A hospital-based observational study on clinical and radiographic findings in COVID-19 associated rhinomaxillary mucormycosis: revealing the pandora box

Mucormycosis is a rare, rapidly spreading, fulminant, opportunistic infection that is caused by a group of filamentous molds. During the second wave of COVID-19 India reported most of the cases of mucormycosis which is termed as COVID-19-associated mucormycosis (CAM). Aim The purpose of this study is to describe and understand the clinical and radiographic findings related to COVID-19 associated rhinomaxillary mucormycosis. Methods In this observational study 76 individuals with proven rhinomaxillary mucormycosis were included. The demographic profile, predisposing factors, anatomic structures involved, oral manifestations, radiographic findings management, and 90-day mortality were recorded and analyzed. Results Among 76 individuals with COVID-19-associated rhinomaxillary mucormycosis diabetes mellitus was present in 93.42% of cases. Almost all patients received corticosteroids during COVID-19 treatment. The maxilla was most commonly involved in around 98.6% of cases. Interestingly 1 case involving the mandible was noted and the maxillary sinus was the most commonly involved. Mortality occurred in 1.31% (n=1) of cases. Conclusion Diabetes was the most common predisposing factor. Administration of corticosteroids was evident. A considerable number of patients developed diabetes during the treatment of COVID-19. Early signs and oral manifestations of rhinomaxillary mucormycosis play a pivotal role in the early diagnosis and prompt treatment to reduce mortality and morbidity in COVID-19 associated-rhinomaxillary mucormycosis patients.


Introduction
Although the primary pathology of COVID-19 is pneumonia and respiratory failure, secondary infections are common and attribute significantly to morbidity and mortality 1 . Fungal infections are least common than bacterial infections, nevertheless are usually more invasive and fatal 2 . Mucormycosis is a fungal infection caused by fungi known as Mucorales. It is highly aggressive with a tendency for widespread infection. This infection occurs by inhalation of spores. The fungal spores adhere to the respiratory epithelium and transform into hyphae causing angioinvasion, leading to endothelial injury, thrombosis, and necrosis. The fungus can then spread to various organs rapidly to cause disseminated mucormycosis. If the diagnosis and management are delayed, the prognosis is poor 1 .
Several factors increase the risk of invasive fungal infections and mucormycosis in patients with COVID-19. The most important predisposing factor is hyperglycemia which may decrease the ability of the body to fight infections 3 . Prolonged use of a high dose of corticosteroids and drugs like tocilizumab used in moderate and severe disease may also increase predisposition for fungal infections 4 . Severe COVID-19 disease is associated with the cytokine storm, and it is associated with producing insulin resistance and hyperglycemia and the use of steroids aggravates it, as corticosteroids have hyperglycemic action thus providing the milieu for seeding by mucor. This cytokine storm triggers a hyperinflammatory and hypercoagulatory response, which disrupts endothelial cell integrity thus causing organ damage such as lung injury and pancreatic injury 5 . The SARS-CoV-2 confers pancreatic islet injury and acute diabetes onset by binding to the ACE2 receptor, one more assumed factor for increased risk of mucormycosis in COVID-19 is intracellular iron overload signified by increased ferritin levels, which leads to the formation of reactive oxygen species 6 . Widespread endothelial injury in patients with severe disease can upregulate endothelial receptor glucose-regulated protein (GRP 78), which is responsible for increased adhesion and penetration of Mucorales to the endothelium 7 . The treatment modalities available for the treatment of mucormycosis are aggressive debridement of infected hard and soft tissue and parenteral antifungal therapy such as Liposomal Amphotericin B, lipid Amphotericin B, Posaconazole, and itraconazole. Functional endoscopic sinus surgery (FESS) is an endoscopic surgical debridement of the paranasal sinuses used in the cases of rhinomaxillary mucormycosis 8 .
The commonest reported form of mucormycosis in literature is rhinomaxillary mucormycosis 9 . There are other recently published reports as well as case series that reported similar findings 10,11 . This study aims to describe and understand the clinical and radiographic findings related to COVID-19-associated rhinomaxillary mucormycosis.
This study aimed to describe the predisposing factors, gender predilection, age, clinical signs and symptoms, oral manifestations, anatomical structures involved, treatment received and mortality related to COVID-19-associated rhinomaxillary mucormycosis in patients who reported to the Dept of Oral Medicine and Radiology with dental complaints.

