Introduction
The sinus fungal ball is defined as an agglomeration of debris and hyphae within the paranasal sinus, commonly affecting a single sinus1. It most often affects the maxillary sinus, followed by the sphenoid and ethmoid sinus, and frontal sinus affection is extremely rare implicated in only about 2% of all involved sinus2, 3, 4. There is a slight female predominance5 and, in most cases, it manifests itself during the fourth and fifth decade of life, as a result of respiratory infection by Aspergillus sp 6.
Aspergillus fumigatus and Aspergillus flavus 6 are the main species involved in fungal rhinosinusitis. Aspergillus is a genus of anamorphic fungi, which is characterized by having filamentous fungi with hyaline hyphae, septate and branched at an acute angle7. They dominate warmer areas, being more common in tropical countries. Several species of Aspergillus have importance for humans due the ability to produce toxic metabolites, mainly A. fumigatus , which has a fast-growing, bluish-green, and powdery colony. A. flavus , on the other hand, is a filamentous fungus that can produce aflatoxins and cyclopiazonic acid that results in atoxic effect on the hosts8,9.
Fungal rhinosinusitis comprises between 4% and 10% of surgical interventions in the paranasal sinuses region and can be subdivided into invasive and non-invasive10, 11. Non-invasive fungal rhinosinusitis is typical of immunocompetent patients12, classified as a fungal ball or allergic fungal rhinosinusitis13.
The slow and oligosymptomatic development of fungal ball in the frontal sinus often leads to late diagnosis, with orbital or intracranial complications as the first clinical signs14. The diagnosis of fungal ball is difficult, occasionally identified by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI)5, 15 and surgery with an endonasal endoscopic approach is the treatment of choice2, 16.