Contributed by Amer Heider, M.D. and William Pasculle, SC.D.
This is a 54-year-old white male with a history of polymyositis, type 1 diabetes mellitus, and hypothyroidism who has been on immunosuppression with methotrexate and prednisone. He presented with an episode of vomiting, headache, memory loss, cognitive decline, and right lower extremity weakness and numbness that lasted for about four hours, three days prior to admission. The symptoms were resolved spontaneously after sleep.
He reported that he had had an episode of bronchitis and sinusitis that lasted for several weeks. During that time, he had several days of fevers which resolved spontaneously. With the urging of his family he sought medical attention and an outpatient brain CT Scan at an outside hospital showed a 13mm left parasagittal rim enhancing lesion in the deep parietal lobe (Fig. 1). He was transferred to our medical center for further management.
On admission, he had some mild low-grade headaches. The patient denied any fever or chills, chest or abdominal pain, nausea or vomiting, cough or shortness of breath. Review of systems was negative for additional symptoms. He was known to have allergy to Erythromycin.
Physical exam showed temperature 36.4. Blood pressure 153/70, pulse 98, and respirations 17. Pupils were equally round and reactive to light. He had no nuchal rigidity, cervical lymphadenopathy or sinus tenderness. Lungs were clear to auscultation bilaterally. Heart exam showed regular rhythm, S1 and S2 normal with no gallop, and 2/6 Systolic ejection murmur at left sternal border with no radiation or clicks. Abdomen was soft, nontender, with no organomegaly. Extremities showed symmetrical pulses no edema, cyanosis or clubbing.
Neurological examination showed alert, oriented patient who was answering questions appropriately. Cranial nerves II through XII were intact. Motor is 5/5 in all extremities. Sensory and cerebellar functions were within normal limits. Deep tendon reflexes were symmetrical. Plantar reflexes were downgoing. No focal neurologic deficit was noted.
WBC 8.9k, 86% neutrophils, 11% lymphocytes, 3% monocytes, no eosinophils, basophils or bands. Hemoglobin 13.6, hematocrit 38.1, platelets 255k, PT/INR 10.0/1.1, PTT 26.6. Sodium 138, potassium 3.9, chloride 109, bicarbonate 20, BUN 19, creatinine 1.0, glucose 328, calcium 7.7, magnesium 2.2, phosphate 2.1. Cryptococcal antibody was not detected.
CT scan of his chest and abdomen showed mild splenomegaly with no evidence of malignancy or infection.
MRI of the brain with and without contrast showed 14mm smooth, uniform thickness contrast-enhanced, ring-like lesion in the left posterior frontal vertex parafalx region with minimal surrounding perilesional edema. The lesion showed restricted diffusion on the diffusion-weighted images (Figs. 2, 3, 4, and 5).
The diagnosis of a brain abscess was favored over a neoplastic process. The patient was started on IV Metronidazole, ceftriaxone and vancomycin. Subsequently, an image-guided biopsy had been performed showing purulent exudate and associated reactive changes, consistent with those observed in an abscess. Gram, GMS, and Fite stains show no definite microorganisms (Figs. 6 and 7).
Cultures from the abscess on sheep blood agar showed grey white bacterial colonies with B-hemolysis. Gram stain showed gram positive short bacilli and plump coccobacilli (Figs. 8, 9, 10, Fig. 11). The organism is catalase positive. Semisolid medium showed umbrella shape zone of motile organisms near the surface.