Limitations are inherent to single-patient reporting, including limited generalizability, potential confounding from concurrent systemic therapy and evolving tumor biology, and inability to define optimal dosimetry or retreatment strategy for metastatic PTC from one case. These limitations underscore the need for multicenter registries or series focused on non-lung-primary endobronchial metastases, with standardized reporting of lesion vascularity, intraluminal length, degree of obstruction, retreatment cadence, and objective symptom and physiology endpoints.

Comparison with similar research

Mechanistically, PDT combines administration of a photosensitizer followed by illumination at an appropriate wavelength in the presence of oxygen, generating reactive oxygen species that drive direct tumor cell death, microvascular injury and shutdown, and a local inflammatory response that can augment antitumor immunity (3,9-11). These convergent effects are central to the appeal of PDT in hypervascular or bleeding-prone endobronchial tumors: microvascular injury and downstream necrosis may reduce the immediate bleeding risk compared with mechanical or thermal debulking in selected scenarios (6,9,11,12). However, the same delayed necrosis that underlies tumor control also creates a predictable post-treatment airway management issue—sloughing and accumulation of necrotic debris can transiently worsen airway patency and therefore necessitate repeat bronchoscopy for necrotic debris removal and response assessment (3,6-8,11,12,23). In practical terms, this planned relook is not merely surveillance; it is a safety-critical step that operationalizes PDT as a staged therapy, particularly for obstructing lesions and those treated at higher energy densities (6,7,12,23).

Careful patient selection is central to safe and effective PDT. Across guidance and contemporary reviews, the best candidates are those with a predominantly intraluminal tumor component and a recruitable distal lung unit, where restoring airway patency is expected to translate into clinical improvement (1,2,7,24). Conversely, obstruction that is purely extrinsic compression is not amenable to PDT, given the requirement for direct illumination of the target tissue (2,7). In addition, because PDT’s effect is delayed, it is generally not favored as sole therapy for immediately life-threatening obstruction in which an instantaneous debulking effect is required; in such scenarios, immediate-acting modalities such as mechanical coring, laser, electrocautery/argon plasma coagulation (APC), or cryotherapy are typically prioritized, with PDT used later for longer-lasting local control when appropriate (1,7,8).

Pre-procedural staging and assessment of tumor extent also matter. For curative-intent PDT in early central airway lesions, evaluation of airway wall invasion is critical; endobronchial ultrasound has been shown to refine candidacy by identifying deeper invasion that may not be appreciated by bronchoscopy and CT alone, thereby reducing inappropriate selection for curative PDT (25). While our case was treated with palliative and adjunctive rather than curative intent, the broader principle remains relevant: depth and extraluminal extension predict incomplete local eradication, and the therapeutic aim should be framed accordingly (2,7,25). Prior work comparing single- versus multimodality bronchoscopic palliation, including PDT alongside stents, brachytherapy, and other ablative techniques, suggests that multimodality strategies may be associated with improved outcomes in selected populations, supporting an integrated approach rather than rigid modality silos (26).

Explanations of findings

A key limitation of endobronchial PDT is its finite depth of effect, which is driven by optical tissue properties, light delivery geometry, and the absorption wavelength of the photosensitizer (2,8,13,14). First-generation porphyrin-based photosensitizers such as porfimer sodium are activated at approximately 630 nm, a wavelength that yields relatively limited tissue penetration compared with some second-generation agents (3,13,14). Second-generation photosensitizers can increase effective depth under certain conditions, yet even with newer agents, endobronchial PDT cannot reliably eradicate disease extending beyond bronchial cartilage or with substantial extra cartilaginous invasion (2,8,13-15). The practical depth of effect is commonly cited in the millimeter range and is influenced by tumor characteristics, timing of illumination, and light delivery parameters (14,23). From a clinical standpoint, this means PDT should often be conceptualized as a local endobronchial control strategy: it can debulk intraluminal tumor and restore or maintain patency, but bulky lesions with extraluminal or parenchymal extension generally require systemic therapy and/or radiation-directed approaches for durable disease control (2,7,13,14,24). This framework directly explains the pattern observed in our patient—complete response in the smaller RLL endobronchial lesion and partial but expected response in the larger, near-occlusive LLL lesion, where residual extraluminal tumor burden persisted despite improved endobronchial patency.

Recognition of PDT’s depth constraints has also driven multimodal strategies, including mechanical debulking followed by PDT for residual endobronchial disease when safe, PDT integrated with chemoradiation or endobronchial brachytherapy in selected advanced cases, and intraoperative or perioperative PDT incorporated with surgical approaches in specialized settings (13,14,16,27). These strategies acknowledge that PDT alone may not address the full tumor burden in bulky lesions and emphasize careful coordination with thoracic oncology and radiation oncology.

