Pathology Spotlight: The Pathology of Allergy – Nasal Polyps

As it is Allergy Awareness Week, this month’s Pathology Spotlight blog is about Nasal Polyps. 

polypi
Nasal polyps illustrated in a specimen from the Museum’s Collection

This specimen shows a section through the head in which nasal polyps can be seen in the nasal cavity. Nasal polyps often show the stalked appearance seen here, growing out from the nasal or sinus lining where they can become quite large as in this case. However they are symptomless and harmless if they do not become large enough to cause a blockage or a runny, irritated nose.  Nasal polyps generally arise as a result of chronic allergic inflammation in the lining of the nasal cavities and sinuses.

Chronic inflammation in these regions is very common, afflicting about 10% of European adults and about 3% of people develop nasal polyps to some extent.  The exact events that lead to the inflammation that causes polyps is still unknown, but certain associations have been shown; for instance nasal polyps arise especially in chronic sinusitis due to fungal infection, in people with aspirin allergy, in hay fever-sufferers and in individuals who have the chronic infective lung condition cystic fibrosis.

An eosinophil (the cell typically found in allergic tissue) surrounded by red blood cells
An eosinophil, the cell typically found in allergic tissue, surrounded by red blood cells

The eosinophil is the inflammatory cell that is associated with allergic inflammation and accumulation of eosinophils in the nasal lining is characteristic of polyp development. Eosinophils are often found in a large numbers in polyps themselves confirming their allergic origins. Nasal polyps can be difficult to treat as they tend to return. However the polyps may shrink if anti-inflammatory steroid medication is used. Failing that surgery can be carried out whereby a tube with a video camera at one end is inserted into a nostril so the surgeon can see inside the nose and sinuses. Surgical instruments, such as a tiny motorised revolving shaver is then guided up the nostril and used to remove the polyps.

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