- Author: John E McClay, MD; Chief Editor: Ravindhra G Elluru, MD, PhD more...
Broadly defined, nasal polyps are abnormal lesions that originate from any portion of the nasal mucosa or paranasal sinuses. Polyps are an end result of varying disease processes in the nasal cavities. The most commonly discussed polyps are benign semitransparent nasal lesions that arise from the mucosa of the nasal cavity or from one or more of the paranasal sinuses, often at the outflow tract of the sinuses.
Multiple polyps can occur in children with chronic sinusitis, allergic rhinitis, cystic fibrosis (CF), or allergic fungal sinusitis (AFS). An individual polyp could be an antral-choanal polyp, a benign massive polyp, or any benign or malignant tumor (eg, encephaloceles, gliomas, hemangiomas, papillomas, juvenile nasopharyngeal angiofibromas, rhabdomyosarcoma, lymphoma, neuroblastoma, sarcoma, chordoma, nasopharyngeal carcinoma, inverting papilloma). Evaluate all children with benign multiple nasal polyposis for CF and asthma. Educating patients about the chronicity of the disease is important to make them aware of the recurrent nature of the problem.
The pathogenesis of nasal polyposis is unknown. Polyp development has been linked to chronic inflammation, autonomic nervous system dysfunction, and genetic predisposition. Most theories consider polyps to be the ultimate manifestation of chronic inflammation; therefore, conditions leading to chronic inflammation in the nasal cavity can lead to nasal polyps.
The following conditions are associated with multiple benign polyps:
Bronchial asthma - In 20-50% of patients with polyps
CF - Polyps in 6-44% of patients with CF 
AFS - Polyps in 85% of patients with AFS
Primary ciliary dyskinesia
Aspirin intolerance - In 8-26% of patients with polyps
Alcohol intolerance - In 50% of patients with nasal polyps
Churg-Strauss syndrome - Nasal polyps in 50% of patients with Churg-Strauss syndrome
Young syndrome (ie, chronic sinusitis, nasal polyposis, azoospermia)
Nonallergic rhinitis with eosinophilia syndrome (NARES) - Nasal polyps in 20% of patients with NARES
Most studies suggest that polyps are associated more strongly with nonallergic disease than with allergic disease. Statistically, nasal polyps are more common in patients with nonallergic asthma (13%) than with allergic asthma (5%), and only 0.5% of 3000 atopic individuals have nasal polyps.
Several theories have been postulated to explain the pathogenesis of nasal polyps, although none seems to account fully for all the known facts. Some researchers believe that polyps are an exvagination of the normal nasal or sinus mucosa that fills with edematous stroma; others believe polyps are a distinct entity arising from the mucosa. Based on a review of the literature and several intricate studies of the bioelectric properties of polyps, Bernstein derived a convincing theory on the pathogenesis of nasal polyps, building on other theories and information from Tos.[2, 3]
In Bernstein's theory, inflammatory changes first occur in the lateral nasal wall or sinus mucosa as the result of viral-bacterial host interactions or secondary to turbulent airflow. In most cases, polyps originate from contact areas of the middle meatus, especially the narrow clefts in the anterior ethmoid region that create turbulent airflow, and particularly when narrowed by mucosal inflammation. Ulceration or prolapse of the submucosa can occur, with reepithelialization and new gland formation.
During this process, a polyp can form from the mucosa because the heightened inflammatory process from epithelial cells, vascular endothelial cells, and fibroblasts affects the bioelectric integrity of the sodium channels at the luminal surface of the respiratory epithelial cell in that section of the nasal mucosa. This response increases sodium absorption, leading to water retention and polyp formation.
Other theories involve vasomotor imbalance or epithelial rupture. The vasomotor imbalance theory postulates that increased vascular permeability and impaired vascular regulation cause detoxification of mast-cell products (eg, histamine). The prolonged effects of these products within the polyp stroma result in marked edema (especially in the polyp pedicle) that is worsened by venous drainage obstruction. This theory is based on the cell-poor stroma of the polyps, which is poorly vascularized and lacks vasoconstrictor innervation.
The epithelial rupture theory suggests that rupture of the epithelium of the nasal mucosa is caused by increased tissue turgor in illness (eg, allergies, infections). This rupture leads to prolapse of the lamina propria mucosa, forming polyps. The defects are possibly enlarged by gravitational effects or venous drainage obstruction, causing the polyps. This theory, although similar to Bernstein's, provides a less convincing explanation for polyp enlargement than the sodium flux theory supported by Bernstein's data. Neither theory completely defines the inflammatory trigger.
Patients with CF have a defective small chloride conductance channel, regulated by cyclic adenosine monophosphate (cAMP), which causes abnormal chloride transport across the apical cell membrane of epithelial cells. The pathogenesis of nasal polyposis in patients with CF could be associated with this defect.
As noted (see Pathophysiology), chronic inflammation (from whatever source) apparently has an initial role in the pathogenesis of nasal polyps. Multiple polyps occur in children with chronic sinusitis, allergic rhinitis, CF, and AFS. An isolated polyp could be an antral-choanal polyp, a benign massive polyp, a nasolacrimal duct cyst, or any of the following congenital lesions or benign or malignant tumors:
Nasolacrimal duct cysts
Juvenile nasopharyngeal angiofibromas
Evaluate all children with benign nasal polyposis for CF and asthma.
