Sinonasal Angiofibroma: Understanding Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
July 14, 2026

Sinonasal angiofibroma is a noncancerous (benign) but locally invasive tumor that starts in the nasal cavity or the nasopharynx (the upper part of the throat behind the nose). It is also called juvenile angiofibroma or nasopharyngeal angiofibroma. This tumor occurs almost exclusively in adolescent boys and young men, and it is made up largely of blood vessels, which is why it tends to bleed easily. Although sinonasal angiofibroma does not spread to distant parts of the body, it can grow into, and damage nearby structures, so careful treatment is important. This article will help you understand the findings in your pathology report, what each term means, and why it matters for your care.

What causes sinonasal angiofibroma?

The exact cause of sinonasal angiofibroma is not fully understood, but most of these tumors have a change in a gene called CTNNB1, which leads to abnormal activity in the WNT signaling pathway. The tumor’s growth also appears to be driven by androgens (male hormones), which helps explain why it develops almost exclusively in adolescent boys and young men after puberty. People with an inherited condition called familial adenomatous polyposis (FAP), which causes many polyps to form in the large intestine and raises the risk of several cancers, have a higher chance of developing sinonasal angiofibroma. For this reason, a diagnosis of sinonasal angiofibroma sometimes leads the care team to consider testing for FAP.

What are the symptoms?

The most common symptoms of sinonasal angiofibroma are recurring nosebleeds and nasal congestion. Because the tumor is composed largely of blood vessels, nosebleeds can be frequent or heavy. Larger tumors that grow into surrounding structures may cause facial swelling or deformity, changes in or loss of vision, and pain.

How is the diagnosis made?

Sinonasal angiofibroma is often diagnosed differently from most other tumors. Because it contains so many blood vessels, taking a biopsy can cause severe bleeding, so a biopsy is frequently avoided. Instead, the diagnosis is often made using imaging studies such as CT, MRI, and angiography (a scan of the blood vessels), which show a characteristic appearance in a typical location in an adolescent boy or young man. The diagnosis is then confirmed by a pathologist who examines the tumor under the microscope after it has been surgically removed.

Under the microscope, sinonasal angiofibroma is made up of many irregular, variably sized blood vessels surrounded by supporting cells called fibroblasts. The fibroblasts may be described as bipolar (having two ends), or stellate (star-shaped), and occasional mitotic figures (dividing cells) may be seen. The connective tissue within the tumor is often described as collagenized or fibrotic. If a procedure called embolization (which blocks the blood vessels feeding the tumor to reduce bleeding) was performed before surgery, some blood vessels may contain foreign material, and there may be areas of necrosis (cell death).

To confirm the diagnosis, the pathologist may perform immunohistochemistry, a test that uses specially labeled antibodies to detect proteins in the tumor cells. In sinonasal angiofibroma, the tumor cells typically show nuclear beta-catenin and are positive for the androgen receptor, while markers such as S100, SOX10, and STAT6 are negative. This pattern helps distinguish sinonasal angiofibroma from other tumors that can occur in this area.

Staging

Sinonasal angiofibroma is not staged using the TNM system used for cancers, because it is a benign tumor. Instead, doctors describe how far it has spread using imaging-based staging systems (such as the Radkowski or Fisch systems), which assess how deeply the tumor extends into the nasal cavity, sinuses, and nearby structures. These systems come from imaging rather than from the pathology report, and they mainly help the surgical team plan the best approach to remove the tumor. In general, tumors that remain within the nasal cavity and nasopharynx are easier to remove completely than those that have grown into the sinuses, the eye socket, or the base of the skull.

Surgical margins

A surgical margin is the edge of the tissue that the surgeon cuts through when removing the tumor. Margins are described in your report only after the entire tumor has been removed, not after a biopsy. Because sinonasal angiofibroma is a benign tumor, the report may simply state that the tumor was completely removed or that the margins are negative.

Negative margin — No tumor cells are present at the cut edge of the tissue. This suggests the tumor was completely removed.
Positive margin — Tumor cells are present at the cut edge. This is associated with a higher chance that the tumor will grow back (recur) in the same area, and it may lead the treatment team to consider further treatment.

What happens after the diagnosis?

Sinonasal angiofibroma is treated by removing the tumor with surgery, often performed endoscopically through the nose. Because the tumor bleeds easily, a procedure called embolization is often performed a day or two before surgery to block the blood vessels feeding the tumor and reduce bleeding during the operation. Because it is benign, chemotherapy is not used, but radiation therapy may be considered for large tumors that have grown into areas that are difficult to remove with surgery, such as the base of the skull.

Complete removal is important because the tumor can grow back if any part of it is left behind, and negative surgical margins reduce this risk. After surgery, follow-up usually includes imaging to check for any regrowth. In some cases, because of the link with familial adenomatous polyposis (FAP), the care team may also discuss testing for that inherited condition. The care team for sinonasal angiofibroma may include ear, nose, and throat (ENT) surgeons, interventional radiologists (who perform embolization), and, when needed, radiation oncologists.

Questions to ask your doctor

Where exactly is my tumor, and has it grown into my sinuses, eye socket, or the base of the skull?
Was the tumor completely removed?
Will I need embolization before surgery to reduce bleeding?
What is my risk of the tumor growing back after treatment?
How will I be monitored after surgery, and for how long?
Will I need imaging as part of my follow-up?
Given the link with familial adenomatous polyposis (FAP), should I be tested for that condition?
What symptoms should prompt me to contact my doctor between visits?
Is radiation therapy something I might need, and if so, why?
Which specialists will be involved in my care?