The nature of juvenile nasopharyngeal angiofibroma.

OBJECTIVE: The goal of this study was to investigate the nature of juvenile nasopharyngeal angiofibroma. STUDY
DESIGN: Twenty-five excised tumors were studied morphologically to confirm the histopathologic features of the tumor.
METHODS: Paraffin sections of all tumor specimens were stained with hematoxylin-eosin for elastic fiber, polyclonal antibody to factor VIII-related antigen and monoclonal antibodies to smooth muscle actin, estrogen receptor, and progesterone receptor. A quantitative assessment of the vascular component changes was also performed in 14 cases. Ultrathin sections of 5 tumors were studied electromicroscopically. Particular attention was paid to the progressive changes of both vascular and fibrous components as well as their mutual relationship.
RESULTS: (1) Beneath the endothelium of the vascular component, there was a thin layer of spindle cells; these cells had a positive reaction for smooth muscle actin, thus proving to be pericytes. (2) The actively proliferating site of the tumor was usually at the peripheral portion, with abundant vascular element lined by plump endothelial cells. (3) At the central and base locations, the growth of tumor tissue usually appeared to be in a relatively resting state. The vascular component decreased in amount as the extracellular collagenous fibers increased.
CONCLUSIONS: Because of the bicellular mixed composition of the vascular component and the tendency of synchronous maturation of both vascular and fibrous elements, it is suggested that juvenile nasopharyngeal angiofibroma is similar to most hemangiomas by nature and is likely a vascular hamartoma or a pathologic and reactive proliferation of vessels.