Rhinocerebral Mucormycosis: Battling the alien within

Rhinocerebral mucormycosis (RCM) is one of those entities that you really, really don’t want your patients to have. I have seen a few patients die within hours of the diagnosis.

Mucormycosis is an invasive fungal infection (Rhizopus oryzae) that affects almost exclusively patients with uncontrolled diabetes, immunosuppression or with active malignancies. The pathophysiology is not completely understood, but involves the inhalation of soil spores, nesting the in sinuses mucosa and rapid growth. The mechanism allowing the transformation into an invasive infection appears to require elevated glucose levels, acidosis and iron overload; in other words, an immunocompromised patient with DKA is the perfect host for the invasion.

The initial presentation can be difficult to distinguish from a more benign entity such as sinusitis, however the presentation is severe and the progression of the disease is typically very fast with evidence of invasion outside the nasal cavity (palate), commonly followed by systemic deterioration and neurological symptoms, altered mental status and nerve palsies. A severe or rapidly progressing sinusitis in predisposed patient should raise the alarm of rhinocerebral mucormycosis and warrant aggressive diagnosis and management.

Imaging of the sinus cavities, including CT and MRI, can be relatively normal or non-specific in early stages of the disease and led to false sense of being rule out the disease. Regular laboratory evaluation is of the scant help in making the diagnosis. When suspicion of RCM is high, a nasopharyngeal endoscopic evaluation is strongly recommended.

The endoscopic evaluation will usually reveal blackish necrotic lesions that are almost pathognomonic of invasive RCM. Tissue specimens should ideally be obtained and samples sent for cultures, identification (broad, irregularly branched and few septations) and PCR testing. Assistance from Ear, Nose and Throat physicians as well as Infectious Disease specialists is advised.

The cornerstones for the treatment of RCM are aggressive supportive management, wide surgical excision and debridement and the use of antifungals.

Every effort to support the hemodynamics, improve acid-base status and correct hyperglycemia should be taken. Early involvement of facial surgeons is critical as the removal of the affected tissue is necessary for aborting the invasive process; commonly the surgery will include removal of palate and the orbit.

The pharmacotherapy of choice for RCM is intravenous lipid based amphotericin B and should be initiated as soon as possible. There is some evidence of using a combination of amphotericin B and caspofungin as the first line, but there is no consensus among specialists.

Although the outcomes of RCM are very poor, especially when brain invasion have occurred, if the infection is diagnosed early (when limited to the sinuses) and treatment is initiated promptly, there is a 25-50% chance of survival.

References

• Sun H-Y, Singh N. Mucormycosis: its contemporary face and management strategies. The Lancet Infectious Diseases. 2011 Apr;11(4):301–11.
• Martín-Moro JG, Calleja JM, García MB, Carretero JL, Rodríguez JG. Rhinoorbitocerebral mucormycosis: A case report and literature review. Med Oral Patol Oral Cir Bucal. 2008;13(12):E792–5.
• Cox, GM. Mucormycosis (zygomycosis). In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on March 10, 2015.)
• Kontoyiannis DP, Lewis RE. How I treat mucormycosis. Blood. 2011 Aug 4;118(5):1216–24.

Images

• Mucormycosis in palate from Verma A, et al. Necrosis of maxilla, nasal, and frontal bone secondary to extensive rhino-cerebral mucormycosis. Natl J Maxillofac Surg. 2013 Jul;4(2):249-51. doi: 10.4103/0975-5950.127663. PubMed PMID: 24665188; PubMed Central PMCID: PMC3961907
• Facehugger by r h in Flickr used under creative commons license 1.0