Molds, yeasts and other fungi are present in our surroundings, the air we breathe and even in our nose and sinuses. Studies have shown that almost all sinuses – healthy or not – have traces of fungi. When a person has a healthy immune system they do not react to normal levels of fungus in their environment. However, when the body's immune system isn't working properly, fungi may find an opportunity to invade the body. The moist, dark cavities of the sinuses can be a natural home to the invading fungi resulting in fungal sinusitis. There are several types of fungal sinusitis with different symptoms, severity and treatments. Fungal sinusitis is broadly classified into invasive and non-invasive types.
A patient's medical history and a careful clinical examination will indicate the presence of a fungal sinusitis but examination of tissue samples under a microscope will confirm the diagnosis. In addition, medical imaging including CT and MRI scans are often ordered.
Mycetoma Fungal Sinusitis or Fungus Ball
Patients with chronic sinusitis and nasal polyps often accumulate years of stale mucus in the larger sinus cavities. Saprophytic fungi (those that live on dead or decaying matter) will grow in the sinus and live on the mucous and dead cells that become trapped in the cavity. This type of fungal sinusitis produces clumps of spores, a "fungal ball". Typically, only a single sinus is involved. Generally, the fungus does not cause a significant inflammatory response, but sinus discomfort occurs and sometimes, bacteria can cause super-added infection in the sinus affected by the fungus ball. They do not attack the living tissue, but may create inflammation that allows the swelling and the growth of nasal polyps. Antibiotics and medications for ordinary yeast infections have no effect on fungus balls, which cause chronic nasal congestion and postnasal drainage. The fungus balls can often be seen on CT scans, and confirmed with magnetic resonance imaging (MRI).
Allergic Fungal Sinusitis
Patients with distinct allergies to fungus may accumulate mold in the sinuses that perpetuates the allergy. The chronic exposure creates nasal polyps, asthma, and a very thick mucus. Usually, allergic fungal sinusitis (AFS) affects more than one sinus on one side. However, all sinuses on both sides may be involved in severe cases. Allergy testing to fungi is positive. Sinus CT scans also have a typical appearance. Patients diagnosed with AFS usually have a history of allergic rhinitis, and the onset of AFS development is difficult to determine.
Invasive Fungal Sinusitis
It is rare for fungi to attack living tissue, but this can occur in patients who are debilitated or immune compromised, such as those with advanced AIDS, poorly controlled diabetes, or advanced cancer requiring chemotherapy. The fungi cause thrombosis (blood clots) that lead to tissue death, and then they live on the dead tissue. Invasive fungal sinusitis is a rare, but serious condition that can be fatal. The disease leads to progressive destruction of the sinuses and can invade the bony cavities containing the eyeball and brain. Acute invasive fungal sinusitis is the most serious form of fungal sinusitis and can develop in less than four weeks and can actually progress over hours and days. Chronic invasive fungal sinusitis is a slower destructive process that develops over a few months.
Mycetoma Fungal Sinusitis or fungus ball. The noninvasive nature of this disorder requires removal of the fungus ball through endoscopic sinus surgery (minimally invasive surgery). An anti-fungal therapy is generally not prescribed. Most patients have excellent results from surgery, and may not require any further treatment.
Allergic Fungal Sinusitis. Thick fungal debris and mucin (a type of mucus) are developed in the sinus cavities and must be surgically removed to clear polyps and allergic mucin, and to restore the ventilation and drainage of sinuses.. Recurrence of AFS is not uncommon once the disease is removed. Antiinflammatory medical therapy and immunotherapy are typically prescribed to prevent AFS recurrence. Patients may also benefit from treatment of allergy with immunotherapy (allergy shots or drops) and antihistamines. Anti-fungal treatment is usually not required, but in severe recurrent disease, anti-fungal therapy may be needed.
Invasive Fungal Sinusitis. Treatment of invasive fungal sinusitis involves a combination of aggressive surgical and medical therapy. Repeated surgery may be necessary to remove all dead tissue. Medications such as anti-fungal drugs and those that help restore the immune status of the patient are key to improving survival.