Sinonasal Mucormycosis: A to Z

Abstract

Mucormycosis caused by one of the members of Mucoraceae family, is one of the most rapidly spreading and fatal fungal infection occurring mostly in Diabetic or Immunocompromised patients especially in developing countries. 26 patients suffering from sinonasal mucormycosis admitted in SGRRIM&HS, Dehradun from January 2013 to January 2017 are discussed. Diagnosis of mucormycosis was established on strong clinical suspicion with presence of grayish black crusting on nasal endoscopy which is confirmed by histopathology examination. Immediate correction of underlying immunocompromised status with debridement with intravenous liposomal amphotericin B was done in all the 26 cases out of which 10 patients were cured. Early detection and aggressive multidisciplinary management is must for the successful treatment of mucormycosis.

Introduction

Sinonasal mucormycosis is an acute invasive fungal infection which is rare, opportunistic and potentially fatal, that mostly occurs in immunocompromised patients caused by saprophytic and opportunistic fungi of class Phycomycetes, order mucorales, family mucoraceae belonging to genus mucor and rhizopus [1].

There exists very few ENT conditions which has high mortality rate and mucormycosis is one of them. Without proper treatment, the disease is rapidly fatal in 50–80% of cases [2].

The advancements in medical field have prolonged the survival of patients with hematologic malignancy and diabetes mellitus, consequently increased the risk for developing invasive fungal rhinosinusitis in the population [3]. Thus increasing the prevalence of acute invasive fungal sinusitis secondary to increase in the population of immunocompromised patients [4].

Materials and Methods

26 patients with histopathologically diagnosed with sinonasal mucormycosis from January 2013 to January 2017 were analyzed. Patients were evaluated with detailed history; ENT, ophthalmic and neurological examination. Routine blood investigations were done. Diagnostic nasal endoscopy was done and biopsy was taken. CT scan of Nose and PNS were obtained to assess the extent of the disease. MRI was done to evaluate intraorbital or intracranial extent. Treatment was started for any underlying metabolic disorder. Surgical debridement was done within 24 h and a second look surgery done after 48 h. Once a histopathological diagnosis of mucormycosis was established, amphotericin-B was started. Over 4–6 h a test dose of 1 mg Amphotericin-B in 200 ml of 5% dextrose was given. Every alternate day kidney function and serum electrolytes were monitored. Nasal endoscopy was done daily and gelfoam soaked with Amphotericin-B was kept locally at the surgically debrided area. Follow-up was done every week for first 3 weeks and then every month for 6 months.

Results

Stages of Presentation

Stage	Involvement of	Number of patients
Stage 1	Nose and PNS	6
Stage 2	Nose and PNS with orbital extension	8
Stage 3	Nose, PNS and orbit with intracranial extension	12

Nose and PNS were involved in 6 cases. In 8 cases, there was Orbital involvement along with Nose and PNS while 12 cases had intracranial extension.

Status of Comorbid Conditions

Stage	Comorbid condition	Immunocompromised status
Stage 1 (6 cases)	4 pt with DM 2 pt with long term steroid use	Reversed Reversed (stopped)
Stage 2 (8 cases)	8 pts with DM with DKA	Could be reversed only in 4 cases
Stage 3 (12 cases)	12 pts with DM with DKA	Could not be reversed

The most common co-morbidity was the diabetes mellitus. In stage 1, 4 patients had DM and 2 patients were on prolonged steroid use. In stage 2 and 3, all patients had DM with diabetic ketoacidosis. Immunocompromised status was successfully reversed in all patients in stage 1. In stage 2, it was controlled in only 4 cases and could not be controlled in any patient belonging to stage 3.

Results

Stage	Treatment modality	Recovered	Mortality
Stage 1 (6 cases)	1. Correction of comorbidity 2. Endoscopic debridement with IV amphotericin B	6	0
Stage 2 (8 cases)	1. Correction of comorbidity 2. Endoscopic debridement with IV amphotericin B with orbital exenteration	4	4
Stage 3 (12 cases)	1. Correction of comorbidity 2. Endoscopic debridement with IV amphotericin B	0	12

In stage 1, endoscopic debridement with intravenous liposomal Amphotericin B was given and all the 6 cases were cured. In stage 2, along with endoscopic debridement and intravenous liposomal Amphotericin B, orbital exenteration was done; but only 4 cases could be saved. In stage 3, endoscopic debridement of the disease in nose and PNS was done along with intravenous liposomal Amphotericin B therapy, but none of the patients could be saved.

