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