INTRODUCTION
Fungi are recognized as etiologic agents in a wide range of disease
states of the nose and paranasal sinuses. The International Society for
Human and Animal Mycology divides fungal rhinosinusitis (FRS) into
invasive and non-invasive types based on histopathologic evidence of
fungus penetrating host tissue.1 The sinus fungal ball
(SFB), usually found in the maxillary sinus (MSFB), is the most
frequently encountered form of non-invasive FRS in clinical
practice.1 Several studies have reported an increasing
incidence of SFB over the past few decades in Asia.2-5Yoon et al. reported annual incidence of SFB remained below 5% until
2001, but increased to over 10% since 2011 in Korea.4Liu et al. found out the incidence of SFB in the last 5 years was
significantly greater than that in the first 5 years during the 10-year
study period (2008-2017) in China.5 Studies have also
shown that SFB mostly occurs in older individuals, with a female
predominance. The average age at presentation has been reported to be 49
to 61.1 years, with women accounting for 60.1% to 76.7% of
cases.4-8
In addition, an increasing number of researchers have suggested that
adjacent odontogenic infection increases the risk of MSFB owing to the
close relationship between the antral teeth and sinus
floor.9 Furthermore, endodontic treatment on maxillary
teeth is considered to be a significant risk factor for the development
of MSFB.10 The sinus mucosa may be damaged by chemical
and physical trauma as a result of endodontic treatment, causing
inflammation. Since maxillary odontogenic pathologies and endodontic
procedures increase in frequency with aging, the role of odontogenic
etiologies in MSFB may explain the predominance of this condition in the
older population.6,11
Endoscopic sinus surgery (ESS) for eradicating SFB usually achieves good
outcomes and has been considered as the standard
treatment.7 Therefore, early diagnosis of SFB is
important to avoid unnecessary medical therapy and treatment delays.
Intralesional hyperdensity (IH), included calcifications with a nodular
or linear shape, indicate the presence of heavy metal deposition within
fungal hyphae12,13 and has been the most specific
characteristic of SFB on computed tomography (CT) scan images. In the
literature, the prevalence of IH on CT images of MSFB ranges from 66%
to 82%.5,8,14 However, for those without IH on CT
scan images, the diagnosis of MSFB continues to be a challenge. Our
previous study proposed an algorithm to improve the identification of
MSFB based on the findings of pre-operative CT
scans.15 In this study, we retrospectively
investigated patients with SFB who underwent ESS in our institute
between 2005 and 2018. The aims of this study were to elucidate the
clinical characteristics of MSFB and to increase pre-operative
identification of the presence of MSFB, especially in those without IH
on CT scan images.