Discussion

Sinonasal fungal infection is the inflammation of sinonasal mucosa resulting from fungi. It can be Non Invasive (absence of fungal hyphae within the sinus mucosa) and Invasive (presence of fungal hyphae within the sinus mucosa) [5].

1. Non invasive	(a) Fungal ball
	(b) Allergic/eosinophilic fungal rhinosinusitis
2. Invasive	(a) Acute—acute fulminant invasive fungal sinusitis (AFIFS)
	(b) Chronic-immunocompetent and immunocompromised
	(c) Sclerosing
	(d) Granulomatous

Pathogenesis

Mucormycosis is an acute fulminant invasive form of fungal sinusitis [6]. In high risk individuals like patients with

1. Underlying disease: leukemia, lymphoma, neutropenia, diabetes mellitus with or without DKA, acute renal failure

2. Patients on treatment with antineoplastic agents, prolonged corticosteroids, deferoxamine therapy, broad spectrum antibiotics

3. or, patients with burns, extensive trauma or severe malnutrition

There inoculation by inhalation when fungal spores reach the nasal cavity. There germination is favoured by low oxygen concentration, high glucose, acidic medium and high iron levels. They germinate into hyphae [7]. Due to the metabolic hypoxic conditions, the Polymorphonuclear cells are less effective at removing these hyphae, as it is often found in patients with mucormycosis associated with Diabetes mellitus, thereby favouring the establishment of infection [8]. Mucorales grow throughout the internal plate as they have high affinity for the arteries, dissecting it and causing extensive endothelial damage. This consequently results in thrombosis and ischemia leading to gangrene and black necrotic eschar tissue formation [9]. Extension of the disease into the maxillary and ethmoid sinus can lead to orbital involvement. Through the superior orbital fissure, ophthalmic vein and cribriform plate along the perivascular channels can occur the intracranial spread [8].

The host factors which play an important role in establishment of disease are [10]

1. Ketoreductase enzyme: Rhizopus has enzyme Ketoreductase, which allows the fungus to utilize the ketone bodies in the patients. Thus they thrive in acidotic and high glucose environment.

2. Diabetic Ketoacidosis: DKA impairs chemotaxic and phagocytic activity of neutrophils (due to impaired glutathione pathway) and increase in the serum iron level.

3. Decrease in Neutrophil response: The inflammatory response of the body is decreased due to DKA and the local aggregation of granulocyte and fibroblasts is delayed leading to disease formation. The disease occurs mainly in immunocompromised patients in whom the neutrophil response is absent or impaired.

4. Rhizoferrin: Substance Rhizoferrin is produced by the fungal hyphae which binds iron avidly. This iron rhizoferrin complex is then taken back into the fungus and this iron becomes available for vital intracellular process for fungal growth.

5. Pterygopalatine fossa: Some studies have shown that Pterygopalatine fossa acts as a reservoir of the disease and via sphenopalatine foramen acts as a passage for disseminating the infection to the other locations.

Signs and Symptoms

PUO which does not respond to IV broad spectrum antibiotics is a common symptom encountered in patients with mucormycosis. Anaesthesia felt over cheek region or nasal mucosa is an early sign as well as symptom of invasive mucor infection [11]. Thus the presence of anaesthesia should prompt biopsy and culture in at risk patients for mucormycosis, also resolution of anaesthesia may be an important clinical marker of positive response to therapy [12]. Classical finding of black necrotic eschar tissue that resembles dried blood or a purulosanguinous exudates with an unpleasant odour may be observed in the nasal cavity in mucormycosis (Fig. 1a, b). Other symptoms include fever, nasal ulceration or necrosis, discharge from nose, periorbital swelling, altered vision, headache, facial pain, altered mental status, ophthalmoplegia, orbital cellulitis, proptosis and seizures [13].

