Introduction

While the world is trying to recover from the clutches of the deadly virus causing COVID -19, India is hit with a severe and potentially fatal fungal epidemic of mucormycosis. In past this angioinvasive disease was caused by fungi Mucoralaean in individuals with various conditions of immune suppression like uncontrolled diabetes, corticosteroid therapy etc. [1, 2]. In a COVID—19 patient interaction of several factors like immune dysregulation, steroid therapy, exacerbation of preexisting diabetes may allow the mucoralean fungi to cause this disease [3]. The opportunistic infection of mucormycosis has been reported globally; however, it has reached alarming proportions in India. As of the second week of July 2021, 40,845 cases of mucormycosis have been reported in India, and 31,344 (76.7%) of these are rhino cerebral. [4] Mucormycosis of the mandibular region is unusual (Table 1), and to the best of our knowledge, no cases of COVID associated mandibular mucormycosis have been reported to date. Herein, we report three patients who presented with the covid associated mandibular mucormycosis.

Table 1 The list of articles found in literature with mandibular mucormycosis. Ours is the first, Covid associated mandibular mucormycosis (CAMM). Adapted form Agarwal et al. 2020
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Case 1

A 60-year-old male diabetic patient presented with pain and loosening of teeth 5 days following recovery from COVID-19. He was admitted to the general ward under oxygen support for 3 weeks with mild to moderate symptoms of COVID. He had received a single dose of Tocilizumab and injectable dexamethasone over 15 days of his hospital stay.

Case 2

A 48-year-old male, the non-diabetic patient, had pain, pus discharge, and tooth mobility 1-week post covid. He was admitted to the hospital with oxygen support and treated with steroid therapy (Tab Dexamethasone) for 2 weeks. The patient was developed diabetes post covid.

Case 3

A 29-year female patient presented with gingival inflammation, pain, and tooth mobility 6 weeks after recovery from covid. She was a known case of diabetes mellitus and was on insulin therapy. The patient was admitted to the ICU 3 days after onset of COVID-19 symptoms and received a single dose of Tocilizumab and Injectable dexamethasone over 14 days of ICU admission.

All the patients had undergone extraction of offending tooth and the adjacent necrotic bony specimen was sent for calcofluor potassium hydroxide mount (KOH), which was positive for broad pauciseptate hyphae (Fig. 1).

Fig. 1
figure 1

a Photo showing involvement of the molar and premolar region of the alveolus of case 2, b Per-operative photo showing blackish areas of fungal involvement along the inferior alveolar canal case 2, c Pre-operative CT scan of case 2 with 3D reconstruction showing limited mandibular involvement, d Post-operative CT scan of case 2 with 3D reconstruction of the hemimandible and condylar process of the left side, e Pre-operative CT scan of case 1 with 3D reconstruction showing involvement of the molar region of the alveolus, f Post-operative CT scan of case 1 with 3D reconstruction showing excision of a much larger portion of the mandible along with reconstruction, g and h Calcofluor KOH mount showing broad aseptate hyphae with perpendicular branching suggestive of mucormycosis

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Discussions

The consensus for the management of mucormycosis is surgical debridement with antifungal therapy and control of the underlying disease [3,4,5,6].

In two (Case 1 and 2) patients, both, extraoral submandibular and intraoral vestibular approach was adopted whereas, in case 3 surgical site exposure done through intraoral approach. The offending bone was resected until the healthy bone was encountered, as evidenced by bleeding edges. While imaging demonstrated the involvement of a segment of the mandible, we found a much larger involvement in two cases (Case 1 and 2) during resection. There was intramedullary spread of the mucormycosis throughout the entire course of the inferior alveolar canal with pus discharge and foul odor. In routine a CT scan is used for assessing disease extent, but the true extent of the disease in the mandible will be evident only during surgery. In Case 1, both sides of the mandible were involved sparing only the right condyle and ramus, while in the second patient (Case 2), only one side of the mandible was involved sparing the condyle head. In both cases, the radiological extent of the pathology was different from the definite clinical extension of the lesion. This concealing nature of the pathology can be alarming, causing mismanagement of mandibular mucormycosis. Immediate bony reconstruction is debatable and should be deferred to a later date in cases of extensive mucormycosis [2]. In the two cases (Case 1 and 2), reconstruction of the defect was done using a titanium plate (2.8 mm) and screws that were pre-bent according to the contour of the bone. In case 1, the condylar replacement was done using a condylar implant (Stryker® India). However, in Case 3, lingual cortical bone and lower border of the mandible were spared.

The management of covid associated mandibular mucormycosis is challenging, especially because the radiology may not correlate with the actual extent of disease. Surgical planning needs to have a foreseeable leeway for modification based on the bone's clinical extension or osteomyelitic changes. Patient counselling and planning for reconstruction should be kept flexible, and the patients should be involved in every part of planning during surgery. A mountain of clinical disease may hide behind a molehill of radiological evidence.

Conclusion

Thus, the authors recommend an open mind and an eagle's eye to take a radical decision on resection margins and a flexible plan for the reconstruction of the defect to restore functional rehabilitation.