From the Guidelines
Rhizopus necrotizing sinusitis requires immediate aggressive treatment with urgent surgical debridement and high-dose liposomal amphotericin B at 5-10 mg/kg/day intravenously, as recommended by the most recent guidelines 1.
Key Considerations
- The treatment approach should be initiated immediately upon suspicion, even before definitive diagnosis, to improve survival and reduce morbidity.
- Following initial stabilization, patients can transition to oral posaconazole 300 mg daily or isavuconazole 200 mg daily for at least 3-6 months, as these triazoles are recommended with moderate strength for the treatment of mucormycosis 1.
- Blood glucose control is essential, particularly in diabetic patients, as hyperglycemia promotes fungal growth, and reversal of underlying immunosuppression when possible is crucial for treatment success.
- The infection carries a high mortality rate due to the fungus's ability to rapidly invade blood vessels, causing tissue necrosis and thrombosis, and diagnosis is confirmed through tissue biopsy showing broad, ribbon-like aseptate hyphae with right-angle branching.
Treatment Details
- Liposomal amphotericin B is the first-line treatment, with a recommended dose of 5-10 mg/kg/day intravenously, as it has been shown to have a positive predictive value for survival and time to commencement associated with survival 1.
- Posaconazole and isavuconazole are recommended as salvage treatments, with posaconazole covering Mucorales, including Rhizopus species 1.
- The treatment should be guided by the most recent guidelines, which emphasize the importance of early diagnosis, urgent surgical intervention, and high-dose antifungal therapy to improve prognosis 1.
Monitoring and Follow-up
- Patients require close monitoring with serial imaging and endoscopic examinations to assess treatment response and need for additional debridement.
- The hallmark black necrotic lesions result from vascular invasion, and patients should be closely monitored for signs of disease progression or treatment failure.
- The management of mucormycosis depends on recognizing disease patterns and early diagnosis, and limited availability of contemporary treatments burdens patients in low and middle-income settings 1.
From the FDA Drug Label
Amphotericin B for Injection USP is specifically intended to treat potentially life-threatening fungal infections: ... zygomycosis including mucormycosis due to susceptible species of the genera Absidia, Mucor and Rhizopus...
- Rhizopus necrotizing sinusitis is a type of zygomycosis (also known as mucormycosis) caused by the genus Rhizopus.
- Amphotericin B (IV) is indicated for the treatment of zygomycosis, including mucormycosis due to Rhizopus.
- Therefore, amphotericin B (IV) may be used to treat Rhizopus necrotizing sinusitis 2.
From the Research
Rhizopus Necrotizing Sinusitis
- Rhizopus necrotizing sinusitis is a rare but potentially fatal opportunistic infection caused by Mucorales, specifically Rhizopus species 3.
- The infection can cause severe damage to the nasal cavity and paranasal sinuses, and may invade adjacent vessels and soft/hard tissues 4.
- Rhizopus species, such as Rhizopus arrhizus, are commonly associated with acute invasive fungal rhinosinusitis and chronic granulomatous fungal rhinosinusitis 5.
Treatment and Management
- Successful treatment of Rhizopus necrotizing sinusitis often requires aggressive surgical debridement and antifungal therapy, including liposomal amphotericin B and posaconazole 3, 5.
- Posaconazole has been shown to be effective against Rhizopus oryzae infection in a silkworm model, and may be a useful treatment option for mucormycosis caused by this species 6.
- Allergic fungal rhinosinusitis (AFRS) caused by Rhizopus oryzae has been reported, and may require a combination of surgical and antifungal treatment 7.
Diagnosis and Imaging
- Computed tomography (CT) and magnetic resonance imaging (MRI) may be used to diagnose Rhizopus necrotizing sinusitis, and may show signs of aggressive infection such as loss of calcification of the nasal septum 4.
- The "Vanishing Nasal Septum" sign on CT may be a reliable tool for identifying locally aggressive cases of invasive fungal infections of the nasal cavity at an earlier stage 4.