Sarcoidosis: Review of Diagnosis and Treatment

Abstract

Background: Sarcoidosis is a systemic heterogenous granulomatous disease of unknown etiology that results in inflammation of pulmonary and extrapulmonary sites. In a minority of patients it can result in fibrosis and permanent organ damage. Most commonly mentioned causes of sarcoidosis include atypical mycobacterium, proprionobacterium and inorganic dusts. Once exposed to an organic or inorganic, an Antigen Presenting Cell (APC) prepares and presents the antigen to a T cell and its respective HLA locus. In a susceptible person, this provides cytokine production, differentiation into T helper cells and provokes an immune response that in its early stages is allayed by corticosteroids or other immunomodulatory agents. In the majority of patients appropriate immunomodulatory therapy will control the disease and prevent progression. However, in 20-25 % the disease can progress and lead to organ damage or compromise and fibrosis. Sarcoidosis is a relatively common disease with an incidence of 2.3-17.8 per 100,000. It is 2-4 times more common in African Americans than Caucasian Americans with the mean age of onset of 45-50 years of age. Unlike autoimmune rheumatic disease the disease occurs almost as commonly in men than women. Sources: A Medline, Pub Med review from 1999-2021. Spectrum of Disease: Sarcoidosis occurs in 90-98 % of patients during the course of their disease. Eleven to twenty two percent of patients have involvement of either the liver, Skin, ocular (uveitis), Lymph nodes and spleen. The upper airway, liver, CNS and heart comprise <10% of cases each and the bone, joints/ muscle, and hypercalcemia < 5%. Diagnosis: With the exception of Lofgren’s and Heerfordt’syndromes the presence of non-caseating/necrotizing granuloma must be present on biopsy of at least one site and mycobacterial or fungal infections or malignancy must be ruled out. If clinically suspicious, Skin and peripheral lymph nodes are the least invasive areas for biopsy and if hilar or mediastinal nodes are suggestive, an EBUS approach is recommended. In organs such as the heart and CNS where biopsy is either insensitive or invasive, a Cardiologist and Neurologist in concert with a Rheumatologist can make a probable diagnosis based on clinical presentation, PET or MRI and exclusion of alternative diseases.