Crystals in a jugulotympanic paraganglioma.

The morphologic features of a jugulotympanic paraganglioma are reported. The tumor showed the usual histology of paragangliomas. No sustentacular cells were identified. In the tumorous chief cells there were typical neurosecretory dense-core granules 60-180 nm in diameter. Granules averaging 400 nm in diameter were also observed, sometimes with a regular rhomboid core or crystallized content. Rhomboid crystals were seen in the cytoplasm in membrane-bound spaces and in telolysosomes. The crystals had a substructure consisting of alternating light and dark lines with a periodocity of 5-10 nm. Such crystals had not been reported previously in paragangliomas. The possible origin of the crystals is discussed.