Nasal Polyps Workup

Updated: Jun 16, 2016
  • Author: John E McClay, MD; Chief Editor: Ravindhra G Elluru, MD, PhD  more...
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Workup

Laboratory Studies

Direct laboratory studies at the pathologic process believed to be responsible for the nasal polyps.

Children with polyposis that is associated with allergic rhinitis should have an evaluation for their allergies; this may include a serological radioallergosorbent test (RAST) or some form of allergic skin testing. Mabry et al showed a decrease in the recurrence rate of polyps in children treated with immunotherapy directed at all antigens for which they are allergic, especially molds [8] ; therefore, allergy testing and treatment may be important in treating allergic fungal sinusitis (AFS).

Perform a sweat chloride test or genetic testing for cystic fibrosis (CF) in any child with multiple benign nasal polyps.

A nasal smear for eosinophils may differentiate allergic from nonallergic sinus diseases and indicate whether the child may be responsive to glucocorticoids. The presence of neutrophils may indicate chronic sinusitis.

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Imaging Studies

The criterion standard for evaluating nasal lesions, especially nasal polyposis or sinusitis, is a thin-cut (1-3 mm) computed tomography (CT) scan of the maxillofacial area, the sinuses axially, and the coronal plane. Perform a compatible CT scan if an intraoperative image-guided system is used. Plain film radiography has no significant value after polyps are diagnosed. Magnetic resonance imaging (MRI) is also warranted in patients with possible intracranial involvement or extension of benign nasal polyps.

CT and MRI findings can help diagnose the polyp or polyps; define the extent of the lesion in the nasal cavities, sinuses, and beyond; and narrow the differential diagnosis of an unusual polyp or clinical presentation. CF has a characteristic symmetrical bulging of the lateral nasal walls medially (see the images below).

Coronal section through the ethmoid maxillary sinu Coronal section through the ethmoid maxillary sinuses and orbits. This is a 2-year-old child with cystic fibrosis, showing complete opacification of the maxillary and ethmoid sinuses. Bulging in the medial maxillary walls is observed.
Coronal section showing soft tissue windows rather Coronal section showing soft tissue windows rather than bony windows. It indicates the infection by the thick mucus in the maxillary and ethmoid cavities by the heterogeneity of the opacification in the sinuses. Note that the nasal cavity is completely obliterated by polyp disease.
A coronal CT scan section through the orbit to max A coronal CT scan section through the orbit to maxillary sinus. The medial maxillary walls bulge medially, which is a typical CT scan view of cystic fibrosis. The ethmoid sinuses have scattered disease.

An antral-choanal polyp may show opacified maxillary sinuses with a protruding lesion heading from the maxillary antrum to the choana (see the images below).

Axial CT scan section through the maxillary sinuse Axial CT scan section through the maxillary sinuses showing opacification of the left maxillary sinus with antral-choanal polyp in the posterior nasal cavity and choana exiting from beneath the middle turbinate in the area of the ostiomeatal complex unit. Scale is in centimeters.
Coronal CT scan through the anterior sinuses showi Coronal CT scan through the anterior sinuses showing opacification of the left maxillary sinus with opacification of the inferior half of the nasal cavity on the left, filled by the antral-choanal polyp. The rest of the sinuses are clear.
Coronal CT scan section through the posterior naso Coronal CT scan section through the posterior nasopharynx showing the sphenoid sinus superiorly and the antral-choanal polyp filling the nasopharynx in the center of the scan.

A tumor, such as a rhabdomyosarcoma, may show extension of the lesion with invasion of surrounding mucosa (see the images below).

Axial MRI scan of the orbits, posterior fossa, and Axial MRI scan of the orbits, posterior fossa, and nasal cavity. The solid tumor is seen filling the posterior ethmoid complex, brain stem, cavernous sinuses, and left anterior cranial fossa.
Axial CT scan through the orbits and ethmoid sinus Axial CT scan through the orbits and ethmoid sinuses, showing the rhabdomyosarcoma in the same areas, including the posterior ethmoid complex, left middle fossa, and skull base of cavernous sinuses.

A nasolacrimal duct cyst can show dilation of the nasolacrimal duct (see the images below).

Axial CT scan section through the orbit, showing t Axial CT scan section through the orbit, showing the dilated nasal lacrimal ducts in the medial anterior area compared to the orbits. Scale on the bottom right is in centimeters.
Axial CT scan through the inferior nasal cavities, Axial CT scan through the inferior nasal cavities, showing the dilated nasal lacrimal duct cysts at the inferior location. Scale on the bottom right is in centimeters. The dilated cysts are in the center of the image.

An encephalocele can show expansion of the nasofrontal region (ie, foramen caecum) with herniation of brain or dura.

A glioma can show an isolated nasal lesion that may have a fibrous stalk to the central nervous system (CNS).

Patients with AFS exhibit heterogenous areas in the sinuses on CT and MRI; these areas consist of both the nasal polyposis and the allergic fungal mucin (see the images below). This allergic fungal mucin appears black on MRI and can be confused with the absence of disease.

