B57-17 Lymph Node-Dominant Occupational Pneumoconiosis (Silicosis): A Rare Presentation Mimicking Sarcoidosis and Malignancy

Abstract Introduction Silicosis is an irreversible fibrotic lung disease caused by chronic exposure to crystalline silica. While parenchymal nodules classically predominate, some cases present with dominant mediastinal/hilar lymph node involvement. This phenotype may closely resemble sarcoidosis, lymphoma, or tuberculosis, leading to diagnostic uncertainty and unnecessary invasive procedures. We report an illustrative case of lymph node-dominant silicosis. Case Description A 54-year-old male presented with progressive exertional dyspnea, intermittent cough, and whitish sputum. He had no previous diagnosis of lung/systemic disease. He was an active smoker with a 39 pack-year history. His occupational background revealed approximately twenty years of work in stone quarries, involving dynamite blasting and excavation under heavy dust exposure with poor respiratory protection. For the past twelve years he had worked as a night watchman, without further mineral dust exposure. No environmental asbestos exposure was reported.The initial chest radiograph from 2024 (Figure-1A) showed mild bilateral reticulonodular opacities without distinct nodules. Follow-up radiographs(Figure-1B-C) and thoracic CT scans(Figure-1D) mid-2025 revealed multiple mediastinal and hilar lymph nodes, the largest measuring approximately 20 × 11 mm, predominantly at the right lower paratracheal and subcarinal regions, along with minimal centrilobular emphysema and pleural traction lines. The radiologic pattern raised the suspicion of sarcoidosis; prompting a FDG PET-CT.The PET-CT (Figure-1E) demonstrated multiple hypermetabolic lymph nodes in the paratracheal, subcarinal, aortopulmonary, and hilar regions with a SUVmax of 22.4. EBUS-TBNA from stations 4R and 7 showed lymphocytes and coarse anthracotic pigment without malignant cells or granulomas. Acid-fast staining and mycobacterial cultures were negative. Due to persistent diagnostic uncertainty, a repeat EBUS and subsequently mediastinoscopic biopsy were performed. Serum ACE was normal(28 U/L), and lab findings revealed secondary polycythemia likely related to hypoxemia and smoking. Histopathologic examination of mediastinoscopic specimens from stations 2R, 2L, 4L, and 4R revealed anthracotic lymph-node fragments with variable fibrosis; notably, station 4R contained a silicotic nodule with extensive anthracosis: on Masson’s trichrome at 20×, fibrotic areas stained blue (Figure-1F), and on H histopathology is decisive. Management: remove exposure, smoking cessation, pulmonary rehabilitation, structured follow-up. Public-health takeaway: strict dust control and effective respiratory protection. This abstract is funded by: None