Ring-enhanced mass in the brain of a woman with systemic lupus erythematosus and elevated serum CA19-9 level: brain abscess or metastatic tumor?--case report.

A 70-year-old woman with systemic lupus erythematosus presented with a brain abscess manifesting as progressive monoparesis of the right lower extremity over 4 days. She had had no episodes of fever, and did not complain of headache or exhibit any signs of meningeal irritability. Computed tomography of the brain showed a round, low-density mass with strong ring enhancement in the left frontal lobe. Laboratory examination found a moderately elevated serum level of CA19-9, a marker of some digestive organ cancers. Together with the absence of febrile episodes, headache, and a rise in leukocyte count, the initial suspicion was metastatic brain tumor rather than brain abscess. However, diffusion-weighted magnetic resonance imaging depicted the mass as a very hyperintense area. The neuroimaging diagnosis was brain abscess. After conservative treatment with intravenous antibiotics for 6 weeks, the brain abscess completely resolved, and the patient was discharged without neurological deficits.