Materials and methods
This observational hospital-based study was conducted in a dental hospital-based setting. The study sample consisted of confirmed cases of rhinomaxillary mucormycosis with a previous history of COVID-19 who reported during the 2 nd wave of COVID-19 from March 2021 to December 2021 in India. Confirmation of diagnosis was based on clinical and radiological features in the paranasal sinus view, computed tomography (PNS CT), and demonstration of Mucor on potassium hydroxide (KOH) staining or histopathological examination using periodic acid-Schiff stain (PAS) ( Figure 1) and Grocott's Methenamine Silver Stain (GMS) (Figure 2). Patients with fungal culture positive for Mucorales were included in the study.  A total of 76 patients were included in the study. Patients who had rhinomaxillary mucormycosis with negative history of COVID-19 were excluded from this study. Clinical data was retrieved from the clinical records. These included demographic data like age and gender. Details of COVID-19 infection were noted which included duration of hospitalization and intensive care unit (ICU) stay, the need of a ventilator, and use of corticosteroids and other medicines. History of co-morbidities like diabetes, coronary heart disease, kidney disease, cancer, organ transplant, chronic lung diseases, etc. was recorded. Finally, the clinical details of mucormycosis were extracted including the oral manifestations, anatomical structure involved, sinus involvement, treatment provided, and outcome. All data were entered in a central Google spreadsheet and the patient information was de-identified. The data was checked by two investigators.

