Endogenous and exogenous material within granulomas. A, Asteroid body (endogenous) in sarcoidosis. B, Crystalline inclusion (endogenous) in sarcoidosis (the inclusion is birefringent [inset]). C, Needle-shaped, crystalline inclusion (endogenous) in hypersensitivity pneumonitis. D, Cholesterol cleft (endogenous) in hypersensitivity pneumonitis. E, Two asteroid bodies (endogenous) in talc granulomatosis. Exogenous material is also present (arrow). F, Microcrystalline cellulose (exogenous) in “talc” granulomatosis (birefringence [inset]). G, Vegetable particles (exogenous) in aspiration pneumonia. Legumes of various kinds (“lentils”) share this morphology. H, Degenerated vegetable material (exogenous) surrounded by multinucleated giant cells. Same case as G. Such structures can be more difficult to recognize than intact vegetable particles (hematoxylin-eosin, original magnifications ×400 [A–H]; hematoxylin-eosin, polarized light, original magnifications ×400 [insets B and F]).