True about pulmonary sarcoidosis

Sarcoidosis is a granulomatous disorder of unknown etiology characterised by the presence of non-caseating granulomas.The use of the lymphocyte markers CD4 & CD8 can be used to determine the CD4/CD8 ratio of increased lymphocytes in the BAL fluid.A ratio of >3.5 is strongly suppoive of Sarcoidosis.Schaumann and Asteroid bodies can be seen,but they are non-pathognomic.Asteroid bodies are stellate inclusions with numerous rays radiating from a central core.They are seen in granulomas of Sarcoidosis,tuberculosis,leprosy,foreign body type,etc.Schaumann bodies are large concentric calcification often containing refractile calcium oxalate crystals.They are seen in Sarcoidosis,Beryllosis,hypersensitivity pneumonitis . Reference:Harrison' s Medicine,Davidson's Medicine,22nd edition,page no:710,711.