Sinonasal Inflammatory Polyp: Understanding Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
July 16, 2026

A sinonasal inflammatory polyp is a common, noncancerous (benign) growth that develops in the nasal cavity or paranasal sinuses, the air-filled spaces in the bones around the nose. It is not a cancer, and it is not a precancerous condition. A polyp is simply a piece of tissue that protrudes from a surface, and in this case, the polyp is made up of swollen, inflamed lining. These polyps are closely related to chronic rhinosinusitis, a condition caused by long-lasting inflammation of the nose and sinuses; in fact, doctors divide chronic rhinosinusitis into two forms depending on whether polyps are present. Nasal polyps affect roughly 1 to 4 percent of adults, and about 20 to 30 percent of people with chronic rhinosinusitis have them. 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 a sinonasal inflammatory polyp?

Sinonasal inflammatory polyps can be caused by chronic inflammation in the nasal cavity and paranasal sinuses, including allergies, recurrent upper respiratory tract infections, and exposure to airborne irritants. They are strongly associated with several other conditions.

Asthma — Many people with nasal polyps also have asthma, and the two conditions are often driven by the same type of underlying inflammation.
Aspirin intolerance — The combination of nasal polyps, asthma, and sensitivity to aspirin and similar anti-inflammatory drugs is a recognized condition called aspirin-exacerbated respiratory disease.
Cystic fibrosis — Nasal polyps are common in people with cystic fibrosis. Because of this, polyps found in a child usually prompt testing for cystic fibrosis, since polyps are otherwise uncommon at that age.

In many people, more than one factor is involved, and the inflammation continues even after the original trigger has resolved.

What are the symptoms?

The symptoms of a sinonasal inflammatory polyp result from blockage and ongoing inflammation in the nose. The most common symptoms are nasal congestion or a blocked nose; a reduced or absent sense of smell (often especially noticeable with polyps); nasal discharge or a sensation of mucus dripping down the back of the throat; and pressure or pain in the face. Some people also notice a change in their sense of taste, disturbed sleep, or fatigue. Small polyps may cause no symptoms at all and are sometimes found during an examination or imaging performed for another reason.

How is the diagnosis made?

Nasal polyps are usually first seen during a nasal endoscopy, an examination in which a thin scope is passed through the nose, or on imaging such as a CT scan. The diagnosis of a sinonasal inflammatory polyp is confirmed after tissue is examined under the microscope by a pathologist. This usually happens after part or all of the polyp is removed in a procedure called an excision. When only small pieces of tissue are removed, the procedure may be called a biopsy.

Under the microscope, the polyp consists of one or more rounded pieces of tissue that project from the surface. The cells covering the outside of the polyp are the same type found in the normal lining of the nose and sinuses, called the epithelium. Within the polyp, the supporting tissue (the stroma) contains numerous inflammatory cells, including neutrophils, eosinophils, plasma cells, and lymphocytes. The stroma usually looks pale because it is full of fluid, a change called edema, and this swelling is what gives the polyp its shape. The number of glands in the stroma is typically decreased. These are the same microscopic changes seen in chronic rhinosinusitis; the difference is simply that here they form a growth that projects out from the surface.

An important part of the pathologist’s job is confirming that the growth really is an inflammatory polyp and not something else. Several other growths in the nasal cavity can look like a simple polyp to the naked eye, including sinonasal papilloma, other benign growths, and, uncommonly, cancer. Examining the tissue under the microscope is what makes this distinction, which is why removed polyps are routinely sent to pathology even when the diagnosis seems obvious.

What other findings may be reported?

Along with the polyp itself, your pathology report may describe additional findings in the tissue.

Eosinophil-rich inflammation — When most of the inflammatory cells are eosinophils, the polyp may be described as eosinophilic or allergic. This pattern is part of what doctors call type 2 inflammation, and it is associated with asthma, aspirin intolerance, and an increased risk of polyps returning after surgery. It also helps identify people who may benefit from certain targeted medications.
Fungal elements — Fungus trapped within thick mucus alongside eosinophils suggests a form called allergic fungal rhinosinusitis. Special stains or fungal testing may be performed to look for this.
Reactive changes — Long-standing inflammation can make the surface lining look thickened or irritated. The pathologist confirms that these changes are reactive and not precancerous.
Findings pointing to another diagnosis — Occasionally the tissue contains features that suggest a different condition, such as an underlying autoimmune disease, in which case further testing may be recommended.

Is a one-sided polyp different?

Typical sinonasal inflammatory polyps develop on both sides of the nose. A polyp on only one side is less typical and receives closer attention, because other growths, including sinonasal papilloma and, uncommonly, cancer, tend to occur on one side. For this reason, a one-sided growth is usually removed completely and examined carefully under the microscope rather than simply watched. If your report confirms an inflammatory polyp, this reassuring result means those other possibilities were considered and excluded.

What happens after the diagnosis?

A sinonasal inflammatory polyp is noncancerous, so no cancer treatment is needed. Because polyps are usually a manifestation of ongoing inflammation rather than a one-time growth, treatment focuses on controlling that inflammation, and care is typically shared between a family doctor, an ear, nose, and throat (ENT) specialist, and sometimes an allergist.

Management usually begins with rinsing the nose with saline and using intranasal corticosteroid sprays, along with addressing contributing factors such as allergies. When polyps are large, or symptoms persist, endoscopic sinus surgery may be considered to remove them and open blocked sinuses; this is often how the tissue described in your report was obtained. Polyps commonly regrow after surgery, particularly when the inflammation is eosinophil-rich, so ongoing treatment is important. For people whose polyps remain uncontrolled despite these measures, targeted medications called biologics, which block specific parts of the type 2 inflammatory pathway, may be an option. Your care team will discuss whether this applies to you based on your symptoms, your pathology findings, and related conditions such as asthma.

Questions to ask your doctor

Were my polyps on one side or both sides?
Did my report describe mostly eosinophils, and does that mean I have type 2 inflammation?
Was the polyp completely removed?
Was there any concern that this could have been something other than an inflammatory polyp?
Were any fungal elements seen in my tissue or mucus?
Should I be tested for allergies, asthma, or aspirin intolerance?
What is the chance that my polyps will come back?
What treatment can I use to reduce the chance of them returning?
Given my pathology findings, might I be a candidate for a biologic medication?
What symptoms should prompt me to contact my doctor?