You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Sarcoidosis and explain in detail?
Sarcoidosis is a multisystem granulomatous disorder of unknown aetiology that is characterised by the presence of non-caseating granulomas . The condition is more frequentlydescribed in colder pas of nohern Europe .The tendency for sarcoid to present in the spring and summer has led to speculation about the role of infective agents, including mycobacteria, propionibacteria and viruses, but the cause remains elusive. Genetic susceptibility is suppoed by familial clustering; a range of class II HLA alleles confer protection from, or susceptibility to, the condition. Sarcoidosis occurs less frequently in smokers. It may be associated with common variable immunodeficiency .Bilateral hilar lymphadenopathy (BHL) is often seen in young women .Alternatively, BHL may be detected in an otherwise asymptomatic individual undergoing a chest X-ray for other purposes. Ref - Davidsons 23e p630