Light- and electron-microscopic studies on multinucleated giant cells in sarcoid granuloma: new aspects of asteroid and Schaumann bodies.

Ultrastructural studies using transmission, analytical, electron, and light microscopy were performed on epithelioid granulomata in 4 lymph nodes from a case of sarcoidosis, emphasizing the organization of asteroid and Schaumann bodies in multinucleated giant cells and the deposition of chemical elements. Serial sectioning at semithin level showed a single multinucleated giant cell can contain up to 4 asteroid and 1 Schaumann body. Microtubules and centrioles were not found in asteroid bodies, although a centriolar field was present in 1 giant cell close to the plasma membrane, completely unrelated to the asteroid body. In 1 asteroid body, tubulelike structures were observed in a focus showing filament dissociation. A principal ultrastructural finding is intimate envelopment of radiating filamentous arms of the asteroid body by myelinoid membranes, extensive forms of which are also present between the arms. Elemental analysis revealed a definite peak of calcium and a probable phosphorus peak in relation to the asteroid body and associated myelinoid membranes. Calcium and phosphorus with smaller quantities of aluminum and iron were found in Schaumann bodies. Our studies indicate that organization of the asteroid body is more complex than hitherto described, independent of the centriolar and microtubular systems. Evidence for the possible developmental pathway of the Schaumann body is provided by morphological changes within myelinoid figures intimately related to the asteroid body.