Skull base thrombotic mycosis.

A 69-year-old man with multiple medical comorbidities experienced a left hemispheric cerebrovascular accident following an extensive clinical evaluation for a left skull base process. He had been receiving anticoagulation therapy subsequent to recent coronary artery bypass grafting, and he developed a concurrent right occipital subdural hematoma with subsequent clinical deterioration. Soon thereafter, he died as a result of neurologic sequelae.

During a previous evaluation, computed tomography (CT) of the internal auditory canals and contrast-enhanced CT of the neck had detected a soft-tissue abnormality in the region of the left nasopharynx and the left carotid canal. Positron-emission tomography showed uptake in the left skull base, which raised the possibility of a malignancy. However, an upper-level neck and skull base dissection and nasopharyngeal biopsy ruled out a lymphoma or other malignancy, and a Gram's stain and culture of the surrounding lymph nodes were negative for pathogenic bacteria. Fungal preparations were negative. While fungal cultures were pending, the patient was started on long-term intravenous antibiotic therapy for presumed skull base osteomyelitis, which had been suggested by a positive finding on indium 111 white blood cell nuclear imaging.

Following the patient's death, autopsy revealed a total occlusion of the left internal carotid artery and an invasion of the vessel wall by nonseptate fungal organisms (figure, A and B). Candida parapsilosis ultimately was isolated on fungal cultures.

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This particular fungus is associated with opportunistic infection, typically in immunocompromised hosts. C parapsilosis has a particular affinity for indwelling access devices and prosthetic heart valves, and it is frequently found in intensive care units. However, most cases of fungal skull base osteomyelitis in the literature have been associated with Aspergillus niger. This case illustrates the need to consider fungal skull base infection in the differential diagnosis for any patient with a skull base lesion, particularly an immunocompromised patient.

Suggested reading

Hanna E, Hughes G, Eliachar I, et al. Fungal osteomyelitis of the temporal bone: A review of reported cases. Ear Nose Throat J 1993;72:532, 537-41.

Kerr J. Fungal osteomyelitis of the temporal bone: A review of reported cases. Ear Nose Throat J 1994;73:339.

Kountakis SE, Kemper JV Jr., Chang CY, et al. Osteomyelitis of the base of the skull secondary to Aspergillus. Am J Otolaryngol 1997;18:19-22.

Kuhn DM, Mikherjee PK, Clark TA, et al. Candida parapsilosis characterization in an outbreak setting. Emerg Infect Dis 2004;10: 1074-81.

Shelton JC, Antonelli PJ, Hackett R. Skull base fungal osteomyelitis in an immunocompetent host. Otolaryngol Head Neck Surg 2002;126:76-8.

Eric P. Wilkinson, MD; Robert A. Robinson, MD, PhD; Douglas K. Trask, MD, PhD

From the Department of Otolaryngology (Dr. Wilkinson and Dr. Trask) and the Department of Pathology (Dr. Robinson), University of Iowa Hospitals and Clinics, Iowa City.