Discussion
Globally, the prevalence of unilateral involvement of paranasal sinuses
is higher than bilaterally. However, with the present study, this index,
related to the frontal sinus fungal ball, is equivalent, corresponding
to 50% of unilateral involvement and 50% of bilateral involvement,
perhaps due to some anatomical alteration of the frontal sinus.
All reported cases of fungal ball in the frontal sinus affected male
patients, contrary to the common female prevalence in fungal ball of the
other paranasal sinuses; a possibility for this gender difference may be
hormonal. The average age of the reported cases is 65.29 years, with a
minimum age of 61.16 and a maximum age of 69 years, exceeding the age
range common to other fungal balls with paranasal sinuses; the fact that
it occurs in older patients may be related to the delay in the
proliferation of fungi, reaching more this age
group21.
The aerogenic hypothesis22 suggests that fungal spores
are deposited on the mucosa by inhalation and acquire pathogenic
capacity when in anaerobic conditions within the
sinus23. Other authors indicate osteomeatal complex
obstruction or chronic rhinosinusitis as
predisposing24. However, this theory does not explain
the cases of fungal ball that affect the sphenoid or frontal sinus. Not
all patients with occluded frontal sinuses develop a fungal ball, which
probably means that spores are not always able to reach the frontal
sinus due to the complex anatomy of the frontal recess.
Of the several anatomical sinonasal variants, the presence of bullous
shell was significantly associated with the development of fungal ball,
as well as a narrow infundibulum and anatomical variations in the region
of the ostiomeatal complex, known to cause sinus hypoventilation, may
also be related to this pathogenesis25. Concomitant to
this, our patient also had fronto-ethmoidal cells that obstructed the
frontal recess, which may explain the pathophysiological mechanism.
The therapeutic approach of choice is the endonasal endoscopy in any
paranasal sinuses, as the pharmacological treatment does not result in
improvement of the condition. The endonasal endoscopic therapeutic
approach corresponded to 80% of cases with frontal osteoplasty reserved
only for those in whom the endonasal approach is not possible.
Many important neurovascular structures are adjacent to the frontal
sinus, putting the patient at risk for orbital and intracranial
complications. Thus, the presence of a fungal ball in the frontal sinus,
although non-invasive, is potentially much more serious when compared to
the involvement of the other sinuses. Thus, early diagnosis and surgical
intervention are essential.