Fig. 1.

a Black necrotic eschar tissue on nasal endoscopy. b Purulent exudates with an unpleasant odour on nasal endoscopy

Nasal Endoscopy

In these high risk patients, a careful nasal endoscopy with an eye of suspicion can detect an early mucormycosis infection [14]. The change in the normal appearance of the nasal mucosa is the most consistent finding in the nasal endoscopy. Main clinical findings include the black necrotic eschar tissue with underlying purulent exudates with an unpleasant odour [9] (Fig. 1a, b). The presence of white discolouration indicates tissue ischemia which is secondary to angiocentric invasion. In high risk suspected patients, surgeon while performing nasal endoscopy should carefully inspect the common sites for mucormycosis, which includes middle turbinate (67%), septum (24%), palate (19%) and inferior turbinate (10%). If there is decreased mucosal bleeding and/or presence of sensation in these areas, then it may be a sign of fungal disease and a biopsy should be performed [14]. For the timely diagnosis, a biopsy from suspicious area with frozen section in patients with sinusitis and poorly controlled DM should be promptly done [13]. A nasal swab for fungal culture is usually insufficient in evaluation of mucormycosis [14].

Histopathology

The Microbiologist must be informed regarding the purpose of the culture to test for a phycomycotic infection, else, the culture might be discarded by the lab for the fungal contamination [15].

Studies show that initiation of the treatment based on the examination of the frozen section saves the precious time in the control of the disease spread [15].

On histopathology, the fungal hyphae seen were broad, ribbon like, irregular and aseptate with branching at right angle. Submucosal infiltration was present. Fungal growth was evident in Dextrose Sabouraud’s Agar medium. Aseptate broad fungal hyphae were evident with Hematoxylin and Eosin stain. Mucor sporangium with sporangiophore were evident on lactophenol cotton blue staining (Fig. 2a, b, c, d) . Angioinvasion was demonstrated by H & E stain [15] (Fig. 3a, b).

Fig. 2.

a PAS stain showing hyphae with right angle branching. b H & E stain showing aseptate broad fungal hyphae. c Sabouraud Dextrose Agar with chloramphenicol and cycloheximide medium showing fungal growth. d Lactophenol cotton blue stain showing sporangiophore with sporangiophore

Fig. 3.

a, b Haematoxylin and eosin staining showing angioinvasion

CT Scan

CT scan nose and PNS is just supportive and not at all diagnostic but is required to assess the extent of disease and also for planning of surgical management. Thickening evident in periantral fat planes is the earliest imaging sign of fungal rhinosinusitis. MRI is considered more sensitive compared to the CT Scan for detection of the orbital and intracranial involvement [16] (Fig. 4a, b).

Fig. 4.

a CT scan PNS showing minimal disease even in stage 2 case of mucormycosis. b MRI brain showing intracranial disease in stage 3 case

CT Scan

1. Documentation of the presence of disease and demonstration of the exact spread and extent of the disease, especially for surgical management.

2. Demonstration of Anatomical variations which consequently prevents the surgical complications.

3. Aids in monitoring of disease and treatment.

MRI

MRI is considered more sensitive when compared to the CT Scan for detection of the orbital and intracranial extension [16]. MRI may help in the prevention of the unnecessary procedure in patients who are unlikely to benefit from surgery as mortality rate of nearly 100% (has been demonstrated in patients with intracranial extension).

It is done in patients with:

1. suspected intracranial disease

2. change of mental status

3. orbital apex syndrome

4. seizures

5. stroke

6. orbital involvement

Treatment

Treatment of mucormycosis involves a team effort for simultaneously treating the various conditions in a same patient [14] (Fig. 5).

Fig. 5.

Preoperative cases of mucormycosis in various stages

Treatment is divided into [14]:

• I.Prevention of disease
• II.Early prompt diagnosis
• III.Reversal of the immunocompromised status
• IV.Appropriate aggressive surgical debridement
• V.Rapid antifungal therapy

• I.Prevention of Disease

Ideal treatment of fungal rhinosinusitis would be the prevention of the disease in the initial place. Prevention can be done by

1. Decreasing the exposure to the pathogenic fungi

Inhalation of the spores is the main mechanism by which fungi is taken, so the aim should be to decrease the fungal load as well as exposure in hospital premises to decrease hospital associated outbreak. This can be achieved by the regular cleaning of the air ducts, use of the masks, isolation of the construction zones, sealing of windows by keeping high risk patients in isolated special room with laminar airflow and high efficiency particulate air (HEPA) filters.

