[Morphology of nasopharyngeal fibroma (author's transl)].

Light and electron microscopic investigations of four cases with juvenile nasopharyngeal fibroma revealed the characteristic structures like a fibrous stroma, and inclination to hyalinisation and formation of scar like tissue, a lacunar thin walled vascular component, a high amount of mast cells, and of fibroblasts with different nuclear bodies and particles. The well known electron dense nuclear inclusions were subdivided into three groups of size. The tumor cell nuclei also contained five different types of more or less complex bodies with spherical shape. In addition to the earlier described ultrastructural properties of the tumor the nuclei of the tumorous fibroblasts were found to contain virus like particles measuring 40 to 55 nm in diameter. These particles were aggregated to groups; they were different from chromatin condensations and from perichromatin granules. The structure and size of the smaller particles was not comparable to that of the electron dense nuclear inclusions regarded as pathognomonic in the nasopharynegal fibroma.