[Caplan's syndrome: rarely presenting as <<pulmorenal>> syndrome].
A 59-year-old man complained about having dry cough for months and a recent sudden onset of minor hemoptoe, asymmetric arthritis, myalgia as well as lack of appetite. He presented an occupational history of 12-year exposure to an organic dust as uranium miner in German Democratic Republic followed by 21 years as heavy construction worker in Germany and in Switzerland. Laboratory work-up tested positive for microhematuria and anti-neutrophilic cytoplasmic antibodies (ANCA). Chest X-rays and CT scan showed bilaterally scattered nodules. Thoracoscopic wedge resection was performed, histopathological analysis revealed granuloma with central necrotic area containing black coal dust and silica depositions surrounded by histiocytes. The pulmonary opacities on X-ray and the typical histology in the light of significant dust exposure allow the diagnosis of a Caplan's syndrome. The symptoms improved rapidly under steroid therapy. Further investigations revealed a clear renal cell carcinoma as a cause for the persistent microhematuria. Rheumatoid arthritis, pulmonary nodules and history of prolonged dust exposure are classical findings that define Caplan's syndrome. These patients present with different immunological phenomena - in our case ANCA-positivity without vasculitis. Interestingly, the renal cell carcinoma which led to the "pulmorenal" syndrome in our patient is another health problem overrepresented in uranium mine workers.