Actinomycotic Brain Abscess Developed 10 Years after Head Trauma
A healthy 45-year-old man presented with 3 days of left-sided weakness, left-sided facial palsy, and dysarthria. His medical history was remarkable for a laceration head injury 10 years prior. He received a surgical suture and was admitted to the intensive care unit because mild intracranial hemorrhage was identified. He recovered with conservative management and the injury did not leave any neurologic sequelae. The patient and his family denied having any history of heavy alcohol consumption, dental carries, cancer, diabetes mellitus, or surgery on orofacial, thoracic, or abdominal areas. Physical examination revealed that the patient was drowsy but well oriented and afebrile. Laboratory examinations showed a white blood cell count of 9,900/mm3 with a differential count of 68% segmented cells and 23% lymphocytes. The erythrocyte sedimentation rate was 18 mm/hr and the C-reactive protein was 0.3 mg/dL. The initial non-enhanced brain computed tomography demonstrated a 3.5×2.5 cm irregular mass in the right frontal lobe with severe perilesional edema. Brain magnetic resonance imaging showed that the lesion was hypointense on a T1-weighted image and hyperintense on a T2-weighted image, with thick and irregular ring-like enhancement. A diffusion weighted image demonstrated high signal intensity, reflecting restricted diffusion (). For a definite diagnosis and treatment, the patient underwent open surgery and the mass was excised along with surrounding brain parenchyma. Grossly, the specimen included an abscess cavity containing yellowish green pus, surrounded by a thick fibrous capsule. Histological examination showed multiple filamentous organisms appearing as radiating rosettes in the central areas of the abscess (). These structures stained positively with periodic acid-Schiff, Grocott's methenamine silver, Gram stain, and negative with acid-fast stain (). These findings were consistent with the sulfur granules of actinomycoses. After the operation, the patient recovered consciousness and 4 weeks of intravenous ampicillin therapy was started (12 g/day). Streptococcus viridans was isolated from the infected brain during antibiotic treatment. However, Actinomyces species were not isolated, despite prolonged culture. The patient was discharged with a good outcome after 4 weeks and continued with 4 months of oral administration of ampicillin.