Results
A total of 76 patients with COVID-19-associated "rhinomaxillary mucormycosis" were included in this study. The mean age of occurrence was 52 years with 72 males (94.73%) and 4 females (5.26 %) given in The maxilla was the most commonly involved anatomic structure in 98.6% (n=75) of the cases, although 1 case of mucormycosis involving the mandible was noted. The right maxilla 64% (n=48) was more commonly involved than the left maxilla 36% (n=27). The most common oral manifestation was a periodontal abscess ( Figure 3) with mobility seen in 50% (n=38) of patients, followed by necrotic bone (Figure 4) with pus discharge in 42.1% (n=32) of patients [ Table 2]. In radiographic findings, right maxillary sinus 36% (n=27) was more commonly involved than the left side 26.6% (n=20), although in advanced cases a bilateral sinus involvement was observed in 37.3% (n=28). Other paranasal sinuses were involved in clinically advanced disease. Orbit involvement and other structures of the skull were involved in severe cases. None of the patients showed evidence of brain involvement. [ Table 3].      13 . A retrospective countrywide study revealed that diabetes mellitus is predominant in 79% and steroid use in 87% of patients with rhino-orbito-cerebral mucormycosis associated with COVID-19 11 . In an updated systematic review comprised of 233 patients from India and 42 from the rest of the world, diabetes was identified as the most common primary risk factor for CAM in India than in other countries. A study from Egypt in 21 patients with CAM also found a high prevalence of diabetes (90%) 14 .
In our study, all patients received systemic corticosteroids during the treatment of COVID-19. The interesting fact here is although the prevalence of diabetes was similar in most studies, the use of corticosteroids is less in some studies (85% in a recent systemic review) 15 . Another notable finding was that, 53.52% developed diabetes mellitus during the COVID-19 treatment, new onset of diabetes was reported in association with COVID-19 16 . The nasal mucociliary clearance is the primary distinctive defense mechanism of the paranasal sinus against various antigens. This mechanism guards the upper respiratory system against numerous inhaled particles and microorganisms. However, it becomes one of the critical factors for the growth of fungus together with the inflammation of the upper airway, in patients requiring prolonged hospital stay with supplemental oxygen therapy 17 , Mild thrombocytopenia has been detected in 58-95% of patients with SARS-CoV-2 infection. Platelets possibly hamper the growth of fungi are (i) directly by adhering to Mucorales hyphae to form a thrombus. (ii) Indirectly, platelets secrete pro-inflammatory and anti-inflammatory cytokines such as TGF-β and Thrombocidins which may act against Mucorales 18 . Corticosteroids used for suppression of inflammatory mediators and cytokines in severe COVID-19 cause suppression of lymphocytes and also cause hyperglycemia by promoting gluconeogenesis and inhibiting glycolysis thus there is an increased incidence of mucormycosis in patients with a history of corticosteroid use 19 .
The maxilla (98.6%) was the most commonly involved jaw bone in our study. Interestingly 1 case involving the mandible was seen, although in bacterial osteomyelitis, the mandible is most common than the maxilla 20 . The most common oral manifestations were multiple periodontal abscesses with mobility (50%) and necrotic bone with pus discharge (42.1%) followed by extra-oral swelling with necrotic bone (7.89 %). Bacterial osteomyelitis is associated with the symptoms of localized intense pain, fever, tenderness, etc. 21 although in the cases of COVID-19-associated rhinomaxillary mucormycosis no such symptoms were reported by the patients.
On radiographic examination, the maxillary sinus was the most commonly involved. Bilateral maxillary sinus involvement (37.3%) was most commonly seen followed by right maxillary sinus involvement (36%). Ethmoidal sinus was the second most involved paranasal sinus. Orbital involvement was found in advanced cases of rhinomaxillary mucormycosis. Other vital structures such as infratemporal fossa, pterygopalatine fossa, sphenopalatine foramen, ethmoid air cells, sphenoid bone, and zygoma were seen in clinically advanced cases. This is the first study reporting oral manifestations and radiographic findings of COVID-19-associated rhinomaxillary mucormycosis. Functional endoscopic sinus surgery under general anesthesia (FESS) was employed in the majority of patients reported with sinus involvement. Depending upon the area of bone involvement resection of jaw bone was done. Due to resection of the bone, there was loss of a masticatory function. The mortality rate observed was 1.31 %, possibly due to early diagnosis and aggressive treatment. Another interesting fact is that the fatality rate of cases reported from India (36.5%) is less than the globally reported cases (61.9%) this might be due to the predominance of rhinomaxillary mucormycosis type of mucormycosis 18 . The aggressive nature of Mucor species and mucormycosis warrants attention. Dentists should be able to identify the early signs of mucormycosis so that early treatment is instituted thereby reducing morbidity and mortality. Delay in the diagnosis of rhinomaxillary mucormycosis has led to many patients becoming severely disfigured 19,22 . The increase in mucormycosis cases in the Indian context appears to be due to diabetes (high prevalence genetically). Rampant use of corticosteroids in COVID-19 was reported in many studies. Corticosteorids lead to an increase in blood glucose and consequently increase the chances of developing opportunistic fungal infection. COVID-19 leads to reduced immune functions due to cytokine storm, lymphopenia, and endothelial damage. The combined damaging effects of corticosteroid therapy and SARS-COV 2 virus seem to have led to a high prevalence of rhinomaxillary mucormycosis 23 . All efforts should be made to maintain optimal hyperglycaemia and only judicious evidence-based use of corticosteroids in patients with COVID-19 is recommended to reduce the burden of fatal mucormycosis 23 .
Oral manifestations of mucormycosis in COVID-19 patients are frequently seen in the palate and may include varying degrees of mucosal discoloration, swelling, ulcerations, and superficial necrotic areas involving the palate (Figure 1), tooth mobility, multiple periodontal abscess, bone necrosis and exposure with dark eschar formation 24 . Hence, palatal ulcerations could be the primary presenting symptom, leading the patient to the dentist, who can be the first clinician to recognize an infection leading to the diagnosis of rhinomaxillary mucormycosis 25 . Therefore, a non-specific palatal ulcer can be considered as the presenting sign of mucormycosis, and a dental practitioner must be alert to initial signs and symptoms of this disease, specifically when evaluating the high-risk patients. Early diagnosis of mucormycosis is critical, as treatment should start as soon as possible in an attempt to decrease mortality 26 .
The role of dentists is critical because mucormycosis primarily occurs around rhinomaxillary or rhinocerebral areas involving facial tissues, palate, alveolar bone, and mandibular bone. Therefore, dental professionals should be alert of symptoms of mucormycosis. In addition to palatal lesions, atypical symptoms such as sinus pain, facial pain, unanticipated odontalgia of otherwise sound teeth, or patient deterioration after dental therapeutic interventions should alert clinicians to seek confirmation of the diagnosis and promptly start optimal treatment 27 .

Limitations
We could not assess the prevalence of COVID-19 associated rhinomaxillary mucormycosis as this is a single-center study conducted in a dental OPD in India.
In conclusion, this single-center observational study from India found a higher prevalence of diabetes mellitus and steroid administration in COVID-19-associated rhinomaxillary mucormycosis. Maxillary sinus was most commonly involved in the paranasal sinus. Many patients presented with aggressive periodontal disease. In the era of the COVID -19 pandemic, any patient who presents with aggressive periodontal disease and palatal ulcerations should be investigated for Mucormycosis.

Conflict of interest
Authors declare no conflict of interest. This study is self-funded.

Ethics
Obtained Ethical clearance from the institutional ethical committee.

Ethical clearance no: 1382
Source of funding