Mucormycosis is a serious, relatively uncommon invasive fungal infection and one of the most aggressive and lethal invasive mycoses [5]. The predisposing factors for mucormycosis are uncontrolled diabetes (particularly in patients having ketoacidosis), malignancies such as lymphomas and leukemias, renal failure, organ transplant, immunosuppressive therapy, cirrhosis, and AIDS [6]. Mucorales species are vasotropic, causing tissue infarctions, and the mucormycosis spectrum ranges from cutaneous, rhinocerebral, and sinopulmonary to disseminated and frequently fatal infections, especially in immune-compromised hosts [7]. Reports have suggested that the ability of serum of immuno-compromised patients to inhibit Rhizopus invitro is reduced, which makes them suitable hosts to opportunistic fungal infections [8]. In diabetic patients, especially with elevated blood sugar levels, the spores germinate, hypae develop, fungi begin an inexorable march through the tissues as blood vessels become involved, thrombosis occurs, resulting in tissue necrosis and fungi continue to grow in this devitalised tissue causing further damage to surrounding tissues [9]. The presence of chronic diabetes in our patient too led to necrosis of palate. Rhinocerebral mucormycosis (ROCM) is the most common form of mucormycosis in patients with diabetes mellitus. The infection develops after inhalation of fungal sporangiospores into the paranasal sinuses. Upon germination, the invading fungus may spread inferiorly to invade the palate, posteriorly to invade the sphenoid sinus, laterally into the cavernous sinus to involve the orbits or cranially to invade the brain which can prove fatal [10]. Our patient had uncontrolled diabetes which is a well-known predisposing factor for mucormycosis along with spread of lesion from the palate into adjacent tissues. The initial symptoms of ROCM are consistent with those of sinusitis and periorbital cellulitis and include eye and/or facial pain and facial numbness followed by blurry vision [5, 10]. Signs and symptoms that suggest mucormycosis in susceptible individuals include, unilateral periorbital facial pain, facial cellulitis, orbital inflammation, eyelid edema, proptosis, acute ocular motility changes, nasal discharge, nasal stuffiness headacheand acute vision loss [5]. If blood supply to eye is affected by invasion of retinal artery, blindness develops. A black necrotic eschar is the hallmark of mucormycosis [12, 13].

Among the differential diagnosis, rhinocerebral mucormycosis may initially resemble bacterial sinusitis and may mimic malignancy. Rhinocerebral mucormycosis may be confused with allergic fungal sinusitis, which is caused by phaeohyphomycoses in individuals with histories of allergic rhinitis, elevated immunoglobulin E levels, nasal polyps and recurrent or chronic sinusitis. Allergic fungal sinusitis slowly progresses over months to years, although it causes proptosis and a large rhinocerebral mass, it does not invade tissue or meninges. Aspergillosis can cause a similar disease, with CNS invasion, and carries a poor prognosis. An important difference is that itraconazole may play a role in treatment. Histologic staining can differentiate between the fungi [15]. The pleiotropic clinical manifestations with other lesions were ruled out with radiographic and histopathology report. A definitive diagnosis of mucormycosis can be made by tissue biopsy that identifies the characteristic hyphae. In order to differentiate histopathologically from other types of lesions such as aspergillosis, which shows presence of narrow, septae hypae with narrow angle branching was done. In this case, the fungus was identified by hematoxylin and eosin stain.

Treatments of mucormycosis need to be fast and aggressive because by the time even the presumptive diagnosis is made, often the patient has suffered significant tissue damage that cannot be reversed. Most patients require both surgical and medical treatments. The line of treatment for such cases requires aggressive surgical debridement of the infected area; otherwise, the patient is likely to die. Medications also plays an important role. Two main goals are sought at the same time: antifungal medications to slow or halt fungal spread and medications to treat any debilitating underlying diseases. Amphotericin B (initially intravenous) is the usual drug of choice for antifungal treatment. Patients with underlying diseases like diabetes need their diabetes optimally controlled. Patients may need additional surgeries and usually need antifungal therapy for an extended time period (weeks to months) depending on the severity of the disease [15]. The prognosis of mucormycosis is usually fair to poor; the prognosis depends on the overall health of the patient, the speed of diagnosis and treatment, the patient's ability to respond to treatments and the complete debridement of the infected body area. In this patient, the line of treatment advised was aggressive surgical debridement of the infected area along with administration of amphotericin B as it is the drug of choice in treatment of mucormycotic infection [2, 6, 11]. The patient was under observation for his ability to respond to treatment due to old age and overall health of patient.

Mucormycosis is a serious, relatively uncommon invasive fungal infection. Early diagnosis is essential because by the time even the presumptive diagnosis is made, often the patient has suffered significant tissue damage that cannot be reversed. The pleiotropic clinical manifestations and elusive presentation of mucormycosis often delay diagnosis, with resultant poor outcomes. Timely diagnosis is critical to survival and minimization of morbidity. Institution of surgical and medical therapy is critical in maximizing the likelihood of good outcome.