• 2.By diagnosis and management of rhinosinusitis in patients before scheduled immunosuppressive therapy, if possible

If the existing medical condition allows, patients scheduled for immunosuppression or all high risk patients with sinusitis should be thoroughly screened and if possible should be treated before immunosuppression (Figs. 6, 7).

Fig. 6.

Surgical debridement in a stage 1 case with removed debris

Fig. 7.

Surgical debridement in a stage 2 case with removed orbit

Whenever possible, a detailed history with questionnaire, ENT examination, nasal endoscopy and if required a CT Scan PNS should be done to make early diagnosis in patients before scheduled immunosuppression. Thereafter diagnosis can be made and prophylactic therapy can then be initiated.

• 3.Prevention with prophylactic antifungal therapy

Patients at risk can be considered for prophylactic antifungal therapy for a limited period of time. However the studies have shown that this can result in resistance to antifungal agents. This can be avoided by carefully identifying the patients at highest risk and also limiting the prophylaxis to period of time when the risk is the highest. Drug chosen for this purpose should be safe, well tolerated with minimal toxicity. Very high risk patients include patients with prolonged neutropenia, hematologic malignancies, and the patients undergoing bone marrow transplantation.

• II.Early Diagnosis

A clinician must have a high index of suspicion for managing the at-risk patients though the signs and symptoms are subtle. Pyrexia of unknown origin (PUO) not responding to intravenous broad-spectrum antibiotics and feeling of anaesthesia over cheek or nasal mucosa in high risk patients should always raise suspicion. A thorough nasal endoscopy with a timely biopsy with frozen section helps in early detection of disease. Patients at risk for developing mucormycosis are:

1. Absolute neutrophil count below 500 cells/ml

2. Prolonged steroid use

3. Prolonged antibiotic use

4. Recipients of organ transplantation with sinusitis

The therapeutic decisions made with the frozen sections rather waiting for fixed specimens are related to the improved outcomes in the patients with mucormycosis.

• III.Reversal of underlying disease

All the existing co morbid conditions should be simultaneously and rapidly treated. Immunosuppressive medication, particularly the corticosteroids should be given at low dosage or stopped, if possible.

Surgical Debridement

It

1. Slows down the disease progression and restricts the extent allowing time for bone marrow regeneration.

2. Reduces the fungal load which consequently reduces the load on recovering neutrophils.

3. Provides a specimen for histopathology.

The antifungal agents cannot reach the involved site due to the blood vessel thrombosis and resulting tissue necrosis, consequently surgical debridement is very important for complete control of mucormycosis.

The surgical management has evolved from external open techniques to endoscopic debridement (Fig.6a, b, c) with no increase in mortality and a decrease in morbidity. Intraoperative frozen section is used to delineate the margins of infected tissue and uninvolved tissues are spared from debridement when possible. Surgical excision should be continued until normal, well perfused bleeding tissue is observed. Once debridement is done, local area can be packed with gelfoam soaked in Amphotericin B (50 mg vial of Amphotericin B diluted in 10 ml of sterile water). Second look surgery after 48–72 h is done, weekly nasal endoscopy is done till reversal of neutropenia than over a month for 6 months. Total loss of vision and impending intracranial extension demands orbital exenteration. Care is individualized depending on the extent of orbital involvement. Extensive intracranial extension is a contraindication for surgery as the mortality rate is nearly 100%—it would just increase the morbidity of the patient. Pterygopalatine fossa acts as a reservoir for fungal disease and should be cleaned properly.

• Orbital Exenteration (Fig. 7a, b, c): when to do?

Decision should be individualized based on:

1. Retinal artery involvement

2. Aggressiveness of disease presentation

3. Type of underlying disease process

4. Response to initial therapy

5. Vision of the patient

• IV.Antifungal Therapy

Amphotericin B and Isavuconazole are the two agents approved for primary therapy of mucormycosis. Posaconazole can be used for salvage treatment in patients who are intolerant to Amphotericin B. It can also be used as a step down therapy after initial control of the disease with Amphotericin B. However both posaconazole and specially isavuconazole have an availability problem. Initiation of the polyene therapy within 5 days of diagnosis of mucormycosis was associated with improvement in survival, when compared with initiation of polyene therapy at 6 days or more after diagnosis (83 vs 49% survival).

