INTRODUCTION

Fungal rhinosinusitis encompasses a wide variety of fungal infections that range from merely irritating to rapidly fatal. Fungal colonization of the upper and lower airways is a common condition, since fungal spores are constantly inhaled into the sinuses and lungs. However, colonization is distinct from infection, and most colonized patients do not become ill with fungal infections. “Fungal rhinosinusitis” is the most appropriate term to describe fungal infection of the paranasal sinuses since concomitant involvement of the nasal cavity is seen in most cases [1].

Fungal colonization, as well as the pathophysiology, clinical manifestation, diagnosis, and treatment of invasive fungal rhinosinusitis will be discussed here. An additional disorder, which involves a hypersensitivity response to colonizing fungi, is called allergic fungal rhinosinusitis and is reviewed separately. (See "Clinical manifestations, pathophysiology, and diagnosis of chronic rhinosinusitis", section on 'Allergic fungal rhinosinusitis'.)

FUNGAL COLONIZATION

Patients with anatomic abnormalities of the paranasal sinuses that impair drainage, such as nasal polyps or chronic inflammatory states, are vulnerable to fungal colonization in these areas. Areas of mucosal injury may cause pooling of mucus and subsequent colonization by fungus. However, these abnormalities are generally of no clinical importance. Aspergillus species are the most common colonizers of the sinuses, but many other species are also reported [2].

Fungus balls — Fungal hyphae can become intertwined in dense collections and form fungus balls if there is obstruction of the paranasal sinuses [2,3]. Patients usually present with symptoms of chronic rhinosinusitis and involvement of only one sinus cavity. Computed tomography (CT) often shows a metal-dense spot within the fungus ball, and this finding was reported in 72 percent of cases in one series of 160 patients [2,4]. There may be mild sclerosis of the surrounding bone [2,3]. Surgery is required to correct the obstruction and to extract the fungus ball [2,5-7]. Recurrence after surgical removal is uncommon [2]. Glucocorticoids and antifungal agents do not offer clear benefit [2].

INVASIVE FUNGAL SINUSITIS

The marked rise in the number of immunocompromised patients has led to an increase in unusual manifestations of aggressive fungal infections. Invasive rhinosinusitis is one such form of infection that appears to be increasing in frequency. Although invasive fungal rhinosinusitis can be seen in apparently immunocompetent patients, the majority of cases involve patients with some form of immunosuppression.