Pulmonary sarcoidosis

More than a century after its discovery by Boeck, the cause of sarcoidosis remains unknown. However, recent research has revealed susceptibility genes on chromosome 5 and 6. The large US ACCESS study has identified potential triggers that suggest infectious or other environmental agents play a role in the genesis of the disease. Diagnosis still depends on clinical evaluation, chest radiography, lung function testing, measurement of serum angiotensin converting enzyme (ACE), tissue biopsy where indicated, and exclusion of other granulomatous disease. Treatment strategies have remained largely unchanged for two decades. No long-term systemic therapy is usually needed for the common presentation of Löfgrens syndrome (bilateral hilar adenopathy (BHL), erythema nodosum (EN), transient iritis). Corticosteroids remain the drugs of first choice and are effective in suppressing tissue inflammation. They are mandatory for all patients presenting with pulmonary infiltrates and impaired lung function, or for those with critical extra-thoracic organ dysfunction or hypercalcaemia. However, in a number of cases, adverse effects are sufficient to prompt the introduction of steroid-sparing immunosuppressive agents such as methotrexate, azathioprine or hydroxychloroquine. Anti-TNFα agents, such as infliximab, have proved disappointing in pulmonary sarcoidosis but may have a useful niche role in some cases with refractory extra-pulmonary disease as a supplement to other therapies. Lung transplantation is successful in end-stage fibrotic disease, but sarcoid granulomas may emerge in the allograft and fungal contamination of fibro-bullous cavities may confer increased post-operative risk of systemic infection.