Fungal Necrotizing Fasciitis of Craniofacial Region: A Diagnostic Challenge

Abstract

Necrotizing fasciitis is a rare rapidly progressive, devastating surgical emergency that results in necrosis of superficial fascia, and subcutaneous tissue. It most commonly affects the abdominal wall, extremities and perineum, while the involvement in the head and neck region is relatively rare. Here, we report a successfully treated case of necrotizing fasciitis of the craniofacial region caused by Mucor in an uncontrolled diabetic patient. Early diagnosis, early surgical intervention with radical excision of infected tissue, management of underlying predisposing medical condition and supportive therapy (antimicrobials, rehydration, proper rest and nutrition) can reduce the morbidity and mortality associated with this condition.

Introduction

Necrotizing fasciitis (NF) is a rare rapidly progressive, devastating surgical emergency that results in necrosis of superficial fascia, and subcutaneous tissue. Later stages of the disease may occasionally involve the underlying muscle and skin. It most commonly affects the abdominal wall, extremities and perineum, while the involvement in the head and neck region is relatively rare. NF in the head and neck region is primarily due to odontogenic infection, though it may also be secondary to other conditions such as tonsillar or peritonsillar abscess, lymphadenitis, salivary gland and ear infections [1]. Bacterial pathogens (single or polymicrobial) are the main underlying organisms; however, fungi of zygomycetes group may be responsible sometimes in diabetic patients. Only anecdotal reports are there in English literature regarding fungal necrotizing fasciitis of the head and neck region and it poses a great diagnostic dilemma [2, 3]. Because of the rarity, the diagnosis can be missed, leading to unnecessary delay in the treatment, which may be fatal for the patient. Early diagnosis, early surgical intervention with radical excision of infected tissue, management of underlying predisposing medical condition and supportive therapy (antimicrobials, rehydration, proper rest and nutrition) can reduce the morbidity and mortality associated with this condition. The purpose of this paper is to report a case of necrotizing fasciitis of the craniofacial region caused by Mucor in an uncontrolled diabetic patient.

Case Report

A 52-year-old male patient reported with a history of pain and swelling over the right side of the face for the past one week following the toothache. The patient was a known case of diabetes mellitus for the past 6 years and was on oral hypoglycemic.

On examination, he had a fever (38.6 °C), tachycardia and restlessness. Significant facial asymmetry with a diffuse swelling was noted on the right side of face. It was firm, tender and warm on palpation. There was trismus with mouth opening of 20 mm. Mandibular right second premolar and molars were grossly carious, and there was pus discharge from mandibular buccal vestibule. Panoramic X-ray showed impacted 48, grossly decayed 12, 13, 45, 46 and 47.

Initial laboratory investigations showed hemoglobin 8 g/dl, white blood cell count 17.7 × 10⁹/l, sodium 128 mEq/l, creatinine 1.7 mg/dl and random blood sugar 262 mg/dl. Urine was negative for ketone bodies. Viral markers for HIV, HBsAg and HCV were non-reactive.

With a diagnosis of submandibular, buccal and submasseteric space infection of odontogenic origin, extraction of offending teeth along with incision and drainage of the involved spaces was planned. He was started on subcutaneous insulin, empirical broad-spectrum antibiotics (amoxicillin and metronidazole). The extraction of offending teeth followed by incision and drainage of right submandibular, submasseteric and buccal space was carried out, and corrugated drains were placed. 15–20 ml of pus was drained and sent for microbiological examination and culture. No bacteria were seen in smear and culture was sterile.

Despite these measures, his condition did not improve and he developed severe pain and swelling in right temporal region with temperature of 39 ^°C over next 12 h. The examination revealed tense and edematous swelling with crepitus in right temporoparietal, cheek and the submandibular region. Computed tomography (CT) showed extensive cellulitis, multiple air foci and pockets in the right submasseteric space, submandibular space, infratemporal fossa and right temporoparietal region. The right temporalis and masseter muscle was bulky and heterogeneously hypodense (Fig. 1). Based on clinical examination, the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) tool scores [4] and CT scan findings, necrotizing fasciitis was suspected and the patient was taken up for surgery under general anesthesia. LRINEC score in our patient was 8. Aggressive debridement of necrotic fascia, periosteum, oral mucosa, muscle (temporalis, buccinator and masseter) and subcutaneous tissue was carried out via hemicoronal incision with preauricular extension, submandibular incision and buccal vestibular incision (Fig. 2). Ten milliliters foul-smelling dishwater pus was drained. Radical excision of necrotic tissue was carried out until healthy bleeding tissue was encountered; the wound was kept open for serial dressing and debridement.

Fig. 1.

Axial computed tomography scan showing extensive cellulitis, multiple air foci and pockets in the right submasseteric space, submandibular space (a), infratemporal fossa and right temporoparietal region (b). The right temporalis and masseter muscle was bulky and heterogeneously hypodense

Fig. 2.

Intraoperative clinical photographs showing debridement of necrotic tissue via hemicoronal (a) and submandibular (b) incision

The excised necrotic tissue and pus were sent for mycological, bacteriological and histopathological examination. Direct light microscopy in 10% KOH smear was positive for fungal with aseptate hyphae. Histopathological examination showed extensive necrotic tissue infiltration by broad, aseptate hyphae, branched at right angles and confirmed the diagnosis of necrotizing fasciitis with mucormycosis. Bacterial smear and culture were negative with no growth of bacteria in aerobic and anaerobic cultures.

Following confirmation of NF caused by Mucor, he was started on intravenous amphotericin B deoxycholate at the dose of 1.5 mg/kg/day (total dose of 3gm over 1 month). He responded well to amphotericin. He developed mild hypokalemia (k + level 3.4 mEq/l), which was corrected with oral supplementation of potassium chloride (40–60 mEq daily).