In the United States, the overall incidence of nasal polyps in children is 0.1%; the incidence in children with CF is 6-48%. Among adults, the incidence is 1-4% overall, with a range of 0.2-28%. Worldwide incidence is the same as the incidence in the United States.
Benign multiple nasal polyposis usually manifests in patients older than 20 years and is more common in patients older than 40 years. Nasal polyps are rare in children younger than 10 years. Although the male-to-female ratio is 2-4:1 in adults, the ratio in children is unreported. A review of articles reporting on children whose nasal polyposis required surgery showed apparently equal prevalence in boys and girls, although the data are inconclusive. The reported prevalence is equal in patients with asthma. Nasal polyps occur in all races and social classes.
No significant mortality is associated with nasal polyposis. Morbidity is usually associated with altered quality of life, nasal obstruction, anosmia, chronic sinusitis, headaches, snoring, and postnasal drainage. In certain situations, nasal polyps can alter the craniofacial skeleton because unremoved polyps can extend intracranially and into the orbital vaults.
Polyposis recurrence is common following treatment with medical or surgical therapy if multiple benign polyps are present (see Treatment, Surgical Care). Single large polyps (eg, antral-choanal polyps) are less likely to recur. The literature contains sparse data comparing treatments. Endoscopic sinus surgery appears to improve both olfaction and quality of life in chronic rhinosinusitis patients with nasal polyps.[5, 6]
Babinski D, Trawinska-Bartnicka M. Rhinosinusitis in cystic fibrosis: not a simple story. Int J Pediatr Otorhinolaryngol. 2008 May. 72(5):619-24. [Medline].
Bernstein JM, Gorfien J, Noble B. Role of allergy in nasal polyposis: a review. Otolaryngol Head Neck Surg. 1995 Dec. 113(6):724-32. [Medline].
Tos M, Sasaki Y, Ohnishi M, Larsen P, Drake-Lee AB. Fireside conference 2. Pathogenesis of nasal polyps. Rhinol Suppl. 1992. 14:181-5. [Medline].
Stammberger H. Surgical treatment of nasal polyps: past, present, and future. Allergy. 1999. 54 Suppl 53:7-11. [Medline].
Lind H, Joergensen G, Lange B, Svendstrup F, Kjeldsen AD. Efficacy of ESS in chronic rhinosinusitis with and without nasal polyposis: a Danish cohort study. Eur Arch Otorhinolaryngol. 2016 Apr. 273 (4):911-9. [Medline].
Andrews P, Poirrier AL, Lund VJ, Choi D. Outcomes in Endoscopic Sinus Surgery : Olfaction, NOSE scale and Quality of Life in a Prospective Cohort Study. Clin Otolaryngol. 2016 Apr 27. [Medline].
McClay JE, Marple B, Kapadia L, Biavati MJ, Nussenbaum B, Newcomer M, et al. Clinical presentation of allergic fungal sinusitis in children. Laryngoscope. 2002 Mar. 112 (3):565-9. [Medline].
Mabry RL, Marple BF, Folker RJ, Mabry CS. Immunotherapy for allergic fungal sinusitis: three years' experience. Otolaryngol Head Neck Surg. 1998 Dec. 119(6):648-51. [Medline].
Zhu CJ, Fruth K, Schneider A, Mann WJ, Brieger J. Impact of ozone exposure on prostaglandin release in nasal polyps. Eur Arch Otorhinolaryngol. 2011 Dec 1. [Medline].
Lund VJ, Mackay IS. Staging in rhinosinusitus. Rhinology. 1993 Dec. 31 (4):183-4. [Medline].
Lund VJ, Kennedy DW. Quantification for staging sinusitis. The Staging and Therapy Group. Ann Otol Rhinol Laryngol Suppl. 1995 Oct. 167:17-21. [Medline].
Mackay IS, Lund VJ. Imaging and staging. Mygind N, Lildholdt T, eds. Nasal Polyposis: An Inflammatory Disease and Its Treatment. Copenhagen: Munksgaard; 1997. 137-44.
Malm L. Assessment and staging of nasal polyposis. Acta Otolaryngol. 1997 Jul. 117 (4):465-7. [Medline].
Wongsritrang K, Ruttanaphol S. Clinical efficacy of a short course of systemic steroids in nasal polyposis. Rhinology. 2011 Dec. 49(5):525-32. [Medline].
Naclerio RM, Pinto J, Baroody F. Evidence-based approach to medical and surgical treatment of nasal polyposis. J Allergy Clin Immunol. 2013 Dec. 132 (6):1461-1462.e3. [Medline]. [Full Text].
Bachert C, Zhang L, Gevaert P. Current and future treatment options for adult chronic rhinosinusitis: Focus on nasal polyposis. J Allergy Clin Immunol. 2015 Dec. 136 (6):1431-40; quiz 1441. [Medline].
Holmstrom M. Clinical performance of fluticasone propionate nasal drops. Allergy. 1999. 54 Suppl 53:21-5. [Medline].
Rudmik L, Schlosser RJ, Smith TL, Soler ZM. Impact of topical nasal steroid therapy on symptoms of nasal polyposis: A Meta-Analysis. Laryngoscope. 2012 Mar 12. [Medline].
Lund VJ, Flood J, Sykes AP, Richards DH. Effect of fluticasone in severe polyposis. Arch Otolaryngol Head Neck Surg. 1998 May. 124(5):513-8. [Medline].