[Electron microscopic examination on cytogenesis of juvenile nasopharyngeal angiofibromas (author's transl)].

After the electron miscroscopic examination of tissue samples of juvenile nasopharyngeal angiofibromas obtained from 9 male patients ranging in their age from 7-24 years the problems of cytogenesis and classification are discussed. Besides it is tried to correlate particular morphological findings to certain clinical phenomenons. The vascular component of juvenile nasopharyngeal angiofibromas shows a clear proliferation of the vascular wall cells. Particularly, proliferating pericytes, cells withous peculiar characteristics ("undifferentiated" cells) and cells in various stages of differentiation are to be emphasized. Obviously, vascular wall cells emigrate into the surrounding tissue and transform themselves into small fibroblasts. The second component of juvenil nasopharyngeal angiofibromas is represented by stromal fibroblasts with several cytological variations. Only activated "classical" fibroblasts and fibroblasts with histocyte-like features reveal the nuclear pattern unique for these growths which is characterized by the combination of protrusions of nuclear membrane with formation of nuclear "blebs" and of dense intranuclear granules. Cells with these nuclear characteristics were considered as preexisting fibroblasts. Thus juvenile nasopharyngeal angiofibromas are formed by the proliferation of two tissue components, namely by the proliferation of vascular wall cells and stromal fibroblasts, and can be conceived as reactive hyperplasias. The swelling body-like and organoid appearance, cytological pecularities, characteristic topographic relations (localization and supplying vessesl) and the sex-dependent occurrence speak for a tumor-like hyperplasia of a rudimentary organ unknown till now.