Fungal Sinusitis
Fungi can affect your sinuses in many ways, and it can confusing even for those training to become ears, nose, and throat physicians (otolaryngologists). This post is meant to provide a basic understanding of the most common types of fungal sinusitis. This is not meant to be a comprehensive overview of the topic as that is well beyond the scope of this blog. That level of material would be more suitable for a book chapter or review article. The main types of fungal sinusitis are fungal balls, allergic fungal sinusitis, acute invasive fungal sinusitis. Other conditions include chronic invasive fungal sinusitis, but this is quite rare so I won’t discuss it here.
Fungal Ball
First, let’s talk about fungal balls. The inside of your sinuses tend to be warm and humid. You know what likes to grow in warm and humid environments? That’s right, fungus. Under normal circumstances, certain fungal elements might find their way into one of your sinuses. Because the environment in the sinuses is conducive to fungal growth, the fungus begins to grow. This leads to a collection of fungal elements that forms what we call a fungal ball. This occurs most commonly in the maxillary sinus (the cheek sinus). In some cases, fungal balls cause no symptoms; however, they can cause the typical symptoms of sinusitis with nasal congestion or obstruction, nasal drainage, facial pressure, or trouble with your sense of smell. Fungal balls are typically diagnosed on imaging scans such as CT scans. Surgical drainage of the fungal ball with endoscopic sinus surgery is often recommended, and you can see my video here. Most commonly, no further treatment after surgery is required. In the case of a fungal ball, your sinuses are simply serving as home to a collection of fungus or fungal elements. Your sinuses and immune system are not overreacting to the fungus, which is why no medical treatment is typically necessary after the fungal ball has been removed.
Allergic Fungal Sinusitis
Allergic fungal sinusitis, on the other hand, occurs when your sinuses and immune system are overreacting to normal fungal elements in the environment, therefore, in your sinuses. In this scenario, your immune system provides a robust allergic response to otherwise normal fungal elements resulting in an intense inflammatory cascade. This ongoing inflammation causes you to develop allergic fungal sinusitis, a certain type of chronic sinusitis with nasal polyps. In this type of chronic sinusitis, your affected sinuses often fill with something called eosinophilic mucin which is thick mucus of peanut butter consistency that can be difficult to expel. Certain criteria such as allergy to fungus and characteristic CT scan findings such as double density or characteristic expansile changes are used to diagnose this condition. Treatment typically consists of a course of medical management followed by endoscopic sinus surgery if the condition doesn’t resolve. Ongoing treatment with topical steroids after surgery is typically recommended to help minimize the ongoing allergic reaction and inflammatory cascade.
Acute Invasive Fungal Sinusitis
Invasive forms of fungal sinusitis are much more serious and often are life threatening. Acute invasive fungal sinusitis affects patients who are immunocompromised and typically occurs in patients who are hospitalized and are quite ill. In these cases, otherwise normal fungi in the nose and sinuses begin to destroy the blood vessels in the sinonasal lining. This occurs because the immune system is not functioning properly and cannot keep these fungi from invading the sinonasal tissues. The condition is diagnosed with a high degree of suspicion, nasal endoscopy, and imaging studies such as a CT and/or MRI scan. This is usually a life threatening emergency and treatment of this condition is complicated and requires reversing the immune compromising condition (when possible), surgical treatment, and antifungal medication.
