CRA21 WHEN SILICA CLOUDS THE DIAGNOSIS: A TUBERCULOSIS MIMIC
Nor Safiqah Sharil1,2, Boon Hau Ng1, Rose Azzlinda Osman1, Hsueh Jing Low3, Nik Nuratiqah Nik Abeed1, Andrea Yu-Lin Ban1
1. Respiratory Unit, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia
2. Internal Medical Unit, Faculty of Medicine and Health Science, Universiti Sains Islam Malaysia, Nilai, Negeri Sembilan.
3. Department of Anesthesiology and Critical Care, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia.
Introduction
Silicosis is a chronic and progressive form of pneumoconiosis resulting from long-term inhalation of crystalline silica dust, typically linked to occupations such as mining, construction, and stone cutting. In areas where tuberculosis (TB) is endemic, the diagnosis of silicosis can be challenging due to its overlapping clinical and radiographic features with TB. We present a case of silicosis in a tile installer, highlighting the potential for diagnostic confusion.
Case report
A 63-year-old Chinese man with a 30 pack-year smoking history presented with chronic cough, exertional dyspnoea, and reduced exercise tolerance. Chest radiograph revealed bilateral diffuse miliary nodules and reticulonodular opacities. He had worked as a mosaic tile installer for over 30 years, with frequent exposure to construction dust and minimal respiratory protection. High-resolution CT of the thorax showed bilateral centrilobular nodules, tree-in-bud opacities, upper lobe coalescent nodules with focal consolidation where the features suggestive of silicosis, tuberculosis, or malignancy. Sputum AFB smears and TB PCR were negative. Bronchoscopy showed no endobronchial lesions, and BAL cultures, GeneXpert MTB/RIF, and cytology were also negative. Transbronchial lung biopsy demonstrated silicotic nodules with concentric fibrosis and chronic granulomatous inflammation without caseous necrosis, confirming a diagnosis of silicosis.
Discussion
This case highlights the diagnostic challenges of silicosis, particularly in TB-endemic regions where radiological overlap is common. Misdiagnosis can result in unnecessary TB treatment. Recognition of silica exposure in a non-traditional occupation, such as tile installation, was key to the correct diagnosis. Histopathological confirmation, alongside a thorough occupational history, avoided mismanagement. This case reinforces the need for clinicians to maintain a high index of suspicion for occupational lung disease, even in the absence of classic risk factors.