Sarcoidosis: a state of the art review from the Thoracic Society of Australia and New Zealand

Summary

• Sarcoidosis is a systemic disease of unknown aetiology, characterised by non-caseating granulomatous inflammation. It most commonly manifests in the lungs and intrathoracic lymph nodes but can affect any organ.
• This summary of an educational resource provided by the Thoracic Society of Australia and New Zealand outlines the current understanding of sarcoidosis and highlights the need for further research.
• Our knowledge of the aetiology and immunopathogenesis of sarcoidosis remains incomplete.
• The enigma of sarcoidosis lies in its immunological paradox of type 1 T helper cell-dominated local inflammation co-existing with T regulatory-induced peripheral anergy.
• Although specific aetiological agents have not been identified, mounting evidence suggests that environmental and microbial antigens may trigger sarcoidosis.
• Genome-wide association studies have identified candidate genes conferring susceptibility and gene expression analyses have provided insights into cytokine dysregulation leading to inflammation.
• Sarcoidosis remains a diagnosis of exclusion based on histological evidence of non-caseating granulomas with compatible clinical and radiological findings.
• In recent years, endobronchial ultrasound-guided transbronchial needle aspiration of mediastinal lymph nodes has facilitated the diagnosis, and whole body positron emission tomography scanning has improved localisation of disease.
• No single biomarker is adequately sensitive and specific for detecting and monitoring disease activity.
• Most patients do not require treatment; when indicated, corticosteroids remain the initial standard of care, despite their adverse side effect profile.
• Other drugs with fewer side effects may be a better long term choice (eg, methotrexate, hydroxychloroquine, azathioprine, mycophenolate), while tumour necrosis factor-α inhibitors are a treatment option for patients with refractory disease.