Rhinosinusitis

Mohamed Zaki Helal, M.D.

Professor of ORL,

Ain Shams University,

Cairo, EGYPT.

Email:                         mzhelal@mzhelal.com

Web Page:                  www.mzhelal.com

 

Fungal Rhinosinusitis

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Definition:

Fungal rhinosinusitis is an inflammatory disease of the mucosa of the nose and paranasal sinuses caused by different types of fungi.

This entity is getting more and more interest. It is estimated that 7-10% of cases of sinusitis are of fungal, not bacterial, origin.

Classification:

Many fungi are present in the nasal cavity of healthy individuals as saprophytes. Most fungi lack the ability to invade intact skin or mucous membrane as they do not produce keratolytic or proteolytic enzymes. Only a few of them can do, however, an intact immune response can abort the process from the start.

According to this fact, 2 major clinicopathological classes of fungal rhinosinusitis are recognized: Invasive and non-invasive.

Invasive fungal rhinosinusitis is further classified into acute (fulminating) type and chronic (indolent) type. Non-invasive type may be either mycetoma (fungus ball) or allergic fungal rhinosinusitis (AFRS).

Acute (or Fulminating) Fungal Sinusitis:

Pathology:

It is an aggressive inflammation of the sinonasal mucosa caused mainly by the fungus mucor; therefore, it was given the name mucormycosis. It affects only immunocompromized patients e.g. elderly diabetics, AIDS patients, those receiving immunosuppressive therapy. There is invasion beyond the mucoperiosteal lining of the PNS with intracranial extension (called rhinocerebral mucormycosis) and intraorbital extension (rhino-orbital mucormycosis). This type has high morbidity and mortality rates.

Clinical Picture:

It starts as an acute rhinosinusitis in an immunocompromized patient that progresses rapidly leading to osteitis or osteomyelitis of the sinus bony walls. Soon, manifestations of intraorbital and/or intracranial invasion follow. Swabs for fungal culture will verify the diagnosis.

Treatment:

Amphotericin-B is the drug of choice. It should be given under close monitoring because of its renal and cardiac toxicity. Surgery is limited for debridement to remove dead tissues and bone sequestra.

Chronic invasive Fungal Sinusitis:

Pathology:

It is a chronic inflammation of the sinus mucosa starting more or less similar to bacterial chronic sinusitis. It occurs in immunocompetent individuals. Infection extends beyond the mucoperiosteal lining of the affected sinus commonly to the orbit but slowly over months or years.

Clinical Picture:

In early stages it cannot be easily differentiated from bacterial chronic sinusitis. Some cases are discovered during surgical intervention for the sinus disease. Fungal sinusitis should be suspected in cases of chronic sinusitis resistant to all kinds of antibiotics used for treatment of sinusitis.

Diagnosis:

         Histopathological examination of biopsy demonstrating fungal parts in submucosa and/or intracellular in foreign body cells.

         The offending fungus can be demonstrated in smears from nasal discharge or by fungal cultures.

         CT and MRI scans: for orbital invasion, skull base erosions and intracranial invasion.

Treatment:

Mainly surgical (endoscopic surgery) under cover and followed by systemic antifungal drugs.

Mycetoma (Fungus Ball):

Pathology:

It is a mild inflammatory reaction that occurs in the sinus mucosa as a response to the accidental presence of a fungus inside the sinus cavity (usually the maxillary sinus). The fungus reproduces inside the sinus cavity and its hyphae form a ball, without any mucosal invasion. Mucosal inflammation is only due to irritation, i.e. it is infestation not infection.

Clinical Picture:

Usually there is a long history of unilateral nasal watery discharge in an immunocompetent person. There may be a history of previous penetrating injury to the affected sinus. CT scans for the PNS will show the shadow of the fungus ball inside the sinus cavity.

Treatment:

Surgical removal of the fungus ball is needed.

Allergic Fungal Rhinosinusitis (AFRS):

Pathology:

It is an allergic reaction of the sinonasal mucosa due to contact with a specific fungus or sometimes a small piece of it. When the fungus gets inside the sinus, it initiates an esinophilic reaction and possibly both type-I and type-III allergic reactions. Edema will obstruct the sinus ostium keeping the fungus inside, therefore, the allergic reaction will continue leading to the formation of polyps and the production of special type of mucin called allergic or acid mucin. Accumulation of acid mucin and polypi causes expansion and sometimes patchy erosions of the sinus walls with no invasion.

Clinical Picture:

The following criteria are diagnostic:

1.      Atopic patient.

2.      Diffuse nasal polypi (sometimes unilateral).

3.      CT scans for the PNS show an expancile lesion that has heterodensity with areas of hyperdense appearance (allergic mucin). No manifestations of bone invasion, there is only bone thinning or focal erosion due to pressure.

4.      Positive hypersensitivity skin tests for fungal extracts.

5.      The presence of characteristic acid mucin and on Histopathological examination.

There is no need to find the offending fungus as only a small fragment of the fungus can initiate the condition.

Treatment:

Endoscopic sinus surgery followed by topical steroids for a long time to avoid recurrence. It needs a very long follow up to detect early recurrences. Systemic steroids might be needed in short courses or low dose long courses.