The published experience of PDT for non-lung-primary endobronchial metastases remains limited despite endobronchial metastasis being a recognized but uncommon clinical entity (17,18). Tumor biology and vascularity can materially shape the risk-benefit profile of endobronchial interventions. PDT has been reported in select endobronchial metastases, such as renal cell carcinoma and melanoma, where bleeding risk and tumor friability can limit conventional debulking techniques (19,20). In addition, large institutional experience from Ohio State describes PDT as an effective alternative for palliation of hemoptysis and obstructive metastatic airway disease, with a low complication rate, and highlights the importance of systematic technique and longitudinal bronchoscopic follow-up (12).

Our case extends this framework to a rare presentation: highly vascular endobronchial metastatic PTC causing lobar airway obstruction. PTC is frequently driven by actionable molecular alterations, including BRAF-pathway alterations, in advanced disease, and treatment increasingly relies on multidisciplinary integration of systemic targeted therapies, radiotherapy, and local control strategies (21). The role of PDT in thyroid cancer overall remains limited and is largely discussed in preclinical and early clinical contexts, emphasizing the need for cautious interpretation and targeted application (23). In the present case, PDT was selected because the dominant LLL endobronchial lesion was nearly occlusive and markedly vascular, rendering immediate mechanical debulking high risk for significant hemorrhage. Consistent with PDT’s known mechanism and depth constraints, the smaller RLL superior segment lesion achieved complete endobronchial response, whereas the larger LLL lesion achieved partial but clinically meaningful response with improved airway patency and minimal bleeding, facilitating subsequent staged airway toileting and adjunct cryotherapy during follow-up bronchoscopies.

A major practical advantage of PDT is that its light source is non-thermal, which avoids airway-fire risk and can be especially helpful in patients who require higher inspired oxygen concentrations than permitted for thermal techniques (1,7,8). Conversely, PDT-specific risks include prolonged photosensitivity and, within days of treatment, airway edema, secretions, and necrotic slough that may precipitate transient airway compromise, reinforcing the need for planned debridement bronchoscopy in appropriate patients (6,7,12,23). Tumors that abut or invade major vascular structures are typically approached with extreme caution in therapeutic bronchoscopy; this consideration is particularly relevant in hypervascular endobronchial metastases where delayed hemorrhage, while uncommon, is clinically consequential (1,7,23). The presence of airway stents can complicate light delivery; while experimental and early clinical feasibility work suggests that PDT through transparent silicone stents is technically possible under defined conditions, broader clinical validation remains limited (30).

Implications and actions needed

This case highlights a need for better evidence to guide PDT use in non-lung-primary endobronchial metastases, including metastatic PTC. Prior reports of PDT for metastatic endobronchial lesions are limited and largely consist of case reports and small series across select primaries (19,20). Given the rarity and heterogeneity of these presentations, multicenter collaboration will likely be required to refine patient selection, dosing and retreatment strategies, and outcome reporting, particularly in hypervascular tumors where bleeding risk strongly influences modality choice. The feasibility and value of multicenter PDT collaboration is demonstrated in lower-airway recurrent respiratory papillomatosis, where pooled multicenter experience supported safety and effectiveness and emphasized multimodal integration (23). In parallel, population-level observational analyses in advanced NSCLC with airway obstruction suggest that incorporating PDT alongside systemic therapy pathways may be associated with outcomes comparable to standard chemoradiation cohorts, while non-PDT local ablation strategies in similar datasets have shown less favorable associations (28,29). These observations support the hypothesis that durable airway patency and maintenance therapies may facilitate delivery of systemic treatment in advanced disease.

Conclusions

Staged bronchoscopic PDT with protocolized revision bronchoscopy and adjunct cryotherapy provided effective airway palliation and local endobronchial control for hypervascular metastatic PTC causing lobar obstruction, without major bleeding or airway compromise. PDT may be considered as part of a multidisciplinary, longitudinal bronchoscopic strategy when immediate debulking is high risk.

Acknowledgments

The authors would like to thank the oncology team, interventional pulmonology bronchoscopy suite nursing and respiratory therapy, and pathology staff at The Ohio State University Wexner Medical Center for their procedural support in the care of this patient.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://atm.amegroups.com/article/view/10.21037/atm-2026-0057/rc

Peer Review File: Available at https://atm.amegroups.com/article/view/10.21037/atm-2026-0057/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-2026-0057/coif). A.E.R. serves as an unpaid editorial board member of Annals of Translational Medicine from February 2026 to December 2027. B.K. reports grants from RayzeBio, Merck, and Eisai, and consulting fees from Exelixis. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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