Mucormycosis can invade different body systems. Sites of infection include the lung, central nervous system, paranasal sinuses, gastrointestinal system, and the skin. Its clinical manifestations are varied but characteristically demonstrate rapid progression. The clinical manifestations largely depend on the route of entry of the fungus and the predisposing disease.

Rhinocerebral mucormycosis is initiated with inhalation of spores into the paranasal sinuses and the invasion of blood vessels in the tissue. The infection starts with nasal congestion or discharge, though it may progress to facial numbness, blurry vision, nasal discharge, nasofrontal headache, ocular pain, fever, diplopia, and chemosis. Intranasal lesions characteristically have painless ulcerations with exudate and necrotic tissue, and usually progress rapidly over days. In an immunocompromised patient with prolonged nasal symptoms, one should maintain a low threshold to obtain a biopsy to rule out mucormycosis (often termed "invasive fungal sinusitis - IFS).

Pulmonary mucormycosis consists of the development of bilateral pneumonia, which is rapidly progressive and the result of the inhalation of infectious material.  The most common clinical features are fever, hemoptysis, dyspnea, and cough. This clinical form is seen more frequently in patients with hematological diseases. This pulmonary condition can present as bronchitis, bronchopneumonia, and even pulmonary embolism. The infection can spread to contiguous tissues, such the mediastinum and heart, though it may also lead to cavitary lesions that can mimic tuberculosis or more benign allergic fungal disease. 

Cutaneous mucormycosis presents in both primary and secondary disease. In primary disease, the skin infection results from direct inoculation and in secondary form, by dissemination from other locations. The primary form often occurs in patients with burns and traumatic skin wounds, usually appears as a single and indurated area of cellulitis that progresses a necrotic lesion, other forms of manifesting are abscesses, skin swelling, and necrosis.

Gastrointestinal form occurs via the ingestion of contaminated food, though the use of contaminated herbal medicines has been linked to gastrointestinal disease development. There may be nausea, vomiting, ulceration, and thrombosis of the gastric, esophageal and intestinal mucosa, manifested by diarrhea, hematemesis, and melena. Perforation and peritonitis can result from necrotic ulcers. Also, the presence of bowel infarctions and hemorrhagic shock lead to poor prognosis. Gastrointestinal symptoms are rare in all but the most severely immunocompromised (leukemia patients, intestinal transplant patients, etc.), owing to a large amount of immune tissue in the GI tract.

Disseminated form of mucormycosis may originate from any primary sites of infection, manifestations are nonspecific, which makes diagnosis even harder, but a metastatic skin lesion is undoubtedly a sign to suspect disseminated mucormycosis and portends a dismal prognosis.[4][5][7][8][9]

Routine blood work is rarely diagnostic but can find the presence of neutropenia as a correlating risk factor.   

Imaging can be valuable in evaluating the extent of the disease. Radiological imaging studies are required to investigate areas with suspected mucormycosis, specifically in the brain, paranasal sinuses, lungs, and abdomen, always guided by the clinic.

The first intervention in the suspicion of rhinocerebral mucormycosis is with the endoscopic evaluation and biopsy of the sinuses to examine for tissue necrosis and to obtain examples of tissue, the presence of characteristic hyphae provides a presumptive diagnosis. The area of highest-yield, and greatest accuracy, is to biopsy the middle turbinate. A computed tomography (CT) scan can help evaluate contiguous structures such as the eyes and brain, findings in CT scan included soft tissue edema of cavity mucosa, sinus mucoperiosteal thickening, bone erosions, and orbital invasions.

Patients with immunosuppression and respiratory symptoms should have a CT chest for possible pulmonary mucormycosis. The presentation of the infection does not differ from pneumonia; therefore, the diagnosis is difficult. Chest radiologic findings are pleural effusion, nodules, consolidation, and ground-glass infiltrates. Bronchoalveolar lavage can show broad nonseptate hyphae.

