Juvenile Nasopharyngeal Angiofibroma

Juvenile nasopharyngeal angiofibroma arises in the
confluence of the posterolateral nasal wall and the
lateral nasopharynx and occurs almost exclusively in
males during adolescence. The tumour is sessile
or polypoid and is histologically benign,
but has a tendency to recur and is locally destructive,
causing pressure necrosis of adjacent soft tissue and
bone. It may occasionally extend into paranasal sinuses,
orbit and cranial fossae. It is composed of vascular and
fibrous elements in varying proportions. The vessels in
the superficial portions of the tumour are mainly gaping
capillaries that may become compressed with increasing
stromal fibrosis. Thick-walled vessels without
elastic membranes and with irregular, incomplete or
absent muscle coats and focal intimal thickenings are
usually present in the deeper portions of the tumour.
These vessels resemble those normally seen in the submucosa
of the nasal conchae. The vascular elements are
embedded in fibrous tissue, which varies in cellularity
and collagenisation. Stellate fibroblast-like cells are often
present close to the blood vessels. The fibroblastic
cells of nasopharyngeal angiofibroma are strongly
positive for testosterone receptors. Ultrastructurally,
the nuclei of angiofibroma contain characteristic
dense granules. Occasionally, the fibroblasts may
exhibit cytologic atypia, and some of these cells may
be multinucleated, but mitosis is rare. Mast cells may
be numerous. There may be focal thrombosis, haemorrhage
and chronic inflammatory reaction. With the
advent of preoperative selective embolisation, iatrogenic
emboli are increasingly encountered
in resected specimens.



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