Answer: Juvenile nasal angiofibroma

Histology: This lesion is a polypoid one with an ulcerated surface and secondary reactive changes. The center of the lesion demonstrates a fibrous stroma with somewhat haphazard, wavy collagen and irregular slit-like vascular spaces that lack a well-developed muscular, pericytic, or elastic layer. The stromal cells within the lesion are myofibroblastic, having a stellate and sometimes a ganglion cell-like appearance with amphophilic cytoplasm. Mitoses are extremely rare.

Discussion: A fibromatosis would have an infiltrative pattern, and should demonstrate fascicular growth. Fibromatoses usually do not present as polyps within the nasal cavity. A solitary fibrous tumor would feature abundant collagen and bland fibroblastic cells, but typically demonstrates more fascicular growth patterns, and alternations in cellularity. A lobular capillary hemangioma should show central feeder vessels surrounded by small capillaries which branch off in an orderly fashion.

Juvenile nasal angiofibroma (JNA) typically presents in adolescent males, which makes sense because the stromal cells have been demonstrated to have testosterone receptors. The typical location is high within the lateral nasopharynx or posterior nasal cavity. JNA are highly vascular, so they are typically embolized pre-operatively. JNA are associated with familial adenomatous polyposis (FAP), in that they occur 25 times as frequently in FAP patients than in age-matched controls. JNAs are typically benign lesions, but can be locally aggressive and erode bone. Interestingly, sporadic JNA often demonstrate activating â-catenin mutations, which correlates with their association with FAP. It appears, therefore, that the APC/â-catenin pathway is inactivated in most of JNA.