Histopathological Detection of Post-COVID-19 Fungal Co-infection in the Respiratory Tract

Background: Invasive fungal infections can complicate the clinical course of COVID-19, especially in severely ill patients who require admission to the intensive care unit. Objective: To evaluate the histopathological features and severity score of post-COVID-19 fungal co-infection in the respiratory tract in Ninevah Province and correlate the result with age, sex, and diabetes. Methods: Thirty patients who presented with post-COVID-19 fungal co-infection from August to May 2022 were involved in this retrospective case series study. Hematoxylin/eosin stain and periodic acid Schiff stain were used to stain the biopsies. Disease severity was assessed using a scoring system that incorporated grades from I to III across multiple histological variables. Results: Mucormycosis is the only fungal infection found in the samples received, with female predominance and an age of 54.20 years. Perinasal facial pain and swelling were the most common clinical presentations, and 76.7% were diabetics. Necrosis of ≥ 50% was observed in 63.3% of cases with a severe degree of neutrophilic infiltrate, and angioinvasion in more than 3 vessels in 10 high-power fields was identified in 60% of cases. Histologically, grade II was found in 50% of the cases. Conclusions: Post-COVID-19 patients have a significant risk of mucormycosis, in which diabetes and steroid administration were the most important predisposing factors in addition to systemic immune alteration in COVID-19-infected patients. Acute inflammation, tissue necrosis, fungal load, and angioinvasion were proposed.