Invasive Aspergillus fumigatus Sinusitis as a Mucormycosis Mimic in a Liver Transplant Recipient.

Invasive fungal sinusitis is a serious infection in immunocompromised patients, and distinguishing Aspergillus from Mucorales is diagnostically challenging but clinically critical, as the two organisms require markedly different treatment. A 56-year-old man with alcohol-related cirrhosis status post orthotopic liver transplantation, maintained on tacrolimus and prednisone with well-controlled type 2 diabetes, presented with progressive left facial pain, numbness, and swelling. Despite evaluation by otolaryngology, dental extraction, and antibiotic therapy, his symptoms worsened. Initial imaging was non-diagnostic, and invasive fungal sinusitis was suspected, with mucormycosis considered most likely given his immunosuppression and diabetes. However, surgical biopsy and culture ultimately revealed Aspergillus fumigatus. He underwent surgical debridement and was treated with liposomal amphotericin B followed by oral posaconazole, with improvement in swelling, though residual facial numbness and dental pain persisted. This case illustrates the diagnostic challenge of invasive fungal sinusitis in transplant recipients, in whom Aspergillus can closely mimic mucormycosis on imaging and frozen section. Clinicians should maintain a broad differential for facial pain in immunocompromised patients to optimize outcomes.