[Growth patterns of juvenile nasopharyngeal fibromas. A histological analysis on the basis of 40 cases].

Juvenile nasopharyngeal angiofibroma is a unique process characterized by an exclusive localization in the nasopharynx of young male patients, and a typical histological pattern composed of angiomatous and fibrous structures. Forty tumors of patients 7 to 25 years of age were investigated. The tumors showed a characteristic zonal organization. Apart from the superficial epithelium the lesions can be subdivided into a subepithelial myxoid-fibrous zone followed by a proliferative capillary fibroblastic cambium layer. In the latter, either the capillary component or the fibroblasts can prevail. The main part is composed of sinus-like vascular channels and a fibrous component. The gaping vascular channels differing in caliber are lined by a single layer of epithelium and surrounded by single or mostly an incomplete rim of smooth muscle cells. Elastic fibres are always lacking. The fibrous component exhibits a changing cellularity and fibre content. Myxoid foci can be encountered, often associated with a pleomorphic cell pattern. Generally, however, fibre structures and foci or large areas of hyalinization predominant in direction to the central parts. In older lesions the fibrous tissue is prevailing. The capillary fibroblastic cambium zone disappears and areas of hyalinization are enlarged. In five cases relapses showing the same structural features were observed. Juvenile nasopharyngeal angiofibromas are discussed as a specific but non-autonomous proliferating growth process which is characterized by 1. specific age and sex incidence, probably in relation to hormones, 2. typical histological pattern and cytological criteria, including local infiltration of the surrounding musculature and bones, 3. origin in the same region corresponding to the membrana buccopharyngea and constant blood supply by the arteria maxillaris interna, or its end artery, the arteria sphenopalatina. According to the corpus cavernosum-like structures, comparable to erectile tissue, the nasogenital relations are discussed. Juvenile nasopharyngeal angiofibromas are defined as a specific clinicopathological entity.