ABSTRACT
Pulmonary adenoid cystic carcinoma (PACC) is a rare salivary gland-type malignancy of the tracheobronchial tree, accounting for 0.04%–0.2% of primary lung cancers. It may cause severe malignant airway obstruction (SMAO), necessitating urgent intervention. Surgical resection remains the primary treatment, but inoperability or patient preference may require alternative strategies. We report a case of a 57-year-old non-smoking female with PACC-SMAO who presented with total left lung collapse due to left main bronchus (LMB) involvement. She declined surgery and underwent bronchoscopic dual debulking combining electrocautery snaring with repeated intratumoural para-toluenesulfonamide (PTS) injections. The intervention safely reduced tumour burden, restored airway patency, and significantly improved clinical and radiological outcomes without adverse events. Our case underscores PTS as a promising adjunct therapy for inoperable PACC-SMAO, warranting further investigation into its long-term efficacy and optimal dosing. This innovative approach may significantly redefine palliative care options.
1 Introduction
Pulmonary adenoid cystic carcinoma (PACC), historically known as ‘cylindroma’, is a rare salivary gland tumour arising from the tracheobronchial submucosal glands, accounting for only 0.04%–0.2% of all primary lung malignancies tumours [1]. It predominantly affects the 40–60 age group. PACC varies in presentations, from asymptomatic to symptomatic, such as cough, dyspnoea, wheezing, haemoptysis, and obstructive pneumonia. It is often undetectable on standard chest radiograph, rendering computed tomography (CT) essential for assessing tumour location, extent, invasion, and intrapulmonary metastases.
Surgical resection remains the primary therapy for PACC. Endoscopic interventions, radiotherapy, and chemotherapy are options for palliative treatment in patients who are unsuitable or unwilling to undergo surgery. Emerging targeted therapies show promise by inhibiting pathways such as the myeloblastosis (MYB) proto-oncogene, epidermal growth factor receptor (EGFR) mutation, and vascular endothelial growth factor receptor (VEGFR), while immune checkpoint pathways like programmed death-ligand 1 (PD-L1) show low response rates.
Intratumoural therapy offers enhanced bioavailability, remodelling the tumour microenvironment and simultaneously reducing systemic and immune-related adverse effects [2]. Tumouricidal agents such as ethanol absolute, cisplatin and 5-fluorouracil have been utilised in lung cancer treatment [3]. Para-toluenesulfonamide (PTS), a low-molecular-weight hydrophobic compound, has shown tumouricidal effects with efficacy verified in breast, liver, head and neck cancers and non-small cell lung cancer with severe malignant airway obstruction (NSCLC-SMAO). Intratumoural PTS injection increases forced expiratory volume in 1 s (FEV1), enhances aeration and extends median survival. This therapeutic benefit has also been observed in PACC with SMAO (PACC-SMAO) [4].
We describe a case of PACC-SMAO successfully managed with bronchoscopic dual debulking—mechanical debulking via electrocautery snaring and chemical debulking with intratumoural PTS injection, leading to significant clinical and radiological improvement.