Abstract Introduction Rheumatoid pneumoconiosis (Caplan syndrome) is a rare overlap syndrome that was first described in the early 1950s. It is characterized by coal, asbestos, or silica-related pneumoconiosis, classically with peripheral-predominant pulmonary nodules, and concurrent clinical features of rheumatoid arthritis. Here we describe the clinical, radiographic, and histopathologic findings of a patient with occupational silica exposure who was ultimately diagnosed with rheumatoid pneumoconiosis. Case Description A 56-year-old male with a history of prediabetes presented to the Emergency Department for progressive arthralgias, myalgias, and fatigue over the past two years. He reported 25 pounds of weight loss, night sweats, and cough productive of clear sputum over the preceding 3-6 months. He worked for a granite countertop company for 25 years with roles including granite and quartz cutting and grinding. Vital signs demonstrated an oxygen saturation of 91% on 1L oxygen. Physical exam was notable for right knee and left elbow swelling and tenderness without associated erythema. Pertinent labs included an erythrocyte sedimentation rate of 57 and C-reactive protein of 93.1. Chest computed tomography demonstrated diffuse intralobular septal thickening and innumerable bilateral lung nodules in a peri-lymphatic distribution with mediastinal and hilar lymphadenopathy. A bronchoscopy with bronchoalveolar lavage revealed 51% monocytes, no growth on cultures, and negative cytology. Transbronchial lung biopsy showed nodular lesions of concentrically arranged collagen and birefringent material consistent with silica (Figure 1). Extensive infectious and autoimmune workup was completed and notable for a rheumatoid factor of 56 and anti-cyclic citrullinated peptide antibody (anti-CCP Ab) 200. He was diagnosed with rheumatoid arthritis and given radiographic, histopathologic, and clinical history consistent with silica-related pneumoconiosis, he was diagnosed with rheumatoid pneumoconiosis (Caplan syndrome). The patient was counseled on complete avoidance of silica exposure and started on corticosteroids, methotrexate, and rituximab with rheumatology and pulmonology follow up. Figure 1. Partial polarization reveals weakly birefringent silica and strongly birefringent silicate particles in a background of dense collagen and anthracotic particles. Discussion Rheumatoid pneumoconiosis is a rare overlap syndrome with limited epidemiological data and unclear pathophysiology. Originally attributed to coal dust exposure, it is also described in patients with inorganic dust exposure from silica and asbestos industries. While the exact relationship is not clarified, there are growing links between silicosis and autoimmune diseases other than rheumatoid arthritis, including systemic sclerosis, dermatomyositis and sarcoidosis. Although there is no specific therapy, management is focused on eliminating inorganic dust exposure and treating rheumatoid arthritis with guideline-directed therapies. This abstract is funded by: None
Rewerts et al. (Fri,) studied this question.