Occult lung adenocarcinoma diagnosed by EBUS-TBNA after pneumothorax resolution in an RA-ILD patient with respiratory failure

Abstract

RA-ILD is a serious complication of RA. Patients are prone to spontaneous pneumothorax and have a higher risk of lung cancer.Given poor lung function and high risk of pneumothorax recurrence, conventional biopsy is challenging, making diagnosis difficult. A 67-year-old male with a history of smoking and well-controlled rheumatoid arthritis presented with chest tightness and pleuritic chest pain. On admission, he was found to have respiratory failure (PaO₂ 58.9mmHg). Chest CT revealed left-sided pneumothorax with interstitial lung disease.Following closed thoracic drainage, the pneumothorax resolved, which was confirmed by follow-up chest X-ray.But the persistence of the patient’s chest pain despite resolution of the pneumothorax prompted further investigation.CT pulmonary angiography identified a suspicious mass in the left lower lobe with adjacent rib destruction and mediastinal lymphadenopathy. Given the high risk of recurrent pneumothorax from percutaneous biopsy in a patient with recent pneumothorax and pre-existing respiratory failure, a multidisciplinary team recommended Endobronchial ultrasound-guided transbronchial needle aspiration(EBUS-TBNA) as a safer alternative. EBUS of enlarged mediastinal lymph nodes (stations 7 and 11L) confirmed poorly differentiated lung adenocarcinoma.The patient subsequently received first-line chemotherapy with pemetrexed, cisplatin, and bevacizumab, after which his condition gradually stabilized. Both pneumothorax and interstitial lung disease can mask an occult malignancy, underscoring the need for clinical vigilance. EBUS-TBNA is a safe and effective diagnostic option in such high-risk cases.