A Rapid Qualitative Review of Sarcoidosis: Clinical Manifestations, Immunopathogenesis, Diagnosis and Treatment

Sarcoidosis is a worldwide inflammatory disorder of unknown etiology that is characterized by the formation of non-caseating immune granulomas in involved organs, most commonly in the lungs and eyes. Although clinical manifestations of sarcoidosis depend on the organs involved, the most common symptoms include fatigue, fever, weight loss, eye pain, dyspnea, and chest pain. Sarcoidosis usually undergoes spontaneous regression, yet its chronic form progressively threatens the mvolved organs through the induction of fibrotic damage. Despite decades of medical research, the etiology of sarcoidosis still remains unclear. Nevertheless, a combination of contributors, including genetic factors, environmental exposures, and microbial agents, is believed to trigger the inflammatory state observed in this disease. Furthermore, a highly polarized Th1 and Th17 response with diminished immunomodulatory mechanisms constitute the most significant immunological event associated with this disorder. Indeed, sarcoid granulomas, which consist of highly activated antigen-presenting cells (APCs) and lymphocytes, maintain a robust specialized niche to facilitate antigen presentation and exaggerated immune responses. Both the unknown etiology and multisystem nature of the disease have hampered the development of specific therapeutics and definitive diagnostic assays for sarcoidosis. Consequently, its diagnosis and treatment still represent a challenging task for clinicians. In this article, we aim to summarize contemporary findings of sarcoidosis and its etiology, pathogenesis, and treatment.