oroantral fistula ( oaf ) is an abnormal communication between the oral cavity and the maxillary sinus . the chances of occurrence of oroantral communication increases , if there is an underlying peripical infection or a preexisting sinus disease . the chronic long standing nature of oaf may be due to fungal infection like mucormycosis . the sinus pathology is a predisposing factor for chronic non - healing nature of oaf . many times this aspect is overlooked and simply the diagnosis of non - specific maxillary sinusitis is given , which leads to improper treatment . the case we present here is a 34-year - old female patient [ figure 1a ] who was complaining about non - healing opening in the upper left front region and exposure of root of one tooth . the lesion started as a small swelling in the left maxillary anterior vestibular area in the region of canine eminence . after few days , patient noticed the area where the swelling ruptured was not healing and instead , it was showing small aperture . the aperture went on increasing to the present size of 0.5 cm  0.5 cm . patient revealed the history of trauma in maxillary left front teeth region during field work 2 years back . ( a ) a 34-year - old female patient presenting with mild to moderate swelling in left maxillary sinus area ( arrow ) . ( b ) intraoral examination revealed the oroantral communication ( arrow ) in maxillary left anterior labial vestibule at mucogingival junction in the area of canine . ( c ) the dorsal surface of tongue was coated with white leathery coat with central rhomboidal shaped erythematous area ( arrow ) . ( d ) the cytosmear revealed pas positive numerous long thin filaments of candidal organism ( arrow ) . budding yeast cells were seen scattered along the with pseudohyphae ( pas , 200 ) extraoral examination revealed a mild swelling in the left maxillary sinus area [ figure 1a ] . on intraoral examination [ figure 1b ] oroantral communication was noticed in maxillary left anterior labial vestibule at mucogingival junction in the area of canine . the opening was around 0.5 cm  0.5 cm in size exposing the apical third portion of root of canine . the dorsal surface of the tongue was coated with white leathery coat with central rhomboidal shape erythematous area [ figure 1c ] . no caries was detected in all maxillary left anterior teeth . on pulp vitality test maxillary left lateral incisor and canine was found to be non - vital . the clinical diagnosis of oaf secondary to chronic periapical abscess in relation to maxillary left canine was established . the conventional approach was undertaken to close the fistula and access opening was created in maxillary left canine . patient was followed up for observation of healing at closure of oaf and also to continue with root canal treatment of maxillary left canine . after 4 weeks of primary closure of oaf , still there were no signs of healing and instead the oaf was re - established as it was before commencing the treatment . patient also complained of dull gnawing pain in the maxillary sinus area and more heaviness in the same region . looking at non - healing chronic nature of oaf , the incisional biopsy from the margin of oaf was planned to seek histological changes in the region of oaf . based on histopathological diagnosis , reclosure of oaf was planned . for chronic maxillary sinusitis antibiotics and nasal wash the patient was followed - up regularly to assess for healing at oaf and check for the status of chronic maxillary sinusitis . patient reported with non - healing of oaf and even chronic maxillary sinusitis did not respond to treatment . this time to avoid surgical trauma , a cytological smear was prepared by swabbing the unhealed oaf . cytosmear stained with periodic acid schiff stain , revealed a pale homogenous stroma , with abundant acute inflammatory cells . numerous long thin filaments of candidal organism having budding yeast cells were seen scattered along with pseudohyphae [ figure 1d ] . based on the cytological features , the diagnosis of oaf with superadded candidiasis was given . after about 5 - 6 weeks patient was completely all right and clinical healing was complete . there were no sign of candida organism on repeated cytological examination at the site of closure . present case is an example for clinicians where they can learn that , sinus disease secondary to oaf is not only of bacterial origin but it could be also of fungal origin . since there is no history of extraction of tooth , oaf would have arisen due to periapical pathology secondary to trauma . the candida organisms from oral cavity might have colonized the oaf leading to sinus pathology . candida organisms can be easily detected at tissue level as candida hyphae at superficial epithelial surface , but sometime these superficial hyphae are washed away from tissue during processing in various chemicals . this might be the reason why candida organisms were not detected and diagnosed in biopsied tissue . mere presence of this fungus in oral cavity is not sufficient to produce the disease . there must be actual penetration of fungus in to the tissue , although such invasion is superficial and occurs only when there is breach in the continuity of epithelium . in present case , oaf must have become reason for the colonization of candida organisms over the maxillary sinus lining . the other predisposing factors for candidiasis can be prolonged intake of antibiotics , corticosteroids ; anemia , etc . since initially patient was diagnosed with non - specific maxillary sinusitis . so inadvertent use of antibiotics could also be responsible for occurrence of superadded infection of candidiasis with oaf . according to katzenstein , sinus mycoses can be classified as 
 non - invasive chronic mycoses ( fungus ball),allergic mycosis , chronic indolent invasive mycosis , andfulminating invasive mycoses . non - invasive chronic mycoses ( fungus ball ) , chronic indolent invasive mycosis , and fulminating invasive mycoses . types 3 and 4 are found in the immunosuppressed where as in immunocompetent , types 1 and 2 are common , with a granulomatous inflammatory response and necrosis . candida organism can grow as opportunistic pathogen especially in presence of human immunodeficiency virus ( hiv ) infection . since there was no hiv associated periodontal disease in patient , the remote possibility of hiv as cause for candida growth and occurrence of oaf could be ruled out . furthermore , the mucosa of the dorsum surface of the tongue ( filiform papillae ) may represent a site of residual colonization and reservoir of organisms . since patient 's dorsal surface of tongue was showing white coat with central erythematous area [ figure 1c ] . this would have been possible source for colonization of candida organisms in maxillary sinus through oaf . the mycetes most often involved was aspergillus fumigatus ( 76.9% ) . even after extensive literature search , no report was found for sinus formation with candida . this case is good learning lesson for clinicians and histopathologists for stepwise approach in diagnosing oaf associated with sinus disease . it is understood that sinus pathology should be primarily treated for the successful closure of oaf . for the proper treatment of sinus disease identification of causative agent ( pathogen ) therefore , sinus disease secondary to oroantral communication should be primarily screened for pathogen through simple cytological approach .
oroantral fistula ( oaf ) and oral candidiasis are common to come across as separate individual lesions . 
 however when candida organisms infect maxillary sinus through oaf then diagnosis should not be limited to clinical diagnosis only . 
 in such situation role of cytological examination can prove to be fruitful . 
 a female with chronic long standing oaf , not responding to conventional treatment approach is reported . 
 on incisional biopsy , the case was diagnosed as chronic maxillary sinusitis with oaf . 
 however patient did not respond to any treatment approach and later presented with a more progressive lesion involving maxillary sinus . 
 a cytosmear stained with periodic acid schiff stain , revealed the presence of numerous candidal hyphae . 
 finally , case was diagnosed as oaf with a superadded candidal infection . 
 patient responded well to antifungal treatment followed by reclosure of oaf . 
 we should not neglect a simple cytological examination which may prevent wrong diagnosis and wrong treatment .