Respiratory Epithelial Adenomatoid Hamartoma (REAH): Understanding Your Pathology Report

Section Editor: Jason Wasserman MD PhD FRCPC
October 26, 2026

Respiratory epithelial adenomatoid hamartoma (REAH) is a noncancerous growth that develops inside the nose. It is made up of glands lined by the same type of tissue that normally covers the inside of the nasal cavity and sinuses. REAH grows slowly and does not spread to other parts of the body.

The word hamartoma describes a disorganized overgrowth of tissue that normally belongs in that part of the body. In REAH, that tissue is respiratory epithelium, the lining of the nose whose cells are covered in tiny hair-like projections called cilia. REAH usually looks like a polyp, and it is often found in people who also have nasal polyps.

This article explains what REAH is and how a pathologist recognizes it under the microscope. It also describes the related findings that may appear in the same report, and what an REAH diagnosis means for your care.

Who gets REAH?

Respiratory epithelial adenomatoid hamartoma is most often found in adults, usually middle age or later. It is more common in men than in women and is rare in children.

REAH most often grows in the olfactory cleft. This is the narrow space at the top of the nasal cavity where the nerves for the sense of smell are located. REAH can also start on the back of the nasal septum, in the sinuses, or in the nasopharynx (the space behind the nose). In many people, REAH is present on both sides of the nose.

What causes REAH?

The cause of respiratory epithelial adenomatoid hamartoma is not known. Many people with REAH also have chronic rhinosinusitis, a long-lasting inflammation of the lining of the nose and sinuses. For this reason, ongoing inflammation is thought to contribute to the development of REAH.

REAH is also found more often in people who have already had sinus surgery for nasal polyps. In these patients, growths that return in the olfactory cleft after surgery frequently turn out to be REAH rather than ordinary polyps.

What are the symptoms of REAH?

The symptoms of respiratory epithelial adenomatoid hamartoma are similar to those of nasal polyps, because REAH blocks the nasal passage in the same way. Common symptoms include:

A blocked or stuffy nose that does not clear.
A reduced or lost sense of smell, which is especially common when REAH fills the olfactory cleft.
A runny nose, or mucus draining down the back of the throat.
Repeated sinus infections or pressure in the face.

Some people have no symptoms of REAH. In these cases, it is found only when a pathologist examines tissue removed during sinus surgery under a microscope.

How is the diagnosis of REAH made?

A pathologist diagnoses respiratory epithelial adenomatoid hamartoma after examining tissue from the nose under a microscope. Before surgery, an ear, nose, and throat surgeon may see a polyp-like growth using an endoscope, a thin camera passed into the nose. A CT scan of the sinuses often shows that the olfactory cleft is widened and filled with soft tissue, without damage to the surrounding bone. These findings can suggest REAH, but they cannot confirm it.

Surgeons usually remove the tissue during endoscopic sinus surgery, which is performed through the nostrils. Sometimes surgeons take a smaller biopsy first. In many people, surgeons do not suspect REAH before surgery and identify it only on the pathology report.

Under the microscope, REAH consists of many glands that grow down from the surface lining into the underlying tissue. The glands are lined by respiratory epithelium, the same ciliated cells and mucus-producing goblet cells found in the normal nose. Each gland is surrounded by a thick pink band called a basement membrane, one feature pathologists use to recognize REAH. The tissue between the glands, called the stroma, is often swollen with fluid, a change described as edematous.

The cells lining the glands look normal, without the abnormal features seen in cancer. The pathologist also checks for growths that can look similar to REAH. These include an ordinary inflammatory polyp, a sinonasal papilloma, and a low-grade adenocarcinoma, a type of cancer made of glands. Distinguishing them matters because each is managed differently. When routine slides do not answer the question, the pathologist may perform additional tests, as described in the next section.

