Nasopharyngeal Angiofibroma

Epidemiology:

• Adolescent males (almost exclusively)
• 10-25y

Common sites:

• distinctive location, arising from an area of erectile-like fibrovascular stroma
• posterolateral wall of the roof of the nose
• where the sphenoidal process of the palatine bone meets the horizontal ala of the vomer and the root of the pterygoid process of the sphenoid bone

Gross features:

• polypoid mass

Histologic features:

• intricate mixture of blood vessels and fibrous stroma
• vessels:
• range from capillary to venous size
• “erectile tissue” appearance
• plump endothelial cells in small capillary-like vessels at “growing edge” of lesion
• large vessels have irregular or incomplete smooth muscle coat and lack elastic fibers
• stroma:
• may be loose / edematous with stellate fibroblasts and numerous mast cells
• may be dense, acellular, highly collagenized (diagnostic)

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Androgen receptors (stromal and endothelial)	75%

Molecular features:

Other features:

• tendency to bleed profusely on manipulation
• EM – distinctive electron-dense granules composed of tightly bound RNA protein complexes in the nuclei of the proliferating cells
• Some large angiofibromas regress after puberty, especially after (incomplete) surgery or radiation