J Korean Soc Magn Reson Med.  2013 Mar;17(1):50-54. 10.13104/jksmrm.2013.17.1.50.

Nocardia Brain Abscess Mimicking a Metastatic Brain Tumor: A Severe CNS Infection Requiring Aggressive Management

• Lee A
• Kim HK

• KMID: 1426752
• DOI: http://doi.org/10.13104/jksmrm.2013.17.1.50

Abstract

Nocardiosis is an uncommon Gram-positive bacterial infection caused by aerobic actinomycetes in the genus Nocardia. Nocardia spp. have the ability to cause localized or systemic suppurative disease in humans and animals. Nocardiosis is typically regarded as an opportunistic infection, but approximately one-third of infected patients are immunocompetent. We report a rare case of pulmonary nocardiosis and a brain abscess caused by Nocardia asteroides in an elderly woman with a history of Crohn's disease. Radiographic imaging revealed a contrast-enhancing lesion with perilesional parenchymal edema that was preoperatively thought to be a neoplasm. The patient experienced aggressive disease progression simulating a metastatic brain tumor. Early diagnosis of norcadiosis, the absence of underlying disease, and the administration of appropriate antibiotics has a positive impact on prognosis. Familiarity with the magnetic resonance and computed tomography findings associated with CNS nocardiosis, such as those presented here, is essential for making an early diagnosis.

Keyword

Nocardia; Brain abscess; Surgical biopsy; CNS infection

MeSH Terms

Actinobacteria
Aged
Animals
Anti-Bacterial Agents
Brain
Brain Abscess
Brain Neoplasms
Crohn Disease
Disease Progression
Early Diagnosis
Edema
Female
Gram-Positive Bacterial Infections
Humans
Magnetic Resonance Spectroscopy
Nocardia
Nocardia asteroides
Nocardia Infections
Opportunistic Infections
Prognosis
Recognition (Psychology)
Anti-Bacterial Agents
Nocardia Infections

Figure

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  Fig. 1 Contrast-enhanced axial chest computed tomography (CT) scan showing a consolidative lesion with multiple nodules and inner necrosis in the left upper lobe (LUL) of the right lung. Fluid collection was observed in the pleural space along with left lower lobe (LLL) collapse, suggesting obstructive pneumonitis.

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  Fig. 2 An initial non-contrast-enhanced CT scan of the brain showing low attenuation of the right frontal white matter.

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  Fig. 3 Axial T2WI and sagittal T1WI MR image of the brain showing a small, ill-defined T1-low and T2-high signal intensity lesion in the right frontal white matter; a ring-enhancing lesion of approximately 8 mm was observed within the lesion following contrast infusion.

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  Fig. 4 On follow up examination after two weeks, a T2WI and contrastenhanced axial MR image of the brain showing the enlarged peripheral enhancing mass with perilesional edema in the right frontal lobe and a newly developed lesion in the right parietal lobe.

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  Fig. 5 a. Percutaneous transthoracic needle biopsy of the lung revealed a necrotizing granulomatous inflammation (Hematoxylin & Eosin stain, ×100). b. Brain specimen showing the abscess cavity (asterisk) with a surrounding rim of fibrosis (white arrow), chronic inflammatory cells, and histiocytes (black arrow) (Hematoxylin & Eosin stain, ×100). c. GMS staining of the brain abscess revealed long, branching, Gram-positive filamentous bacilli (white arrow) (×1000).

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