Histomorphological features of mucormycosis with rise and fall of COVID-19 pandemic

Abstract

Introduction: Due to Corona Virus disease -19, India saw a surge of mucormycosis cases, associated with high death rate. India, during the month of May to July 2021 saw a surge of mucormycosis from all states, with close to 50,000 cases just in a span of 3 months.

Objective: To examine the histopathological appearances of rhino-orbital/rhino-maxillary/sino-nasal mucormycosis in the backdrop of the ongoing COVID 19 pandemic.

Material and methods: The study involved analysis of 60 biopsy samples of suspected rhino-maxillary /rhino-orbital mucormycosis received from post-COVID-19 patients. A preliminary review of the slides showing hyphal forms of fungal organisms with un-doubtful tissue / mucosal invasion was included. All samples were examined under Hematoxylin and Eosin stains along with special fungal stains. Data thus obtained were analyzed statistically. Special stains for fungus namely Periodic Acidic Schiff (PAS) and Gomori Methenamine silver (GMS) were utilized to confirm and/or to differentiate the fungal organisms and to highlight the cell wall of the fungus.

Results: The mean age of the patients with mucormycosis was 51.68 years and 72 (83.33%) of them were males. Acute type of inflammation was noted in 44 (73.33%), granulomatous inflammation in 14 (23.33%) of cases. Bony invasion and perineural invasion was observed in 5 (8.33%) and 55 (91.67%) cases, respectively. The dominant fungus were mucorales in 58 (96.67%), aspergillous, along with mucorales in 12 (20%) and combination of mucorales and candida identified in 8 (13.33%) cases.

Conclusion: Besides all the histological appearance of angioinvasion, bone, and soft tissue invasion, a notable aspect was the shift in inflammatory pattern, which was more granulomatous in nature, with a decrease in fungal load correlating with the drop of COVID second wave. This proves that as immunity develops, the host's response to secondary opportunistic infections changes.

Keywords: COVID-19; Mucorales; Mucormycosis / microbiology; Mycoses / complications; SARS-CoV-2.

Fig. 1

Distribution of subjects according to age.

Fig. 2

Distribution of subjects according to gender.

Fig.: 3

Histological findings of mucorales genera. (A)Microscopy sections of nasal mucosa with dense fungal growth by broad aseptate hyphae of mucor and areas of necrosis(B) Angioinvasion by the fungal organisms (indicated by yellow arrow), (haematoxylin-eosin stain, X40). (C) Neural bundle (N) invasion (inset view, x40)& (D) PAS stain & Gomori methenamine silver stain (inset) highlights the fungal organisms, X40. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 4

Cytoplasm of giant cells containing fragmented fungal organism and refractile crystalline bodies (A)Section shows granulomas formed by multinucleate giant cells and a few fragmented fungal organisms (indicated by red arrow). (B) Refractile crystalline bodies (indicated by yellow arrow). (C) Combined infection by mucor & aspergillus. (D)Fruiting bodies with black color pigmentation (haematoxylin-eosin stain, X40). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)