Successful Treatment of Rhino-Sinus Mucormycosis with Isavuconazole Monotherapy and Surgical Debridement in a Hemato-Oncological Patient

Mucormycosis is a rare but life-threatening fungal infection predominantly affecting immunocompromised patients, including those undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We present a case of a 39-year-old male with relapsed acute myeloid leukemia (AML) who developed rhino-sinus mucormycosis after a second allo-HSCT. Initial symptoms included fever, necrotic gingival lesions, and sinus opacification extending into the retromaxillozygomatic space. Rhizomucor variabilis was identified from a biopsy, showing in vitro resistance to azoles but sensitivity to amphotericin B. Given the potential nephrotoxicity of amphotericin B in the context of concurrent cyclosporine A use, isavuconazole was chosen as first-line antifungal therapy despite reported resistance. The patient also required management for pneumonia and sepsis caused by Enterobacter hormaechei and Stenotrophomonas maltophilia, successfully treated with antibiotics and granulocyte colony-stimulating factor. Surgical debridement via functional endoscopic sinus surgery (FESS) was delayed until hematologic recovery, ensuring safe and effective intervention. Isavuconazole treatment, combined with surgery, resulted in significant clinical improvement and resolution of mucormycosis. However, five months post-transplant, the patient relapsed with AML, leading to palliative care initiation. Antifungal therapy was continued with posaconazole, and no recurrence of mucormycosis was observed. This case underscores the challenges of managing mucormycosis in post-allo-HSCT patients, highlighting the importance of individualized therapeutic strategies. Despite in vitro resistance, isavuconazole demonstrated clinical efficacy and safety.