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Neuroradiology Case of the Week

Case 387

February 2009

Charles Hubeny, MD

Clinical Presentation: An 11-year-old boy with a past medical history significant for chronic granulomatous disease and Crohn’s disease on steroids and azathioprine therapy presented with abdominal pain and found to have pneumonia. Later in his hospital course he developed visual changes and poor coordination. Bronchoalveolar lavage (BAL), blood, and urine cultures were negative but fungal stains and culture from a brain biopsy of a dominant lesion showed zygomycete.

Imaging Findings: CT and MR findings consistent with multifocal cerebritis and fungal lung infection.

Diagnosis: Fungal septic emboli with lungs as the most likely source

Discussion: Fungal illnesses can occur in immunocompetent patients but more frequently infect those immunocompromised such as from AIDS, chemotherapy or steroid treatment, or transplant recipients. Common pathologies include histoplasmosis, cryptococcus, candida, blastomycosis, and coccidomycosis. Histoplasmosis is usually acquired by inhalation from chicken, pigeon, and bat feces in the Ohio and Mississippi river valleys. Affecting those with weak immune systems, cryptococcus can cause granulomatous meningitis or brain parenchymal disease. Candida occurs worldwide and is common in diabetics and the immunocompromised. Endemic in Mississippi, Arkansas, Kentucky, Tennessee, Wisconsin and Africa blastomycosis rarely cases infects the CNS but can cause skin and lung infections. Coccidomycosis common in the southwest US and South America usually infects the immunocompromised. CSF studies with CNS fungal infections usually show low glucose, high protein, and cellular pleocytosis. Meningitis, granuloma/abscess formation, and encephalitis are usual ways in which these infections can present in the brain. Rarely, fungal septic emboli from other sources result in infection or stroke.
     Endocarditis and sepsis, or IV drug use, infected catheters, pulmonary infection, pulmonary AV fistulas, and septic thrombophlebitis with a septal defect may also cause septic emboli to the brain. Septic emboli are usually bacterial (Staph. aureus) but can rarely be fungal. Edema and enhancement are common findings with septic emboli. If the emboli are associated with persistent mass effect, edema, and enhancement beyond six weeks then septic infarction should be considered. Cerebritis, abscess, mycotic aneurysm, or obliterative vasculitis may occur as sequela. Mycotic aneurysm is a complication that can present with intracranial or subarachnoid hemorrhage usually in middle cerebral artery territory.

References:

1. Grossman RI, Yousem DM. Neuroradiology: The Requisites. Philadelphia, PA: Mosby, 2003.
2. Weissleder R, Wittenberg J, Harisinghani MG, et al. Primer of Diagnostic Imaging. Philadelphia, PA:Mosby, 2007.