Mucormycosis classification

Mucormycosis Microchapters
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Syed Hassan A. Kazmi BSc, MD [2]

Overview

Mucormycosis may involve various organ systems including brain, lungs, skin, GIT, bones, liver, spleen and can be classified based on the organ system involvement. Disseminated infection is associated with high mortality.

Classification

Mucormycosis may be classified based on the organ system involvement:

Rhinocerebral mucormycosis

• Rhinocerebral mucormycosis is by far the most common form of the disease. It occurs most commonly in debilitated patients (specially those presenting with diabetic ketoacidosis).
• Another patient population that has been found to be susceptible to mucormycosis are those undergoing hematopoietic stem cell transplantation.
• Initial symptoms include eye or facial pain and facial numbness, followed by the onset of conjunctival injection, blurry vision, and soft tissue swelling.
• If untreated, infection usually spreads from the ethmoid sinus to the orbit, resulting in loss of extraocular muscle function and proptosis.
• The infection may rapidly spread into the neighboring tissues.
• Onset of signs and symptoms in the contralateral eye, with resulting bilateral proptosis, chemosis, vision loss, and ophthalmoplegia, is a sign that suggests the development of cavernous sinus thrombosis.
• Infection can also spread posteriorly from either the orbit or sinuses to the central nervous system.
• A bloody nasal discharge may be the first sign that infection has invaded through the turbinates and into the brain.
• Hematogenous spread may lead to development of mycotic aneurysms.

Pulmonary mucormycosis

• Pumlonary mucormycosis most commonly occurs in neutropenic and stem cell transplant patients.
• It develops as a result of inhalation or by hematogenous or lymphatic spread.
• Symptoms include dyspnea, cough, chest pain and hemoptysis (if there is vessel involvement through vascular invasion)
• Disseminated disease leads to a poorer prognosis.

Cutaneous mucormycosis

• Disruption of the physiologic skin barrier may lead to invasion of the fungi causing mucormycosis and development of disease.
• Agents responsible for mucormycosis are not capable of penetrating the skin, however, trauma, skin maceration or burns may lead to disruption of the normal barrier.
• Contaminated surgical dressings may also lead to development of mucormycosis.
• Disseminated disease may result if infection from the skin penetrates into subcutaneous tissues, fat and bones.

Gastrointestinal mucormycosis

• Gastrointestinal mucormycosis is a rare occurrence and is usually found in malnourished individuals, AIDS patients, SLE patients, organ transplant recepients, infants and children.
• Ingestion of the fungi is the most common route of transmission.
• Symptoms include abdominal distension, pain, nausea, vomiting and hematochezia.
• Biopsy via endoscopy is required to confirm the diagnosis.

Disseminated mucormycosis

• Hematogenous spread is usually the most common route of dissemination and pulmonary mucormycosis is usually the culprit.
• Brain is the most common site of dissemination but other organs may also be involved, including spleen, heart , liver and skin.
• Cerebral dissemination may result is abscess formation.
• Disseminated infection is associated with a high case fatality rate (may approach 100 %)
• Patients on immunosupressants and anti-fungal prophylaxis (escpecially voriconazole) are particularly susceptible to disseminated infection.
• Infarctions in multiple organs in an immunosuppressed patient points towards disseminated mucormycosis.