Focus on Sarcoidosis
- The most common causes of disability and death from sarcoidosis are directly or indirectly related to complications of fibrotic lung disease . Fibrosis develops in up to 20% of pulmonary sarcoidosis patients [2,3] and may result in end-stage parenchymal lung disease . Fibrotic pulmonary sarcoidosis is associated with distortion of airways leading to airflow obstruction, bronchiectasis, and increased episodes of clinical worsening that are often related to pulmonary infections [4–7]. Sarcoidosis associated pulmonary hypertension is caused by a variety of mechanisms, but the most common of these is distortion of the pulmonary vasculature from fibrosis [8,9].
- Sarcoidosis is a multi-system disease of unknown cause characterized by noncaseating granulomatous inflammation that results in symptoms and organ dysfunction due to persistent inflammation and fibrosis. It predominately affects the lungs in over 90% of patients, but can injure any organ in the body. Sarcoidosis can be a life-threatening disease, particularly in those with pulmonary fibrosis, pulmonary hypertension, or cardiac involvement [1,2]. Opportunistic infections may also play a role in mortality in patients on immunosuppression [2,3].
- The widespread perception that sarcoidosis is essentially a benign disease has undoubtedly contributed to a lack of investment in sarcoidosis-related public health and research initiatives. Respiratory clinicians managing both pulmonary sarcoidosis and idiopathic pulmonary fibrosis may be especially likely to subscribe to this view. Unlike most other forms of fibrotic lung disease, pulmonary sarcoidosis stabilizes with time, with or without therapy, in the majority of patients. Sarcoidosis patients with major cardiac or neurologic involvement are often managed by sub-specialists and may be under-represented in general sarcoidosis cohorts.
- The diffuse parenchymal lung diseases (DPLDs), often collectively referred to as the interstitial lung diseases (ILDs), are a heterogeneous group of disorders that are classified together because of similar clinical, radiographic, physiologic, or pathologic manifestations . Universal features of the DPLDs include cellular proliferation, inflammation and/or fibrosis within the alveolar wall . Architectural distortion of the airways and alveoli is also frequently present. The DPLDs are categorized into those that are associated with known causes and those that are idiopathic.
- Cardiac sarcoidosis is a potentially life-threatening form of the disease. Although most sarcoidosis-related deaths result from lung involvement, most of these deaths occur after years of the slow development of lung fibrosis from granulomatous inflammation [1,2]. Contrary to pulmonary sarcoidosis, cardiac sarcoidosis may cause life-threatening events and severe organ dysfunction relatively quickly because of myocardial granulomas deposited in unfortunate locations. Furthermore, myocardial sarcoid granulomas tend to progress relatively quickly to scar  that does not respond to anti-granulomatous therapy and is permanent.
- Most clinicians agree that corticosteroids are the first choice for treatment for symptomatic pulmonary sarcoidosis [1,2]. Prednisone is one of the most commonly used corticosteroids, with the usual initial dose being 20–40 mg daily [3,4]. However, the specific dose and rationale for such a dose is unclear. Early studies of corticosteroids were associated with quite variable doses and duration of therapy. In some studies, 60 mg for one month and then slowly tapered for more than a year  while others gave 15 mg for three months total .
- Sarcoidosis remains an enigmatic disease. Its cause is unknown, the indications for treatment are often unclear, and its natural history is variable. An additional important enigmatic issue that has hampered clinical sarcoidosis research is the failure to develop reliable and universally accepted clinical endpoints.
- With this editorial, my Editorial Board Members and I launch the maiden voyage of Respiratory Medicine: Focus on Sarcoidosis, a companion journal of Respiratory Medicine. The journal's scope will encompass the etiology, immunopathogenesis, diagnosis, clinical manifestations, natural history, treatment, and outcomes of sarcoidosis. The journal will devote a significant amount of space to extrapulmonary sarcoidosis, in addition to pulmonary sarcoidosis.