Role of histopathology in severity assessments of post-COVID-19 rhino-orbital cerebral mucormycosis - A case-control study

Abstract

Background: There was an upsurge in rhino-orbital-cerebral mucormycosis (ROCM) during the second wave of the COVID-19 pandemic in India. Histopathological examination of the biopsies witnessed greater tissue invasion in these cases. The present study aimed to evaluate the histopathological scoring system in the severity assessment and to compare the scores between ROCM that required orbital exenteration (cases) and those that were treated conservatively (controls).

Material and methods: A retrospective study was conducted to analyze the histopathological features using a scoring system in patients diagnosed with mucormycosis on sino nasal biopsies. The scoring was based on the following parameters: the extent of necrosis (score 1 <50% and score 2 >50%), degree of angioinvasion (score 1 <3 vessels in 10 fields and score 2 > 3 vessels in 10 fields), degree of inflammation (mild, moderate or severe), and fungal load(score 1 to 4), based on which three grades (I to III) were given. The scores were compared between the case group and the control group. The data obtained were analyzed statistically.

Results: The study included 40 controls and 10 cases. The median age of patients in the control group was 52 with 82.5%males (n = 43) and 17.5 % females (n = 7) while in the case group, the median age was 51 years, and all were males. The predominant inflammatory response was of mixed suppurative type (70 %, n = 28). The degree of necrosis was scored 2 in 57.5 % (n = 23) of controls and 70 %(n = 7) in the case group. All the samples in the case group showed scores of 2 for angioinvasion and scores of 3 and 4 for fungal load. There was a statistically significant difference in the degree of necrosis, angioinvasion, the severity of neutrophilic infiltrates, and fungal load between the cases and controls (p-value <0.05).

Conclusion: The present study analyses the predictive role of histopathology in invasive mucormycosis. Higher fungal load, degree of angioinvasion, and the absence of granulomas are associated with advanced disease in sinonasal mucormycosis. The study findings recommend incorporating the histopathological scoring criteria in evaluating patients with sinonasal mucormycosis.

Keywords: Angioinvasive; Histopathology; Mixed fungi; Post-COVID-19 mucormycosis; Rhino-orbital-cerebral mucormycosis.