title: Thin-walled ring shadows in early pulmonary sarcoidosis.
abstract: The appearance of ring shadows on the chest radiograph of patients with sarcoidosis is usually associated with generalised, irreversible pulmonary fibrosis. We report three patients in whom thin-walled ring shadows appeared early in the disease. These ring shadows occurred in areas of pre-existing lung shadowing and in two patients they disappeared with corticosteroid therapy over a period of 1-2 years. We postulate that these early sarcoid ring shadows may be caused by a combination of central necrosis of areas of coalescent granulomas and a check-valve mechanism beyond partial obstruction of airways by endobronchial sarcoidosis.
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008297:Male; D012507:Sarcoidosis / Q000000981:diagnostic imaging*; D014056:Tomography, X-Ray; D014057:Tomography, X-Ray Computed