Immunohistochemistry

Most cases of respiratory epithelial adenomatoid hamartoma are diagnosed without any special tests. When the diagnosis is uncertain, the pathologist may perform immunohistochemistry, a test that uses antibodies to show which proteins are present in the cells. These stains help separate REAH from glandular cancers of the nose. Results that may appear in a report include:

p63. Positive in a layer of basal cells around the outside of the glands. This outer layer is present in REAH and is usually missing in glandular cancers.
Cytokeratin 7 (CK7). Usually positive in the cells lining the glands. This is the expected result for respiratory-type glands.
CDX2. Usually negative in REAH. A positive result would raise concern for intestinal-type sinonasal adenocarcinoma, a different tumor of the nose.

Laboratories use different stains, and not every report will include these tests.

Findings reported alongside REAH.

A pathology report for respiratory epithelial adenomatoid hamartoma often describes other changes found in the same tissue. In the 2022 World Health Organization (WHO) classification of head and neck tumors (5th edition), REAH belongs to a small group of related nasal hamartomas. The findings below may appear together with REAH:

Nasal polyps. Many people with REAH also have ordinary inflammatory nasal polyps. Both may be described in the same report and, sometimes, in the same tissue sample.
Chronic rhinosinusitis. Long-lasting inflammation of the sinus lining is common in people with REAH. The report may describe inflammatory cells such as eosinophils in the tissue.
Seromucinous hamartoma. This is a closely related noncancerous growth made of smaller glands lined by a single layer of cells. REAH and seromucinous hamartoma often occur together, and some reports describe a combined or mixed lesion.
Chondro-osseous and respiratory epithelial (CORE) hamartoma. This name is used when REAH also contains small pieces of cartilage or bone. It is considered a variation of REAH and behaves similarly.

What is the prognosis for REAH?

The outlook for people with respiratory epithelial adenomatoid hamartoma is excellent. REAH is noncancerous and does not spread to other parts of the body. When it is completely removed, published case series report that it rarely grows back.

Growths can still return after surgery in people with ongoing sinus inflammation. Some of these are ordinary inflammatory polyps, and some are REAH, particularly in the olfactory cleft. For this reason, the surgeon usually examines this area during follow-up visits.

Removing REAH from the olfactory cleft often improves the sense of smell, although improvement is not guaranteed. Cancer arising in or next to REAH has been described in only a very small number of people, so the risk is considered very low.

What happens after the diagnosis of REAH?

Once a pathologist confirms respiratory epithelial adenomatoid hamartoma, the next steps depend on how the tissue was obtained. They also depend on whether you have chronic sinus inflammation or nasal polyps. Possibilities include:

REAH removed during surgery. If the surgeon removed REAH during endoscopic sinus surgery, you usually don’t need further treatment for REAH itself. Follow-up visits allow the surgeon to look inside the nose for any regrowth.
REAH found on a small biopsy. When only a sample was taken, the surgical team may consider endoscopic surgery to remove the rest of the growth. This is more likely when REAH blocks the nose or affects the sense of smell.
Ongoing sinus inflammation. Because REAH often occurs with chronic rhinosinusitis and nasal polyps, you may need to continue treating the underlying inflammation after surgery. Your care team can explain which approach fits your situation.

Surgeons usually remove REAH in several small pieces during endoscopic surgery. For this reason, pathology reports for REAH generally don’t describe margins the way cancer reports do. The surgeon determines whether the growth was completely removed at the time of surgery and during follow-up.

Questions to ask your doctor

Was the REAH completely removed, or was only a sample taken?
Where in my nose did the surgeon find the REAH, and was it on one side or both?
Does my report also describe nasal polyps or chronic rhinosinusitis?
Did my report mention seromucinous hamartoma, or cartilage and bone in the growth?
Were any special stains needed to confirm the diagnosis?
Could the REAH explain my loss of smell, and is my sense of smell likely to improve?
Do I need more surgery, or is follow-up enough?
How will you check whether the REAH or polyps come back?
What treatment do I need for the inflammation in my sinuses?
How often should I see an ear, nose, and throat specialist for follow-up?