[Oncocytic paraganglioma of the carotid body]

One case of benign oncocytic paraganglioma which had originated from the non-chromaffin cells of the carotid body in a woman, 66 years of age, is described in this paper. The microscopic pattern of the tumor consisted mainly of large, round, eosinophilic cells arranged in solid nests and sheets. Pale rather than eosinophilic cells of polygonal shape were predominant in the peripheral areas. Ultrastructural analysis revealed the presence of three cell types: oncocytes, cells with electron-dense granules, 150 to 200 nm in size, and transitional forms between these two. Possible development of oncocytes from APUD cells is discussed.