Mucormycosis

• Patho/Etiology

  • Caused by fungi of the order Mucorales (e.g., Rhizopus, Mucor).
  • Spores are inhaled and germinate in the upper airways or are inoculated through skin trauma.
  • Angioinvasion is the hallmark: hyphae invade blood vessels, causing thrombosis, ischemia, and extensive tissue necrosis.
  • Fungi thrive in high glucose and acidic environments.

• Key Associations (Risk Factors)

  • Diabetic ketoacidosis (DKA) is the most classic association.
  • Immunocompromised states: hematologic malignancies (leukemia, lymphoma), neutropenia, organ/stem cell transplant.
  • Long-term corticosteroid use.
  • Iron overload (e.g., hemochromatosis) and treatment with deferoxamine.
  • Severe trauma or burns.

• Clinical Presentation

  • Presentation depends on the site of infection. Forms include rhinocerebral, pulmonary, cutaneous, GI, and disseminated.
  • Rhinocerebral (most common): Starts like acute sinusitis with facial pain, headache, and nasal congestion. Progresses rapidly to cause:
    • Black necrotic eschar on the nasal turbinates or hard palate.
    • Periorbital swelling, proptosis, diplopia, and vision loss due to orbital invasion.
    • Cranial nerve palsies.
    • Altered mental status if it extends into the brain via the cribriform plate.
  • Pulmonary: Fever, cough, dyspnea, hemoptysis; often seen in neutropenic patients.
  • Cutaneous: Erythematous lesion progressing to a necrotic ulcer with a central black eschar, often at a site of trauma.

• Diagnosis

  • Urgent tissue biopsy is the gold standard for diagnosis.
  • Histopathology: Shows broad, nonseptate (or pauciseptate) hyphae with wide-angle (90° or right-angle) branching.
  • Imaging (CT/MRI): Used to assess the extent of sinus, orbital, and intracranial involvement. Findings include mucosal thickening and bony erosion.
  • Culture is often negative and should not delay treatment.

• DDx (Differential Diagnosis)

  • Rhinocerebral: Invasive aspergillosis (has septate hyphae with acute-angle branching), bacterial sinusitis (less rapid, no eschar), cavernous sinus thrombosis.
  • Pulmonary: Invasive aspergillosis, lung abscess, malignancy.
  • Cutaneous: Ecthyma gangrenosum (caused by Pseudomonas aeruginosa), necrotizing fasciitis.

• Management/Treatment

  • A true medical and surgical emergency.
  • 1. Surgical Debridement: Aggressive and immediate removal of all necrotic tissue is crucial.
  • 2. Antifungal Therapy:
    • First-line: Liposomal Amphotericin B (IV).
    • Alternatives/Step-down: Posaconazole or Isavuconazole.
  • 3. Reverse Underlying Condition: Control hyperglycemia and acidosis in DKA, reduce immunosuppressants if possible.

• Complications

  • Cavernous sinus thrombosis, carotid artery thrombosis.
  • Brain abscess, massive tissue destruction, blindness.
  • Disseminated disease and death. The overall mortality rate is very high (~50%).