Coronal CT scan showing extensive allergic fungal Coronal CT scan showing extensive allergic fungal sinusitis involving the right side with mucocele above the right orbit and expansion of the sinuses on the right.
Coronal MRI scan showing expansion of the sinuses Coronal MRI scan showing expansion of the sinuses with allergic mucin and polypoid disease; the hypointense black areas in the nasal cavities are the actual fungal elements and debris. The density above the right eye is the mucocele. The fungal elements and allergic mucin in allergic fungal sinusitis always look hypointense on MRI scanning and can be mistaken for absence of disease.
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Histologic Findings

Histologically, nasal polyps are characterized by a pseudostratified ciliated columnar epithelium, thickening of the epithelial basement membrane, and few nerve endings. The stroma of nasal polyps is edematous. Vascularization is poor and lacks innervation, except at the base of the polyp. Authors report either hyperplasia of the seromucous glands or almost absent or rare glands when comparing the polyps to the inferior or middle turbinate. Hyperplasia of the gland can cause cystically dilated and degenerated glands containing inspissated mucous.

Eosinophil cells are the most commonly identified inflammatory cell, occurring in 80-90% of polyps. Eosinophils, which are found in the polyps of patients with bronchial asthma and allergy, contain granules with toxic products (eg, leukotrienes, eosinophilic cationic protein, major basophilic protein, platelet-activating factor, eosinophilic peroxidases, other vasoactive substances and chemotactic factors). These toxic factors are responsible for epithelial lysis, nerve damage, and ciliostasis. Specific granule protein, leukotriene A4, and platelet-activating factor apparently are responsible for the mucosal swelling and hyperresponsiveness.

Eosinophils in the peripheral blood and in normal nasal mucosa usually last 3 days. In a cell culture of nasal polyps, eosinophils were present at least 12 days. This delayed apoptosis of eosinophils is mediated, in part, by blockage of the Fas receptors, typically with proteases that help begin the process of cell death. Delayed apoptosis is also mediated by an increase in interleukin 5 (IL)-5, IL-3, and granulocyte-macrophage colony-stimulating factor (GM-CSF) secreted by T cells, which help sustain the eosinophil from death. Glucocorticoids seem to help reduce polyps or polypoid reactions in patients with tissue eosinophilia, possibly, in part, by inhibiting IL-5.

Another inflammatory cell, the neutrophil, occurs in 7% of polyp cases. This type of polyp occurs in association with CF, primary ciliary dyskinesia syndrome, or Young syndrome. These polyps do not respond well to corticosteroids because they lack corticosteroid-sensitive eosinophils. Degranulated mast cells are present. Degranulation presumably occurs in a nonimmunoglobulin E–mediated fashion. Increased numbers of plasma cells, lymphocytes, and myofibroblasts also occur.

Chemical mediators

The stromata of nasal polyps have numerous mediators, including cytokines, growth factors, adhesion molecules, and immunoglobulins; polyps also contain vasoactive amines, serotonin, prostaglandins [9] , leukotrienes, norepinephrine, kinins, esterases, heparin, and histamine. The level of histamine in nasal polyps is 100-1000 times the level found in the bloodstream.

Cytokines present in polyps include the following:

  • IL-1 - Found regularly
  • IL-3 - Varies according to study, from absent to intermittent at low levels to regularly present
  • IL-4 - Inconsistently detected
  • IL-5 - Found regularly; IL-5 is essential for proliferation and differentiation of eosinophils. IL-5 is chemotactic to eosinophils, promotes the migration of eosinophils from the systemic circulation to the polyps, and inhibits eosinophil cell death.
  • IL-6 - Same as in controls (no increase)
  • IL-8 - Varies, based on study, from undetected to regularly detected; may cause sustained recruitment of leukocytes into nasal polyps and may decrease fibroblastic proliferation
  • IL-10 - Same as in controls; no increase regulated on activation, normal T cell expressed and secreted (RANTES); varies, based on study, from same as controls to regularly detected to increased levels interferon gamma; increases in eosinophils, seromucous glands, and epithelium of nasal polyps

Growth factors found in nasal polyps include the following:

  • Tumor necrosis factor alpha and beta (TNF-α, TNF-β) - Varies, depending on the study, from same as controls to regularly detected; believed to be from eosinophils
  • GM-CSF - mRNA and protein amount varies, based on study, from never to intermittent to present
  • Platelet derived growth factor - Present
  • Vascular permeable factors (VPFs) - Present
  • Vascular endothelial growth factors (VEGFs) - Present
  • Insulinlike growth factor (IGF)-1 - Present
  • Stem cell factor - Present

Adhesion molecules include the following:

  • Vascular adhesion molecule 1 (VCAM-1) - Present
  • E and P selectin - Present

Immunoglobulins (Ig) include the following:

  • IgG - No increase; same levels as in the middle and inferior turbinate mucosa
  • IgA - More in polyps than in the middle and inferior turbinate mucosa, especially IgA1 over IgA2
  • IgM - No increase, same as in the middle and inferior turbinate mucosa
  • IgD - No increase, same as in the middle and inferior turbinate mucosa
  • IgE - Increased levels compared with the middle and inferior turbinate mucosa; same level in patients without allergy as in those with allergy
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Staging

In 1993, Lund and Mackay proposed a three-point system for staging nasal polyps on the basis of endoscopic appearance, as follows [10, 11] :

  • 0 - No polyposis
  • 1 - Polyps confined to the middle meatus
  • 2 - Polyps beyond the middle meatus

Subsequently, this system was modified as follows [12, 13] :

  • 0 - No polyps
  • 1 - Polyps restricted to the middle meatus
  • 2 - Polyps extending below the middle turbinate
  • 3 - Massive polyposis, occluding the entire nasal cavity
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