Nasal polyps are very common and are divided into three types.
Type of Polyp Characteristics Inflammatory polyps Most common
Usually multiple and bilateral
Usually >30 yrs
Association with asthma or chronic rhinitis
Translucent, moist surface
Nasal polyps in cystic fibrosis 20% of children with cystic fibrosis
Grossly resemble inflammatory polyps
Antrochoanal polyps Originates from the wall of the maxillary antrum connected with a long narrow stalk
Extends along the choana into nasopharynx
4-6% of all nasal polyps
Frequent in childhood
90% are solitary
Under the microscope, there are similar findings for all three polyp types.
Type of Polyp Histology Inflammatory polyps Localized outgrowths of the lamina propria with edema
Basement membrane thickened
Variable mixture of inflammatory cells
Nasal polyps in cystic fibrosis Lack basement membrane thickening
Few stromal eosinophils
Mucous glands and cysts contain predominately acid mcuin
Antrochoanal polyps Lack basement membrane thickening
Stroma is less edematous and more fibrotic than inflammatory polyps
Large vascular spaces may be present
The pathologist is sometimes faced with the presence of atypical cells within the stroma of these nasal polyps. These cells are most common in polyps from younger patients and also in polyps with a prominent fibrous stroma. They are most common in antrochoanal polyps and are composed of hyperchromatic nuclei with a spindled or multinucleated appearance concentrated in the submucosal region or near small vascular channels. Mitotic figures are rare and the cellularity is not increased, contrasting with a malignant sarcoma such as a rhabdomyosarcoma.
Sternberg S. Diagnostic Surgical Pathology. Third Edition. Lipincott Williams and Wilkins 1999.
Last Updated 4/1/2001
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