Fatal Pharyngeal Cellulitis Caused by Rhizopus microsporus in a Patient with Acute Myeloid Leukemia.

INTRODUCTION: Patients with immunodeficiency are highly susceptible to life-threatening fungal infections. Pharyngeal cellulitis caused by Rhizopus microsporus are exceptionally rare. CASE PRESENTATION: We reported a case of relapsed acute myeloid leukemia (AML) complicated by post-chemotherapy Rhizopus microsporus pharyngeal cellulitis. This cellulitis resulted in severe tissue necrosis, pharyngeal obstruction, and sub-sequent suffocation. Emergency bedside tracheotomy was administered after acute respiratory distress. The metagenomic next-generation sequencing (mNGS) identified Rhizopus microsporus, Klebsiella pneumoniae, Candida albicans, and SARS-CoV-2. Despite surgical intervention and combination antimicrobial therapy (amphotericin B, posaconazole, daptomycin, ceftriaxone, and molnupiravir), the patient stabilized for 2 months before culminating in fatal carotid artery rupture. CONCLUSION: Rhizopus microsporus-related pharyngeal cellulitis is rare yet highly aggressive, demanding timely diagnosis and close monitoring. This case highlights the critical role of rapid mNGS in diagnosing polymicrobial infections, underscores the necessity of combining aggressive surgical debridement with antifungal/antimicrobial regimens, and stresses rigorous surveillance to prevent life-threatening vascular complications.