eMedicine Specialties > Infectious Diseases > Fungal Infections

Mucormycosis: Differential Diagnoses & Workup

Author: Nancy F Crum-Cianflone, MD, MPH, Consulting Staff, Department of Internal Medicine, Division of Infectious Diseases, Naval Medical Center at San Diego; HIV Research Physician, Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences
Contributor Information and Disclosures

Updated: Jul 1, 2008

Differential Diagnoses

Anthrax
Aspergillosis
Cellulitis
Colonic Obstruction
Nocardiosis
Pulmonary Embolism

Other Problems to Be Considered

Rhinocerebral
Bacterial orbital cellulitis
Cavernous sinus thrombosis
Aspergillosis
Pseudallescheria boydii infection (Pseudallescheriasis)
Rapidly growing orbital tumor

Pulmonary
Aspergillosis
P boydii infection (pseudallescheriasis)
Pulmonary embolism

Skin
Ecthyma gangrenosa associated with pseudomonal infection
Anthrax

Gastrointestinal
Bowel obstruction
Ileocecal tuberculosis

Workup

Laboratory Studies

  • The diagnosis of mucormycosis is established by obtaining a biopsy specimen of the involved tissue. Swabs of tissue or discharge are unreliable.
  • A complete blood cell count should be obtained to assess for neutropenia. A chemistry panel that includes blood glucose, bicarbonate, and electrolytes is useful to monitor homeostasis and direct correction of acidosis. An arterial blood gases study can help determine the degree of acidosis and direct corrective treatments.
  • Iron studies: Assess the presence of iron overload as shown by high ferritin levels and a low total iron-binding capacity.

Imaging Studies

  • Plain films may show sinus involvement with mucosal thickening, air-fluid levels, or bony erosions.
  • Head and facial CT scanning: This should be used as the initial investigation in rhinocerebral infections. CT scans may show sinusitis of the ethmoid and sphenoid sinuses, as well as orbital and intracranial extension. As the disease progresses, the bone may erode and the infection may spread into the brain or orbits. In addition, because these organisms have a predilection for vascular involvement, thromboses of the cavernous sinus or internal carotid artery may occur.6 All of the areas of involvement must be understood in order to plan the extent of surgical debridement.
  • MRI of the facial sinuses and brain: This is superior to a CT scan in assessing the need for ongoing surgery.
  • Chest radiography and chest CT scanning: The most common finding is consolidation, usually unilobar; with disease progression, multilobar involvement may develop. Cavitation, especially producing an air crescent, is highly suggestive of fungal infection but does not distinguish from aspergillosis. Nodular lesions and pleural effusions may be present.
  • Abdominal CT scanning: In GI disease, abdominal CT scan may show a mass associated with the GI tract.

Other Tests

  • In cases of CNS involvement, cerebrospinal fluid (CSF) findings may include elevated protein levels and a modest mononuclear pleocytosis. CSF cultures are sterile. A CT scan should precede a lumbar puncture to ensure that this procedure is safe.
  • For pulmonary disease, a bronchoalveolar lavage (BAL), biopsy, or both may assist in the diagnosis.

Procedures

The critical test procedure is obtaining a biopsy of involved tissue. Act promptly on the histological appearances of mucormycosis.

  • Biopsy of necrotic tissue (nasal, palatine, lung, cutaneous, GI, abscess wall)
    • Stains of fixed tissues with hematoxylin and eosin (H&E) or specialized fungal stains, such as Grocott methenamine-silver or periodic acid-Schiff (PAS) stains, show broad-based (10- to 20-µm diameter), ribbonlike, nonseptate hyphae with right-angle branching. Neutrophil infiltration, vessel invasion, and tissue infarction are often observed.
    • Culture of biopsy samples is required to determine the species of Mucorales. Do not crush or grind the specimen because the nonseptate hyphae are prone to damage. Growth usually occurs in 2-3 days. The genus and species are determined via examination of the fungal morphology (eg, the presence and location of the rhizoids).

Histologic Findings

Pathognomonic changes of broad, irregular, nonseptate, right-angled, branching hyphae are demonstrated by H&E and by specialized fungal stains. Vascular invasion and necrosis are the characteristic consequences of the infective process. A neutrophil infiltrate is typical, and a granulomatous reaction may be observed.

More on Mucormycosis

Overview: Mucormycosis
Differential Diagnoses & Workup: Mucormycosis
Treatment & Medication: Mucormycosis
Follow-up: Mucormycosis
Multimedia: Mucormycosis
References
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References

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Further Reading

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Keywords

Rhizopus species, mucormycosis, zygomycosis, phycomycosis, Mucorales, Rhizopus mucormycosis , Rhizomucor mucormycosis , Cunninghamella mucormycosis , Apophysomyces mucormycosis , Saksenaea mucormycosis , Absidia mucormycosis , Mucor mucormycosis , Syncephalastrum mucormycosis , Cokeromyces mucormycosis , Mortierella mucormycosis, conidiobolomycosis, entomophthoramycosis, basidiobolomycosis, pulmonary mucormycosis, rhinocerebral mucormycosis, cutaneous mucormycosis, gastrointestinal mucormycosis, disseminated mucormycosis

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Contributor Information and Disclosures

Author

Nancy F Crum-Cianflone, MD, MPH, Consulting Staff, Department of Internal Medicine, Division of Infectious Diseases, Naval Medical Center at San Diego; HIV Research Physician, Infectious Disease Clinical Research Program, Uniformed Services University of the Health Sciences
Nancy F Crum-Cianflone, MD, MPH is a member of the following medical societies: American College of Physicians and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Medical Editor

Maria D Mileno, MD, Assistant Professor, Department of Internal Medicine, Division of Infectious Diseases, Brown University
Maria D Mileno, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, International Society of Travel Medicine, and Sigma Xi
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Ronald A Greenfield, MD, Professor, Department of Internal Medicine, Section of Infectious Diseases, University of Oklahoma College of Medicine
Ronald A Greenfield, MD is a member of the following medical societies: American College of Physicians, American Federation for Medical Research, American Society for Microbiology, Central Society for Clinical Research, Infectious Diseases Society of America, Medical Mycology Society of the Americas, Phi Beta Kappa, Southern Society for Clinical Investigation, and Southwestern Association of Clinical Microbiology
Disclosure: Pfizer Honoraria Speaking and teaching; Gilead Honoraria Speaking and teaching; Ortho McNeil Honoraria Speaking and teaching; Wyeth Honoraria Speaking and teaching; Abbott Honoraria Speaking and teaching; Astellas Honoraria Speaking and teaching; Cubicin  Speaking and teaching

CME Editor

Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital
Eleftherios Mylonakis, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Physicians, American Society for Microbiology, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

Chief Editor

Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Burke A Cunha, MD is a member of the following medical societies: American College of Chest Physicians, American College of Physicians, and Infectious Diseases Society of America
Disclosure: Nothing to disclose.

 
 
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