Introduction: Mucormycosis is a rare but life-threatening fungal infection which may affect people with diabetes mellitus. We report a case of diabetic rhino-orbital-cerebral mucormycosis, with the novel complications of haematogenous cerebral spread, and adrenal insufficiency related to posaconazole therapy.

Case: A 44 year old female presented in diabetic ketoacidosis. The BSL was 30.8 mmol/L, ketones 5.8mmol/L, pH 6.90, HCO3 5mmol/L. At presentation there was no rhinorrhoea, facial swelling, headache or fever.

On day 3, the patient developed a tender right-sided facial swelling. CT of the facial bones showed right-sided pansinusitis. Bedside nasoendoscopy revealed only mucosal inflammation. Initial treatment was clindamycin for presumed bacterial sinusitis.

On day 5, an exploration under anaesthesia was performed. Necrotic eschar in the right maxillary sinus was seen with invasion of the right orbital floor. A right medial maxillectomy and anterior ethmoidectomy was performed and IV liposomal amphotericin commenced. Culture of resected tissue grew Rhizopus arrhizus.

On day 6, the patient developed right-sided proptosis, visual loss, restricted eye movements and trigeminal nerve V1 and V2 sensory loss. MRI brain demonstrated right trigeminal nerve enhancement and inferior rectus muscle thickening. A right orbital exenteration and maxillary sinus debridement was performed.

A day 10 MRI brain detected a left lentiform nucleus and thalamus rim enhancing lesion in addition to a cavernous sinus filling defect. Further treatment included anticoagulation, amphoterin soaked gauze for the eye wound, posaconazole (IV then oral) and IV caspofungin. Falling insulin requirements prompted testing for adrenal insufficiency, which was confirmed with short synacthen testing (peak cortisol 422nmol/L). Hydrocortisone replacement was commenced.

Discussion: Cerebral dissemination to contralateral basal ganglia is likely explained by significant fungal angioinvasion followed by fungaemia and subsequent cerebral seeding. Posaconazole may be a cause of adrenal insufficiency secondary to ergosterol synthesis enzyme inhibition. 

Conclusion: Although rare, clinicians must consider mucormycosis infection in patients with decompensated diabetes presenting with sinusitis. Early surgical intervention is vital in the management of this life-threatening infection. This is the first documented evidence that rhino-orbital-cerebral mucormycosis is capable of haematogenous spread. This is also the first report of posaconazole associated adrenal insufficiency outside of the clinical trial arena.