ⅠINTRODUCTION
Mucormycosis or zygomycosis usually spreads rapidly from the nose and paranasal sinuses, and is considered one of the most lethal forms of rapidly progressing human fungal infections1). This opportunistic infection typically manifests in patients with certain systemic conditions such as uncontrolled diabetes, renal failure, and hematological malignancies. Furthermore, the risk of contracting mucormycosis or zygomycosis increases in immunocompromised patients such as those with acquired immune deficiency syndrome, or those receiving chemotherapy and long term steroids2). Once the fungus invades the arteries, blood supply is reduced due to the formation of thrombi inside the blood vessels, leading to both hard and soft tissue necrosis3,4). Infection first spreads from the upper turbinate or paranasal sinus; it is less likely to initiate in the palate or pharynx5). In this paper, we report a case of mucormycosis that occurred in the maxilla with a review of the literature.
ⅡCASE REPORT
A 75-year-old man with primary complaints of pain and pus discharge from the palatal side of the maxilla was referred to our clinic from another hospital. Due to lung cancer, the patient had previously undergone a pneumonectomy on the left side and had chronic obstructive pulmonary disease. Clinical examination revealed necrotic bone exposure on the right maxillary edentulous and pus discharge in the mid-palatal area (Fig. 1).
Computed tomography (CT) indicated that infection had spread across the maxilla with sequestra formation at the necrotic area separated from the adjacent structure. Sinusitis accompanying the destruction of the bilateral maxillary sinus wall and an air-fluid interface was observed (Fig. 2-A). A bone scan revealed mild tracer uptake (Fig. 2-B). A biopsy was then performed by surgically removing the exposed part of the necrotic bone under local anesthesia. Histologically numerous right-angled branches of the fungal hyphae were observed around the necrotic bone and diagnosed as mucormycosis (Fig. 3). Considering the systemic condition and age of the patient, removal of the whole necrotic maxilla bone was not practicable. Instead, under local anesthesia, both the right and left side exposed necrotic bones were surgically removed at a time (Fig. 4). The patient exhibited favorable healing 6 months postoperatively.
ⅢDISCUSSION
The mucorales fungi can infect an individual through various routes such as inhalation, ingestion, and traumatic inoculation, and can occur in the oral and nasal pharyngeal mucosa of healthy patients. This fungi can be found in moldy bread, soil, and decaying matter, and in infected patients, mucormycosis presents multiple clinical manifestations6. These include cutaneous, gastrointestinal, pulmonary, and disseminated forms; however, rhinocerebral mucormycosis, involving the nose, paranasal sinuses, orbit, and central nervous system, is the most common and has been subclassified into rhinomaxillary and rhinocerebralorital mucormycosis7,8). This report presents a case of rhinomaxillary mucormycosis showing necrotic maxillary bone and the bilateral sinus cavity infection.
Malaise, headache, swelling, facial pain, and mild fever are common clinical symptoms of rhinocerebral mucormycosis. The infection usually initiates in either the nasal mucosa or the palate and spread to the paranasal sinus through the surrounding blood vessels9,10). Similar to that reported in the present case, as our case the patients usually experience facial pain and pus discharge from the mid-palatal area. Alveolar bone exposure and necrosis may also occur.
Mucormycosis typically presents in patients with systemic conditions, such as diabetes, renal failure, lymphoma, leukemia, immunosuppressive therapy, malnutrition, and severe burns, whose immunocompetence appears to be compromised. Approximately 40–50% of patients with mucormycosis have also been shown to have diabetes3,9). Our case patient has no history of diabetes, but the immunocompromised condition due to depressed pulmonary and respiratory function caused by pneumonectomy and old age might influence the outbreak of mucormycosis.
For the detection of mucormycosis, CT is the initial imaging method generally selected. However, CT findings can be non-specific in the early stages of disease; even if a patient is infected with the invasive mucormycosis, they can present a normal sinus on a CT scan. Bone erosion and extra sinus spread are distinct features of mucormycosis and therefore comprise strong evidence for its diagnosis11). Due to high levels of sensitivity, magnetic resonance imaging is typically utilized for the identification of extra sinus spread, especially the invasive soft tissue infection12). In the present case, diagnosis was based on CT and bone scans that revealed necrotic maxilla bone and bilateral maxillary sinus infection. While bone scan show mild tracer uptake at maxilla, there was a limitation in determination of the exact location and boundary of lesion. The diagnosis of mucormycosis through a preoperative biopsy is crucial for the treatment plan.
Mucormycosis is characterized by widespread tissue necrosis and the presence of numerous large (5–30 ㎛) and thin-walled fungal hyphae lacking septa. Hyphae are branched at right angles and exhibit a ribbon-like appearance9,10). These typical histological features of mucormycosis were observed in the present case.
Aggressive treatment to control any underlying predisposing risk factor is the most effective primary medical approach for mucormycosis treatment. Surgical management involving debridement of all infected tissue should be performed early in the treatment process. Radical resection such as partial or total maxillectomy, mandibulectomy, and orbital exenteration may be required during the treatment13,14). Amphotericin B deoxycholate along with its lipid presentation is widely utilized as an antifungal agent for the treatment of mucormycosis due to its low nephrotoxicity11,15). In the present case, amphotericin B deoxycholate was administered following the surgical removal of necrotic maxilla after early diagnosis. While the removal of necrotic maxilla was limited due to the systemic condition of the patient, a relatively adequate healing process was evident 6 months postoperatively. Prognosis of mucormycosis is generally poor; however, its mortality rate decreased from 84% in the 1950s to 40% in the 1990s due to the establishment of early diagnosis and multimodal therapy. Multimodal therapy includes the alleviation of immunocompromised status, reversal of intrinsic risk factors, rapid and aggressive antifungal therapy, and, most importantly, surgical debridement5,6,16).
In conclusion, we report a case of mucormycosis in the maxilla. Immunocompromised patient status due to old age and respiratory dysfunction caused by pneumonectomy appeared to influence the onset of mucormycosis in this case. We performed CT imaging, bone scanning, and an incisional biopsy to establish an initial diagnosis. Based on an early diagnosis, we were able to obtain favorable outcomes through the surgical removal of necrotic bone and the administration of amphotericin B deoxycholate.
