Monday, November 26, 2012

Allergic fungal sinusitis

Allergic fungal sinusitis


Definition
Allergic fungal sinusitis (AFS), a type of noninvasive fungal sinusitis, is an inflammation of the paranasal sinus mucosa due to allergy to fungi. The inflammation may remodel and erode bone although it is indolent. AFS generally occurs in more than one sinus simultaneously.

In AFS, fungi occupying the atopic immunocompetent patient’s sinuses work like an allergen and trigger cellular immune and humoral responses. As a result, inflammation occurs and blocks the sinuses, and disturbs the secretion balance, encouraging proliferation of the fungi.
AFS is often confused with allergic rhinitis. A carefully examination is therefore required to avoid complications and consequent increase in discomfort and treatment cost.
Main fungal causes of sinusitis
Earlier Aspergillus species of the fungus was considered as the main cause of the sinusitis. However, now-a-days the medical community believes that dematiaceous fungi, aerosolized environmental fungi, are the principal agents that trigger AFS. Dematiaceous is a group of Alternaria, Biploaris and Curvularia fungi species, which are referred to as ABC-D. Other dematiaceous fungi include Exserohilum and Caldosporium species. In some patients, aspergillus is still one of the causes of sinusitis.



AFS Diagnosis
There is no standard diagnostic criterion to detect AFS. However, some of the diagnostic features follow:
  • Immunocompetency
  • Degeneration of the epithelial cells
  • Viscous brown nasal discharge
  • Fungal elements found in culture or stains
  • The patient is hypersensitive to fungal antigens.
  • Fungi have not invaded the bone, blood vessels and submucosa.
  • Mucosal invasion absent in the tissues collected from the mucosa
  • Proven presence of fungal specific immunoglobulin E (IgE)
  • A histological examination reveals that mucin featuring eosinophils is attached to the inflamed mucosal tissue. The mucin featuring eosinophils is known as allergic mucin.
  • Allergic mucin is tenuous and thick.
  • Sinus secretions feature fungal hyphae, Charcot Leyden crystals and eosinophils. The number of eosinophils is extremely large.
  • No air-fluid levels in the computed tomography (CT) findings
  • Affected sinus is completely opacified in CT.

Signs and symptoms of AFS
  • Rhinorrhea
  • Sinus pressure
  • Headache
  • Symptoms of chronic sinusitis, allergic rhinitis and nasal airway obstruction, such as postnasal drainage, purulent nasal discharge and nasal congestion
  • Chronic sinusitis patient might have undergone a surgery(s).
  • Extreme symptoms include nasal obstruction and nosebleed.
  • The patients may already suffer from allergic disorders or asthma.
  • Other symptoms include visual disturbances, proptosis and periorbital swelling.

Do not ignore any of the causes of sinusitis to avoid complications.

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