Amphotericin B Deoxycholate: Polyene Macrolide

The antifungal activity of AmB is due to its ability to bind preferentially to ergosterol, a major component of the fungal cell membrane [17]. Cell membrane permeability then is increased following attachment of this lipophilic structure to the fungal cell wall resulting in the leakage of intracellular components and ultimately cell death. Unfortunately it also binds to a lesser degree to cholesterol in mammalian cell membrane, which explains for its toxic effects on human cells. These include infusion related reactions, electrolyte imbalance, nephrotoxicity, thrombophlebitis.

Infusion related reactions occur in 50% cases. These can be rigor, chills, fever, headache, nausea, malaise and generalized rashes. These can be avoided or minimized by premedication with aspirin or ibuprofen or by adding 25 mg of hydrocortisone to the infusion directly.

Thrombophlebitis: it can be decreased by decreasing the rate of infusion and by adding small amount of heparin to the infusion, rotating the infusion site and by avoiding highly concentrated preparations of AmB (< 0.1 µg/ml).

Nephrotoxicity: occurs in about 80% cases. It is reversible but can be irreversible if high doses of AmB are used. It can be decreased by using Sodium supplementation using normal saline 500 ml to 1 l given before and after infusion and by avoiding any other concomitant use of nephrotoxic drugs and by giving the drug as slow IV diluted infusion with daily monitoring of renal function tests.

Anaemia: can occur in about 35% cases in patients with extended therapy. It occurs due to direct suppression of erythropoietin production consequently decreasing the production of erythrocytes.

Dose: IV dose 0.3–0.7 mg/kg/day in 5% Dextrose solution, with maximum daily dosage of 1.2 mg/kg/day in adults and 1.5 mg/kg/day in children.

Amphotericin B deoxycholate and liposomal Amphotericin B are used for primary treatment of mucormycosis depending on the availability, cost and most importantly the general status of patients as they can cause nephrotoxicity [18] and infusion related reaction Maximum daily dose for Amphotericin B is 1–1.2 mg/kg/day while for the liposomal Amphotericin B is 3–5 mg/kg/day. The dose of Amphotericin B is 1–1.5 mg/kg body weight/day. Test dose to be given is 1 mg in 20 ml of 5% dextrose over 20 min. Therapy is initiated at 0.25–0.30 mg/kg, then the dose is gradually increased by 0.25 mg per day. Total dose is 2.5–3 g. In calculating the dose of liposomal Amphotericin B for infection involving the CNS, the dose is 10 mg/kg/day due to its limited penetration into the brain.

Due to the alteration in ergosterol synthesis due to the effects of the azole compounds leading to decrease in number of potential binding sites on the fungal cell membrane for amphotericin B, there are increasing reports of development of resistance to AmB

Lipid Based Formulations of AmB [19, 20]

1. Amphotericin B Lipid Complex (ABLC): 5 mg/kg/day

2. Amphotericin B Cholesteryl sulfate compound (ABCD): 3–5 mg/kg/day

3. Liposomal Amphotericin B (LAmB): 5–7.5 mg/kg/day

The liposomal Amphotericin B are not as potent as the conventional drug when administered in similar dosages, but the ability to give higher doses improves the therapeutic efficacy of liposomal Amphotericin B. The liposomal Amphotericin B is the drug of choice for intracranial disease as a significant difference in the time needed for the drug to reach CSF. LAmB is the drug of choice for rhinocerebral mucormycosis, which requires administration of high doses of polyenes after surgical debridement. Dose can be increased to 10 mg/kg/day for infection involving the CNS due to limited polyene penetration into the brain.

Isavuconazole (Cresemba)-Triazole [19, 20]

It was approved for the treatment of mucormycosis in 2015 after its use was established in a non comparative, single arm, open label, matched case control study. It inhibits cytochrome P450 dependent 14 alpha lanosterol demethylase.

Dose: 200 mg every 8 h for 6 doses then it is given once a day.

