An asteroid body is a microscopic finding seen within the giant cells of granulomas in diseases such as sarcoidosis and foreign-body giant cell reactions.[1]
There is controversy about their composition. Traditionally, they were thought to be cytoskeletal elements and to consist primarily of vimentin.[2] However, more recent research suggested that that was incorrect and that they may be composed of lipids arranged into bilayer membranes.[3]
They were also once thought to be related to centrioles,[4] an organelle involved in cell division in eukaryotes.