Repetitive debridement and dressings were carried out twice daily. Wound closure was done after 18 days once healthy granulation tissue was formed. He was discharged after 1 month in a stable condition and followed up on outpatient basis. The wound completely healed over a period of 2 months, and patient was doing well at follow-up of 18 months (Fig. 3).

Fig. 3.

Postoperative clinical photographs at follow-up of 2 months (a) and 18 months (b)

Discussion

Necrotizing fasciitis of the head and neck region is relatively infrequent, but when does it occur, it can be lethal with a high mortality rate (30%), disastrous morbidity and severe systemic symptoms. The predisposing systemic conditions for NF are diabetes mellitus, malignancy, alcoholism, hypertension and vascular impairment.

Based on causative organism, NF is classified into type I (polymicrobial/synergistic), type II (monomicrobial, usually Gram positive), type III (monomicrobial, usually Gram negative) and type IV (fungal, usually immunocompromised) [5].

Initial signs and symptoms of NF include swelling, erythema, pain and tachycardia. As infection progresses, typical signs and symptoms can be seen including disproportionate pain, tense edema, skin discoloration, necrosis, subcutaneous gas and crepitus. Systemic findings include fever, tachycardia, hypotension and shock [6]. Early diagnosis is the key to a favorable outcome because of the potential fatal course of NF. Clinical signs and diagnostic tools should be used together to make an early diagnosis. Diagnostic tools include: the Laboratory Risk Indicator for Necrotizing Fasciitis created by Wong and colleagues (LRINEC) [4], imaging studies and macroscopic and microscopic examination [6]. LRINEC is based on laboratory variables. LRINEC is a great tool for differentiation of cellulitis and NF, as well as for both confirming and discarding the diagnosis of NF. Among imaging ultrasonography, CT scan and MRI can be used to see specific changes such as increased thickness of fascial layer, another source of infection, deep temporal abscess cavities, gas and other additional anatomical information. Macroscopic findings consistent with NF include gray necrotic tissue, lack of bleeding, dishwater pus and lack of resistance to finger dissection.

Microscopic examination is an important diagnostic tool to detect the causative organism responsible for NF (bacterial or fungal). As fungal NF clinically can present with similar signs and symptoms to that of bacterial NF and diagnosis can be missed. The only way to make a definite diagnosis of causative organisms of NF (fungal or bacterial) is by performing microbiological and histopathological examination. A prompt definitive diagnosis of fungal NF can be made by direct microscopy under light microscopy in 10% KOH and histopathological examination following PAS and H&E staining by identifying characteristic hyphae. Fungal culture can be useful in identifying the causative fungal species but is not sensitive and time-consuming or can increase the mortality rate by delay in diagnosis and intervention [7, 8].

Necrotizing fasciitis of the head and neck region is mainly caused by bacteria streptococci and staphylococci, while very rarely it is caused or complicated by a fungal pathogen [8]. As seen in our patient, there was no growth of bacteria in anaerobic and aerobic cultures. Mucormycosis was diagnosed by fungal smear and histopathological examination. Mucormycosis or zygomycosis is an opportunistic infection and is known to be a disease of immunocompromised patients with higher prevalence in diabetic patients. The predisposing factor in patient was diabetes mellitus that increased the suspicion of a fungal etiology. As in diabetes, acidic environment disrupts iron binding of transferrin which increases the proportion of free iron ions and promotes the growth of fungus and its virulence. Hyperglycemia also contributes to the risk of mucormycosis due to its association with decreased neutrophil chemotaxis and phagocytosis [2, 8]. Recommended treatment for NF with mucormycosis is aggressive debridement and systemic antifungal therapy 1–1.5 mg/kg/day along with correction of the underlying systemic condition. The patient responded well with the relief of symptoms after antifungal therapy points to a fungal etiology. Lipid formulation of amphotericin B is less nephrotoxic with a dosage of 3–5 mg/kg/day [9]. Nephrotoxic nature of amphotericin requires regular monitoring of renal function, serum electrolytes including magnesium and potassium. Hypokalemia and hypomagnesia are common complications in patients receiving amphotericin B deoxycholate for more than 10 days. Hypokalemia and hypomagnesia are corrected by oral or intravenous supplementation depending upon the severity [10]. In cases where patients are intolerant of conventional polyene antifungal treatment, posaconazole is available with a success rate of up to 80% [7, 11]. Antifungal therapy for mucormycosis should be continued until resolution of clinical and radiographic signs of the disease.

The present case was a known diabetic with poor hypoglycemic control and has not responded to the broad-spectrum antibiotic therapy. No bacteria were seen in the smear and bacterial culture. Progression of the disease, absence of bacterial etiology and immunocompromised status of the patient made us think of the possibility of the fungal infection. Rapid diagnosis of fungal pathogen was made by direct microscopy of necrotic tissue under light microscopy in 10% KOH. Definite diagnosis of NF with mucormycosis was made by histopathological examination of the biopsy sample, which made an early intervention with antifungal therapy possible.

Conclusion

The prevalence of mucormycosis of the head and neck region is increasing and is clinically the close mimicker of the bacterial NF. The only way to make a definite diagnosis of the fungal pathogen is by fungal smear and histopathological examination. Missed diagnosis or delay can be fatal to the patient. Therefore, the tissue sample must be sent for fungal smear and histopathological examination in all cases of necrotizing fasciitis. Early diagnosis, prompt antifungal therapy and extensive radical excision of necrotic tissue along with correction of the underlying medical condition are the keys of successful management for fungal necrotizing fasciitis.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.