Not all cases of sinusitis are due to bacterial or viral infections. Some cases of sinusitis may result from fungus growth within the sinuses. Fungus is neither bacteria nor virus, but is the general term encompassing molds and yeasts. You are exposed to a variety of fungi each day. You contact fungus by inhalation of mold spores and ingestion of foods contaminated by molds. Fungi commonly colonize the skin, the upper and lower gastrointestinal tract, the respiratory tract (nose, sinuses and lungs) and the vagina. These colonies rarely cause symptoms of disease. They are just present in minute amounts and are suppressed by your immune system and competing bacteria.
Given the great amount of fungi exposures you have, remarkably few fungal infections require medical treatment. However fungal sinus disease does require medications and treatment and increasingly is recognized as a source of chronic sinusitis. In part fungal sinusitis may result from damage to the sinus membranes by prior bacterial infections, surgery and frequent use of antibiotics.
In 1985, physicians from The Asthma Center were the first to describe a now widely used classification system for fungal sinus disease. There are currently 5 recognized kinds of fungal sinusitis. Fungal sinusitis is often diagnosed following sinus surgery when a sample of infected sinus mucosa is removed. The presence and type of fungus is then identified by special fungal stains and/or cultures.
The 5 types of fungal sinus disease are:
Allergic Fungal Sinusitis
Allergic fungal sinusitis is the most common fungal infection associated with chronic sinusitis. This condition often occurs if you have nasal polyps and sinus disease. It is usually resistant to conventional medical and surgical treatments. Tissue within the sinuses is often covered with a characteristic thick gel-like discolored mucus filled with allergy cells (eosinophils). This gel is often described as “allergic mucin” and often contains fungal elements when properly stained and examined microscopically. Treatment of allergic fungal sinusitis includes surgery, oral and nasal corticosteroids, allergy injection therapy, leukotriene modifiers, antihistamines and oral decongestants. Unfortunately oral antifungal treatment is usually not effective.
Chronic Sinusitis Fungal Granulomatous
Chronic granulomatous fungal sinusitis is a persistent form of sinusitis seen in otherwise healthy individuals with no complications involving the lung. This fungal disorder responds well to surgery without use of antifungal therapy.
Invasive Fungal Sinusitis
Invasive fungal sinusitis occurs in individuals with weakened immune systems. It is caused by invasion of fungus directly into the mucous membrane tissues, the walls of blood vessels and bony structures of the sinuses. You are susceptible to this illness if you have been treated with high doses of corticosteroids or immunosuppressant medications, suffer from immunodeficiency, or have advanced cancer. This is a serious infection associated with high mortality.
Mycetoma or Fungal Balls
Mycetoma or fungal balls (tangled masses of fungal elements) are seen in those who have had previous sinus disease, trauma, surgery, or foreign bodies in the sinus cavity. With this condition there is no tissue invasion. The fungus slowly grows within the sinuses without penetration into the mucosal lining. Surgical removal of the fungus ball usually cures the problem.
Eosinophilic Fungal Sinusitis
Recent research from the Mayo Clinic has described a fifth form of fungal sinusitis called eosinophilic fungal sinusitis. In fact, these researchers claim that most cases of chronic sinusitis are related to the presence of fungus in the sinuses. Mayo Clinic researchers have shown that fungal cultures may be positive in 96% of those with chronic sinusitis. These procedures also showed the presence of allergic mucin. More recent studies from the Mayo Clinic have suggested that nasal antifungal drugs (amphotericin for 3 - 6 months) improved symptoms in individuals with this disorder. The data submitted by the Mayo Clinic has not yet been confirmed by other investigators.