Ultrastructural cytochemistry of intranuclear dense granules in nasopharyngeal angiofibroma

Electron-dense round granules (ING) were found in the nuclei of fibroblastic cells of all the tumors examined by us (6 cases) and diagnosed clinically and histologically as nasopharyngeal angiofibroma (NPAF). The ING were consistently associated with this tumor and can be regarded as pathognomonic of NPAF. We studied at the ultrastructural level the composition of these particles using various cytochemical techniques. Enzymatic digestions carried out on thin sections as well as staining methods preferential or specific for nucleoproteins have revealed that ING represent tightly bound RNA-protein complexes and do not contain DNA. There are no data available that the ING takes part in the metabolism of NPAF fibroblastic cells.