Differentials
Acute rhinosinusitis
SIGNS / SYMPTOMS
No symptoms or signs reliably differentiate acute from chronic rhinosinusitis. Both present in a similar fashion, although symptoms are generally less pronounced in chronic sinusitis. The distinction between the two is based upon the duration of symptoms (≤4 weeks for acute rhinosinusitis vs. ≥12 weeks for chronic rhinosinusitis). Fatigue may be more common in chronic rhinosinusitis, whereas fever and acute toxicity are associated with acute (bacterial) rhinosinusitis.
INVESTIGATIONS
No differentiating tests.
Allergic rhinitis
SIGNS / SYMPTOMS
Clear rhinorrhoea, itching, sneezing, ocular irritation, and seasonality of symptoms suggest a predominant allergic component.
INVESTIGATIONS
Scratch and intra-dermal tests will show oedema (wheal) and erythema (flare) if positive for specific allergens. In vitro-specific IgE determination may detect allergic response to a specific allergen.
Allergic fungal rhinosinusitis
SIGNS / SYMPTOMS
Similar symptoms; often unilateral.
INVESTIGATIONS
CT scan shows hyperdensities within opacified sinuses. MRI has classic appearance of dropped signal on T2-weighted images. Operative findings include thick 'peanut butter'-consistency mucus, while histology demonstrates non-invasive fungal elements and Charcot-Leyden crystals.
Sinonasal tumours (benign and malignant)
SIGNS / SYMPTOMS
Can occur in the sinuses, nasal cavity, or nasopharynx. Treatment for chronic rhinosinusitis usually fails; symptoms are often unilateral and refractory. Constitutional symptoms may be present.
INVESTIGATIONS
CT/MRI may show invasion or destruction of nearby structures that is suspicious for malignancy. Biopsy/tissue histology may reveal malignant cells. Histology differs widely according to multitude of benign and malignant neoplasms.
Turbinate hypertrophy
SIGNS / SYMPTOMS
Predominant complaint is nasal obstruction, which often improves with topical nasal decongestion. Associated with allergy or nasal irritation.
INVESTIGATIONS
Anterior rhinoscopy may show inflamed, swollen (hypertrophic) turbinates that respond to topical decongestion.
Foreign bodies
SIGNS / SYMPTOMS
Common in children. Symptoms may be unilateral with specific onset.
INVESTIGATIONS
Foreign bodies can be seen on anterior rhinoscopy, endoscopy, and imaging studies (e.g., CT). Associated mucosal inflammation and purulence may be seen.
Juvenile nasopharyngeal angiofibroma
SIGNS / SYMPTOMS
Invariably occurs in adolescent boys, who present with nasal obstruction (often unilateral) with frequent nosebleeds.
INVESTIGATIONS
Nasal endoscopy shows vascular-appearing nasopharyngeal mass. CT and MRI will show mass centred in area of sphenopalatine foramen; often extending medially into nasal cavity/nasopharynx and laterally to involve pterygopalatine fossa and possibly infratemporal fossa.
Migraine
SIGNS / SYMPTOMS
Symptoms unique to migraine include photophobia, aura, unilateral pain (often throbbing), and visual disturbances. Some patients will not have the classic migraine symptoms but instead a mid-facial pain variant. Most patients presenting with primary complaint of headache or facial pain will fall into this category.
INVESTIGATIONS
A normal sinus CT scan and unremarkable endoscopy serve as objective evidence against a sinonasal cause for headache. A trial of a triptan can be diagnostic for migraine as a cause for headache or facial pain.
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