A43-10 A Rare Case of Subpleural Small Cell Lung Cancer in a Patient With Usual Interstitial Pneumonia: Diagnostic and Palliative Challenges

Abstract Small cell lung cancer (SCLC) in patients with interstitial lung disease (ILD) of the usual interstitial pneumonia (UIP) pattern is extremely rare. Most lung cancers in UIP are non-small cell, predominantly squamous or adenocarcinoma. The coexistence of SCLC, UIP, and advanced heart failure (HF) poses unique diagnostic and therapeutic challenges, often limiting standard interventions. A 63-year-old male construction worker, with a 15-year history of chronic cigarette smoking and alcohol use, and known ischemic heart disease (post-percutaneous coronary intervention, ejection fraction 30%), presented with cough, expectoration, and exertional breathlessness for 20 days. On examination, diffuse Velcro-like crepitations were noted bilaterally. Pulmonary function tests (PFTs) revealed severe restrictive lung disease (forced vital capacity FVC 1.85 L pre, 1.92 L post; forced expiratory volume in one second FEV1 1.0 L pre, 1.57 L post). Chest radiograph demonstrated fine reticulations in both lung fields. Contrast-enhanced computed tomography (CECT) revealed a lobulated, hyper-enhancing left lower lobe lesion with pleural involvement, underlying UIP fibrosis, traction bronchiectasis, and a 13 × 4.9 × 5.4 cm mediastinal mass encasing major vessels and compressing bronchi. Positron emission tomography-computed tomography (PET-CT) confirmed metabolically active mediastinal and left lower lobe lesions, extensive lymphadenopathy, and metastases to liver, bone, and cervical nodes. CT-guided biopsy from the subpleural lesion confirmed SCLC (Synaptophysin+, Chromogranin+, thyroid transcription factor-1 TTF-1+), Ki-67 70%. Due to liver dysfunction, chemotherapy was not feasible; pirfenidone was interrupted for hepatotoxicity. The patient was managed with guideline-directed medical therapy for HF and early palliative care focusing on symptom relief and quality of life, but he ultimately deteriorated from progressive liver metastases. SCLC in UIP is rarely reported. Literature estimates lung cancer prevalence in UIP at 3-20%, mostly non-small cell. Subpleural SCLC with pleural or diaphragmatic involvement, extensive mediastinal invasion, and multi-organ metastases is exceptionally uncommon. Management is constrained by high risk of acute ILD exacerbation with chemotherapy or radiotherapy, further complicated by HF. This case highlights the importance of early multidisciplinary involvement, balancing oncologic treatment with symptom control, and the pivotal role of palliative care in patients with limited therapeutic options. The triad of subpleural SCLC, UIP, and HF represents a rare and complex clinical scenario. This case underscores diagnostic challenges, aggressive disease behavior, and the value of early palliative interventions, contributing to the sparse literature on SCLC in fibrotic lungs and offering practical insights for clinicians managing high-risk patients. This abstract is funded by: None