Answer: Juvenile nasopharyngeal angiofibroma

Histology: The lesion consists of a large polypoid mass lined by attenuated, benign sinonasal epithelium with associated subepithelial chronic inflammation. The underlying tissue is notable for prominent dilated, angular blood vessels some of which display thickened smooth muscle layers. The endothelial lining is bland with no cytologic atypia. The intervening stromal fibroblasts are spindled to stellate with minimal to no cytologic atypia. No mitotic activity, necrosis or anastomosing vascular channels are identified. Immunostains show the stromal cells to be positive for the androgen receptor and to have nuclear beta-catenin labeling.

Discussion: As the name implies, juvenile nasopharyngeal angiofibromas are highly vascular tumors (hence “angiofibroma”) that typically arise from the posterior/posterolateral roof of the nasal cavity (“nasopharyngeal”) in adolescent males (“juvenile.”) The clinical presentation of teenage male with frequent epistaxis and a mass protruding into the nasal cavity that bleeds easily upon palpation is classic. The lesions are hormonally responsive, as evidenced by positive stromal labeling for the androgen receptor (but not estrogen receptor) in the majority of cases, so they can regress after puberty and are rarely if ever seen in female patients. They are benign tumors but can be locally aggressive, and surgery is the treatment of choice. Of interest, juvenile nasopharyngeal angiofibromas occur more frequently in patients with familial adenomatous polyposis, and this led to the discovery that even sporadic juvenile nasopharyngeal angiofibromas have activating mutations in the APC gene and can show nuclear beta-catenin labeling.

Reference(s):
– Abraham SC, Montgomery EA, Giardiello FM, Wu TT. Frequent beta-catenin mutations in juvenile nasopharyngeal angiofibromas. Am J Pathol. 2001 Mar;158(3):1073-8.
– Stokes SM, Castle JT. Nasopharyngeal angiofibroma of the nasal cavity. Head Neck Pathol. 2010 Sep;4(3):210-3.