mucormycosis , also known as zygomycosis , is an opportunistic and lethal mycological infection caused by a fungus of the order mucorales . it is mostly observed in immunocompromised patients such as those with hematological malignancy or those who have solid organ transplantation ( sot ) or bone marrow transplants . the infection usually starts in the middle nasal meatus and spreads to the paranasal sinuses , the orbit and the intracranial structures by direct extension or through blood vessels . early diagnosis , initiating prompt surgical and medical therapy and correcting the underlying conditions play a vital role in eliminating this infection , but mortality remains high . mucormycosis is uncommon in sot recipients and most cases have been reported after liver or renal transplantation . a 52-year - old male patient was transferred to our department from another center for retroorbital pain , headache and decreased vision accuracy in the left eye for the past 36 h. five months earlier , he had undergone orthotopic heart transplantation under the bicaval technique due to ischemic heart failure . his medical history was significant for type ii diabetes mellitus , poorly controlled by insulin . he also had hypertension and dyslipidemia ( both under treatment ) and nondialysis - dependent chronic kidney disease . his baseline immunosuppressive regimen consisted of prednisone , tacrolimus and mycophenolic acid and he was also taking prophylactic antibiotics : cotrimoxazole , valganciclovir and isoniazid with pyridoxine . physical examination on admission showed that the patient was alert , orientated , afebrile and his vital signs were stable . anterior rhinoscopy , endoscopy with 0 rigid endoscope and examination of the oral cavity were unremarkable . although the nasal exploration was normal , in view of the symptoms and the previous transplant , two samples endoscopically directed , one of the nasal fossa by swabbing and the second of the middle meatus were collected . blood tests showed glucose levels of 248 mg / dl ( 13.8 mmol / l ) and creatinine of 3.63 mg / dl . computed tomography ( ct ) scan revealed soft tissue opacification of left anterior ethmoid sinus and inflammatory changes in the apex of the left orbit [ figure 1a ] . ( a ) computed tomography scan showed soft tissue opacification of left ethmoid sinus ( white arrows ) and inflammatory changes in the apex of the left orbit ( black arrows ) . ( b ) fundus of the left eye with edema and papillary pallor ( * ) , posterior pole retinal edema ( white arrows ) and arteriolar sclerosis ( black arrows ) . ( c ) left nasal endoscopy with 0 rigid endoscope , showing black necrotic eschar ( white arrows ) through the left middle meatus and the middle turbinate ( black arrows ) . nasal septum ( * ) , ( d ) lactophenol cotton blue culture showing rhizopus fungus . sporangiophore ( black arrow ) ( lactophenol cotton blue stain , x1000 ) the metabolic derangement was treated , intravenous antibiotics ( piperacillin / tazobactam 2000/250 mg 8 hourly ) was started and insulin was administered on a sliding scale . on the second day of hospitalization , the patient 's clinical status worsened dramatically . left eye movements were limited in all directions ( frozen eye ) and the left pupil was mydriatic . signs of central retinal artery occlusion were found on the left fundoscopy : edema and papillary pallor , posterior pole retinal edema and arteriolar sclerosis [ figure 1b ] . a second nasal 0 rigid endoscope showed necrotic tissue in the left middle meatus and the middle turbinate [ figure 1c ] . the lactophenol cotton blue preparation revealed a sporangium located on the columella at the apical end of the sporangiophore [ figure 1d ] . following the confirmation of rm , intravenous liposomal amphotericin b the magnetic resonance imaging showed that infection had progressed in the apex of the left orbit , involving the cavernous sinus . we proposed extensive surgical treatment via left paralateral rhinotomy with orbital exenteration and total ethmoidectomy . its incidence has increased over the last 20 years due to increasing use of immunosuppressive drugs . it appears most frequently in the first 6 months after transplantation due to the higher immunosuppression . the incidence ranges from 0.4% to 16% depending on the sot type and is 0%0.6% in heart transplant recipients . other significant predisposing conditions to mucormycosis in sot recipients are poorly controlled diabetes mellitus and renal failure . the fungus spreads quickly in a medium of elevated glucose and acid ph and it is unusual in patients with metabolically controlled diabetes . the main protection against hyphae is neutrophils , but low serum ph decreases their pathogenic and chemotactic capacity . our patient had three predisposing conditions : immunosuppression for sot , poorly controlled diabetes mellitus and renal failure . three main ways of transmission of mucormycosis in transplant recipients have been reported : inhalation in approximately 70% , ingestion in 2% and percutaneous introduction in 13% . it then extends to the orbit and periorbital area where it can produce the orbital apex syndrome with ophthalmoplegia , ptosis , mydriasis and decreased visual accuracy . finally , it disseminates to the cavernous sinus and then to the meninges and brain . clinical presentation of the disease usually involves symptoms of sinusitis and periorbital cellulitis with facial pain and decreased vision . a nasal endoscopy and a biopsy or a culture of the infected area are essential for the definitive diagnosis . a culture gives us more information about the species of mucorales , but it has a higher rate of false negatives than the biopsy . yohai et al . reported nasal ulceration or necrosis in 48% and 78% respectively in rm . in our case , the initial nasal endoscopy was unremarkable , but we performed a middle meatus culture in view of the high suspicion of rm and the culture revealed a fungus of the order mucorales . the contrast - enhanced sinus ct is helpful to delimit the extension of rm and reveal signs of invasion . magnetic resonance is more sensitive than ct to evaluate intradural and intracranial involvement , the cavernous sinus thrombosis and thrombosis of the cavernous portions of the internal carotid artery . radical resection removing all necrotic tissue should be done and various debridements are usually required . lateral rhinotomy , orbital exenteration and occasionally intracranial surgery are performed depending on the extension of rm . orbital exenteration is necessary when the orbit is infected with limited eye movements in all directions ( frozen eye ) and loss of vision . the surgery that we proposed to our patient was a left paralateral rhinotomy with orbital exenteration and total ethmoidectomy removing all the unviable tissue . amphotericin b is the drug of selection , but it is limited because of its renal and systemic toxic effect . this lipid formulation improves circulation time and concentration in the infected area of the associated amphotericin b. the duration of the treatment is not explicitly established . survival rates in diabetic patients with rm are higher than those in patients with other predisposing factors such as renal failure , hematologic malignancies or autoimmune diseases . a delay in diagnosis and treatment , brain involvement , hemiparesis , bilateral sinus involvement and facial necrosis is also associated with poor survival . rm is a rare and aggressive fungal infection in heart transplant recipients and carries a high mortality rate .