Mucormycosis and Zygomycosis: Maxillary Fungal Infection

A rapidly advancing ulceration of the palate covered by a black eschar, followed by loosening of the maxillary teeth and facial swelling, is the dreaded presentation of mucormycosis. This acute fungal infection, also known as zygomycosis, is caused by fungi of the order Mucorales and affects main...

A rapidly advancing ulceration of the palate covered by a black eschar, followed by loosening of the maxillary teeth and facial swelling, is the dreaded presentation of mucormycosis. This acute fungal infection, also known as zygomycosis, is caused by fungi of the order Mucorales and affects mainly immunocompromised patients. The condition is a true dental and medical emergency, and survival depends on early recognition, control of the underlying disease and aggressive surgical and antifungal therapy.

What Is Mucormycosis

Mucormycosis is a rare but rapidly progressive fungal infection caused by environmental molds of the order Mucorales, including Rhizopus, Mucor and Lichtheimia species. The fungi are ubiquitous in soil, decaying vegetation and the air, and they are inhaled or inoculated into the body. In a healthy person they cause little harm, but in an immunocompromised host the spores germinate, invade blood vessel walls and cause thrombosis, infarction and tissue necrosis, which explains the black, dying tissue that characterizes the disease.

Zygomycosis and the mycoses

The terms mucormycosis and zygomycosis are often used interchangeably. The condition belongs to a family of deep mycoses that includes aspergillosis, histoplasmosis, blastomycosis and cryptococcosis, which are caused by different fungi and have different clinical patterns.

Who is at risk

The main risk factors are diabetes mellitus, especially poorly controlled ketoacidosis, immunosuppressive therapy, organ or stem cell transplantation, neutropenia, malignancy and iron overload. In the maxillofacial region, the invasive form often follows an episode of dental infection or a recent extraction that creates a portal of entry.

Oral and Maxillofacial Manifestations

The maxillary presentation

The palate and the maxillary sinus are the most common craniofacial sites, and the infection presents as a painful, necrotic ulcer on the hard palate covered by a black or gray eschar. The teeth in the affected area become mobile, and the overlying gingiva discolors and sloughs. The facial tissues may swell, and the infection can extend into the sinus, the orbit and the brain, a sequence that is often fatal if not interrupted early.

The black eschar as a clinical sign

The hallmark of mucormycosis is the black necrotic eschar of devitalized tissue that results from vascular thrombosis. The surrounding tissue is edematous and painful, and the area does not bleed normally when probed. In a febrile immunocompromised patient, a necrotic palatal lesion should be considered mucormycosis until proved otherwise.

Orbital and neurological involvement

As the infection spreads upward, it causes orbital pain, proptosis, periorbital swelling, and cranial nerve palsies, and the patient may lose vision. Spread into the brain produces headache, altered mental status and eventually death if not treated.

Diagnosis

Clinical suspicion

The diagnosis of mucormycosis is made by the combination of the clinical picture, the risk factors, and the demonstration of the fungus in tissue or culture. A necrotic lesion in the palate or the sinus of an immunocompromised patient is an indication for immediate biopsy.

Histopathology and culture

In the histologic sections, the fungus appears as broad, non-septate hyphae that branch at right angles and invade the blood vessel walls, causing infarction of the tissue. A positive biopsy is the standard, and speed is critical because the disease can advance in hours.

Imaging

Computed tomography or magnetic resonance imaging of the midface and the brain demonstrates the extent of the sinus disease, bone destruction and intracranial spread. The imaging findings are not diagnostic by themselves, but they guide the surgical approach and the extent of debridement. The dentist should request imaging as soon as the diagnosis is considered, because waiting for symptoms to develop wastes valuable time.

Differential Diagnosis

The differential of an invasive maxillary fungal infection includes aspergillosis, which produces similar necrotizing lesions but with septate hyphae that branch at acute angles, and the other deep mycoses such as histoplasmosis, blastomycosis and cryptococcosis. Bacterial osteomyelitis of the maxilla, squamous cell carcinoma and osteoradionecrosis can also mimic the ulcerative appearance. The distinguishing factors are the risk factors, the histology and the clinical course, with mucormycosis progressing far more rapidly than any of these alternatives.

Management

Surgical debridement

The surgical debridement of all necrotic tissue is the single most important treatment, and it may remove the entire involved bone, including part of the maxilla or the sinus wall. The procedure is radical because the disease spreads through the vessels, and the margin of healthy tissue must be reached. Following the debridement, the defect may require a surgical splint, and later the patient may need a maxillofacial prosthesis or a bony reconstruction.

Antifungal therapy

The antifungal treatment of choice is amphotericin B, given intravenously in high doses as early as possible, and it is often combined with a broad-spectrum azole such as posaconazole or isavuconazole for step-down therapy. The duration of treatment is long. The drug is toxic, and monitoring is essential.

Management of the underlying disease

Equally important is the control of the predisposing condition: the glucose is corrected in a diabetic patient, the immunosuppressive drugs are reduced or stopped if possible, and the neutropenia is treated with growth factors. The patient is managed by a multidisciplinary team. Even with optimal treatment, the mortality of the rhinocerebral form remains high, reaching fifty percent in some series.

Oral Hygiene in the Recovering Patient

During and after the treatment of mucormycosis, meticulous but gentle oral hygiene is essential to protect the healing tissues and to prevent secondary infection, especially when the palate is exposed. A pressure-sensing electric toothbrush such as the BrushO cleans the remaining teeth and the soft tissues gently, with soft bristles, a two-minute timer and pressure control that avoids trauma to the fragile mucosa. The dental team should also instruct the patient in the use of bland rinses and review the hygiene routinely as the maxillary defect heals.

Conclusion

Mucormycosis of the maxilla is a rapidly fatal fungal infection of immunocompromised patients, characterized by a painful black palatal eschar, loose teeth, sinus invasion and spread to the orbit and the brain. Diagnosis requires a high index of suspicion, urgent biopsy and imaging, and it is confirmed by histology showing angioinvasive non-septate hyphae. Aggressive surgical debridement, high-dose antifungal therapy and control of the underlying disease offer the only chance of survival, and early recognition by the dental team is life-saving.

（本文由 BrushO 智能牙刷团队撰写，仅供科普参考，不构成医疗建议。）（内容由AI生成，仅供参考）

（内容由AI生成，仅供参考）