Put a Ring to it: Disseminated Nocardia Beijingensis Mimicking Metastatic Disease
Bobbi Thursam1, Aileen Antonio1, Muhammad Farooq1, Bryan Figueroa1
1Hauenstein Neurosciences, Trinity Health Grand Rapids
Objective:
To present a rare case of central nervous system ring-enhancing lesions in an immunocompromised patient, ultimately diagnosed with disseminated Nocardia beijingensis.
Background:
Nocardia beijingensis is an uncommon, opportunistic, gram-positive pathogen. Due to its rarity, central nervous system (CNS) lesions caused by Nocardia beijingensis may be misinterpreted as metastases, potentially delaying appropriate antimicrobial therapy.
Results:
A 67-year-old male with a history of deceased-donor kidney transplantation (on mycophenolic acid and tacrolimus) and prostate cancer presented with encephalopathy and a generalized tonic-clonic seizure. Brain MRI revealed 5 ring-enhancing lesions in the bilateral cerebral hemispheres, initially concerning abscesses or metastases. CT imaging of the chest, abdomen, and pelvis showed enlarged lymph nodes, biliary and liver cysts, biliary duct dilation, pleural effusion, and right adrenal nodule – findings that raised suspicion for metastatic disease.
Cerebrospinal fluid analysis following lumbar puncture was largely unremarkable, except for mildly elevated protein (101 mg/dL). Based on the overall clinical picture, the working diagnosis favored metastases, and empiric antibiotics were discontinued.
However, further review of the brain MRI revealed features more consistent with abscesses: thin and regular wall enhancement, presence of the double-rim sign, extensive surrounding edema relative to lesion size, and central diffusion restriction with corresponding low ADC. Stereotactic brain biopsy confirmed the diagnosis of Nocardia beijingensis. The organism was resistant to imipenem, and the patient was subsequently treated with ceftriaxone and moxifloxacin, with clinical improvement.
Conclusions:
Ring-enhancing lesions on neuroimaging often raise concern for abscesses, metastases, or demyelinating processes. Careful evaluation of imaging characteristics is essential, as these can provide critical clues that guide accurate diagnosis and timely intervention. Nocardia beijingensis, though rare, can present with pulmonary, cutaneous, or disseminated disease, including central nervous system involvement. Misidentifying nocardial abscesses as metastatic lesions may lead to delays in initiating appropriate, potentially lifesaving antimicrobial therapy.
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