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Discussion Starter · #1 ·
A 38-year-old Caucasian male undergoing treatment for acute myelogenous leukemia (AML) complains of severe right-sided headaches. Physical examination reveals right-sided proptosis and periorbital tenderness. Biopsy of the right maxillary sinus mucosa reveals the following:


Which of the following is the most likely cause of this patient's condition?

A. Malassezia furfur
B. Microsporum can/s
C. Rhizopus species
D. Aspergillus fumigatus
E. Candida albicans
F. Cryptococcus neoformans
G. Blastomyces dermatitidis
H. Histoplasma capsulatum
I. Coccidioides immitis
J. Sporothrix schenckii
 

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Discussion Starter · #4 ·
C) Rhizopus species

Mucor, Rhizopus and Absidia species are saprophytic fungi present in the environment. They are transmitted by spore inhalation and cause mucormycosis. Patients with underlying immunosuppression (e.g. solid organ transplantation patients, patients with hematologic malignancies, patients undergoing corticosteroid treatment) are at high risk. Mucormycosis is also very strongly associated with diabetic ketoacidosis.

Mucormycosis tends to affect the paranasal sinuses. Patients complain of facial and periorbital pain, headache and purulent nasal discharge. The fungi proliferate in the walls of blood vessels and cause necrosis of the corresponding tissue. Black eschar (necrotic tissue) may be seen on the palate or nasal turbinates.

Mucormycosis is diagnosed by light microscopy of a tissue specimen. Mucor, Rhizopus and Absidia fungi exist in mold form only. They form broad nonseptate hyphae that branch at wide (often 90° angles). The typical histologic appearance is shown on the slide above. Mucormycosis is treated by surgical debridement of necrotic tissue and amphotericin B.
 
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