If there is a concern for gastrointestinal mucormycosis (abdominal pain, gastrointestinal bleeding), a CT scan to evaluate for colitis is necessary.  Once confirmed, colitis should be further investigated by endoscopy with biopsy.  The presence of characteristic hyphae in the biopsy provides a presumptive diagnosis.[7][10]

The standard management of mucormycosis requires early diagnosis, a reversal of risk factors and underlying illness, surgical debridement, and prompt administration of intravenous antifungals - usually amphotericin B.  This entails the prompt management of hyperglycemia, acidosis, and cessation of immunosuppressive agents when possible.

Amphotericin B is considered first-line therapy for mucormycosis. The lipid formulation of amphotericin B is administered in high doses intravenously once a day as initial therapy. The initial starting dose is 5 mg/kg IV daily, with a maximum dose of 10 mg/kg IV. Treatment duration depends upon the patient's clinical picture. 

Surgical debridement of infected tissue should be urgently performed to limit the further spread of infection. Aggressive surgical debridement of necrotic tissue should take place immediately. This may involve radical facial resections, partial pneumonectomy, colectomy, etc., in accordance with the site of disease. Similar to necrotizing fasciitis, this requires very aggressive surgical management and often carried dramatic morbidity. Unless the immune status can be restored, the outcomes are unfortunately very poor even with the most aggressive therapies and drastic surgical intervention.

Posaconazole or isavuconazole has some evidence as second-line therapy in mucormycosis. For salvage treatment, posaconazole 200 mg IV four times daily is recommended. The guidelines do not support the combination of amphotericin and posaconazole. 

Other adjuncts include hyperbaric oxygen. The increased oxygen pressure improves the ability of neutrophils to kill the organism and facilitates wound healing.[10][6]

In a case of mucormycosis in its rhinocerebral form, one must consider different pathologies such as orbital cellulitis and cavernous sinus thrombosis.

When we consider the diagnosis of pulmonary mucormycosis, we should think about aspergillosis, nocardiosis, and Wegener's granulomatosis.[11]

The prognosis is dependent upon the timing of therapeutic intervention, as well as the degree of the underlying immunodeficiency of the patient with mortality ranging from 25% to 87% depending on the site of infection.

Severity and poor prognostic indicators include disseminated infection, renal injury, central nervous system disease, and inadequate response to medical treatment. The most important prognostic factor is the ability to restore a normal immune status. If this is not possible, the prognosis is uniformly dismal. If immunocompetence can be restored, even temporarily, then prognosis does improve.[11]

Complications of mucormycosis subdivide into those that result from the disease itself and those that are caused by the antifungal treatment. Complications associated with the disease are cavernous sinus thrombosis, disseminated infection, periorbital destruction, palatine ulcers, osteomyelitis, and death.

Complications due to treatment are nephrotoxicity, hypokalemia, prolonged hospitalization (specifically with the use of deoxycholate amphotericin B).

The key to the diagnosis is the identification of key risk factors and hallmark symptoms. The "classic" presentation is the immunocompromised patient, with rhinosinusal involvement, demonstrating a very rapid progression of infection, and the presence of tissue necrosis. If there is any suspicion, early endoscopic biopsy is warranted to avoid disaster potentially.

Depending on the degree of immunosuppression and predisposing conditions, the progression of the disease can be acute, fulminant, or chronic.

The identification of the exact species that cause mucormycosis is not straightforward due to the difficulty of isolating the fungus in culture media. However, regardless of the causative species and clinical presentation, therapeutic management is the same.

Mucormycosis is a life-threatening fungal infection, with very high mortality. Interprofessional management typically consists of infectious disease, otolaryngology, hematology/oncology, endocrinology, microbiology, specialty-trained nursing, and pharmacist assistance of therapeutic drug administration and monitoring, all collaborating across disciplines to achieve optimal patient results. Coordination of care among nurses and clinicians will lead to the best outcomes. [Level 5] However, even with prompt, adequate evaluation and treatment by the interprofessional team, the prognosis remains poor.