It should be avoided in patients with short QT interval and also coadministration should be avoided along with sodium channel blockers and anti epileptics.

Posaconazole: Azoles [19, 20]

Posaconazole (800 mg/day given in divided doses) is not recommended as primary treatment of mucormycosis, but it is an option for patients who are intolerant to amphotericin B or, who needs prolonged continuation or maintenance therapy.

Flucytosine [19, 20]

A cytosine analogue originally formulated for the use as an antineoplastic agent. The mechanism of action was directly on the RNA and DNA of the yeast cells. Following entry into yeast cells it is converted into the cytoplasm to 5-fluorouracil by a cytosine deaminase and incorporated into RNA, disrupting the genetic code. 5FU is subsequently converted to 5 fluorodeoxyuridine and ultimately inhibits DNA synthesis.

Terbinafine [19, 20]

It is an allylamine compound. It inhibits the enzyme epoxidase, resulting in depletion of ergosterol and ultimately leading to cell death.

Echinocandins: Caspofungin, Anidulafungin, Micafungin [19, 20]

These drugs act by inhibiting 1,3-beta glucan synthesis for the fungal cell wall, a critical component for the maintenance of cell wall integrity. These are not the first line therapy in mucormycosis but can be used as a combination of a polyene and also as in salvage therapy after failure of appropriate first line therapy.

Iron Chelation Therapy: Deferiprone, Deferasirox [19, 20]—20 mg/kg/day for 14 days

Deferamine, an iron chelator acts as a siderophore for mucorales and therefore supplies previously unavailable iron to the fungi and promotes their growth. In contrast, iron chelation by deferasirox/deferiprone that cannot be utilized as siderophore by the mold creates iron deprivation that reduces fungal growth. A deferasirox-Ambisome therapy (DEFEAT Mucor study) is a double blind randomized, placebo controlled, phase 2 safety/exploratory study of adjuvant deferasirox therapy for mucormycosis had a higher mortality rate.

Hyperbaric Oxygen Therapy [21]

It improves the flow of oxygen to the ischemic tissue and alleviates the acidosis, thereby inhibiting the fungal growth. It also boosts the killing capacity of leukocytes by providing the optimal oxygen tension for oxidative burst. Furthermore by correcting the lactic acidosis, treatment with hyperbaric oxygen promotes the oxidative action of amphotericin B.

Proinflammatory Cytokines: GCSF, GMCSF, Interferon Gamma [20]

These can be used in patients with neutropenia as it helps in bone marrow recovery in neutropenic patients leading to better survival rate.

Adjuvant Therapy with iron chelation therapy, hyperbaric oxygen and pro-inflammatory cytokines has been tried, but their efficacy is yet to be confirmed.

Duration of Treatment

It needs to be individualized as per each patient depending on the clinical improvement in sign and symptoms, negative histopathology, normalization of radiography and most importantly recovery from immunosuppression or co-morbid condition.

Monotherapy Versus Combination Therapy

Views are divided, but final decision should be individualized for each patient depending upon the comorbid conditions and availability of other treatment modalities. The benefit of combination therapy compared with monotherapy was most pronounced in patients who had cerebral involvement.

Salvage Therapy [20]

Posaconazole can be used as salvage therapy. Limited clinical data suggest that combination of Lipid formulation of amphotericin B and Echinocandins (caspofungin) may be used as salvage therapy. Other combinations for salvage therapy can be amphotericin B and Posaconazole, amphotericin B and deferasirox or maintenance therapy on posaconazole.

Prognosis

Good prognosis is seen with limited anatomic disease. DM as a co-morbidity has a higher chance of being corrected as compared to immunosuppression caused by haematological malignancy. Early detection and treatment within 5 days with combination therapy gives better results as compared to monotherapy started after 6 days of diagnosis.

Problem Faced

Usually, otolaryngologists are involved by a physician when their patient with DKA deteriorates and is found to have sinusitis. Thus, by the time the patient is first seen, the disease already has extra sinus spread. Most otolaryngologists have low exposure to the disease owing to its rarity. Confirmed histopathological diagnosis consumes some very valuable time. Cost and consent for treatment can sometimes be an issue in certain cases.

Conclusion

Early detection and aggressive multidisciplinary management is a must in the treatment of mucormycosis.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.