[Case report of nocardia brain abscess that needs to be distinguished from metastatic brain tumor].

We report a 62-year-old woman presenting with nocardia brain abscess that mimics metastatic brain tumor. Six months before admission to our hospital, she presented with persistent hemoptysis, and a friable endobronchial mass was detected at another hospital. However, a definite diagnosis had not been made, and then she presented with hemianopia. Her laboratory analysis results showed that she had no immunological abnormalities. T1-weighted magnetic resonance images of the brain with Gd-DTPA revealed hyperintensive multiple masses with surrounding edema. We suspected this case as metastatic brain tumor of unknown origin, and the patient underwent biopsy of the supraclavicular lymph node. Histopathology results indicated abscess, and gram staining of material obtained from the abscess showed Gram-variable rods, which were determined upon culture as acid-fast Gram-positive branching rods and identified as Nocardia asteroides. Accordingly, we diagnosed the patient as having nocardia brain abscess, and she was treated with an oral antibiotic (TMP-SMX). Four months later, the abscesses disappeared. The patient recovered after prolonged TMP-SMX therapy with no recurrence in over 9 months.