Case Study 1Harry Kellermier, M.D.

Question 1This is a 70 year-old male who presented with paresthesias and clumsiness in his right upper extremity.  What are the abnormal findings seen in these radiographs?

AnswerMass lesion

In the left frontoparietal regionIrregular Peripherally enhancing

Surrounding edema

Question 2What is your differential from these radiographs?

AnswerMalignant glioma; Metastasis; Lymphoma; Abscess; Subacute infarct.

Question 3EXAMINE SMEAR.  An intraoperative consultation was requested.  Describe the microscopic findings on this slide.

Click here to view slide

AnswerReactive astrocytes with abundant eosinophilic

cytoplasmBackground acute and chronic inflammatory

cellsMacrophagesVessels with plump, reactive endothelium

Question 4What would the intraoperative consultation be based on the previous smear? (A: Category such as Defer, Reactive, or Neoplastic; B: More specific diagnosis)

AnswerDeferReactive and inflammatory changes

Question 5EXAMINE H&E. The permanent section from the intraoperative specimen has returned from histology.  Describe the microscopic findings on this slide.

Click here to view slide.

AnswerFibrovascular tissueNecrotic tissueInflammatory infiltrate consisting of acute and

chronic inflammatory cellsMacrophages

Question 6What additional studies would you like based on this permanent specimen.

AnswerGMSGram stainCheck microbiology results

Question 7EXAMINE GRAM STAIN: What do you see on this slide?

Click here to view slide.

AnswerSlender, branching gram positive rods

Question 8EXAMINE GROCOTT STAIN.  What do you see on this slide?

Click here to view slide.

AnswerFilamentous, branching rods

Question 9What organisms are in your differential?

AnswerNocardiaActinomycesStreptomyces

Question 10What additional stain would you order (pictured below)?A.Ziehl-NielsenB.FiteC.Luxol Fast BlueD.Warthin-StarryE.Modified Gram Stain

AnswerThe answer is B. Fite.

Question 11By what route of infection did this patient acquire Nocardia?

AnswerNocardia species are widely distributed in the environment.  The usual route of infection is by inhalation and pulmonary involvement, with subsequent spread to other sites.  Nocardia asteroides complex accounts for approximately 80% of cases of noncutaneous invasive disease.  According to some reports, the CNS is the second most commonly affected organ with some studies citing secondary CNS involvement in approximately 25% of cases.  Despite this apparent affinity for the CNS, Nocardia accounts for only approximately 2% of all brain abscesses.  Patients who develop nocardial brain abscesses are typically immunosuppressed.  Commonly affected groups include organ transplant recipients, persons with connective tissue diseases, HIV, pulmonary diseases and underlying malignancies.  Less commonly, Nocardia may present as a meningitis, diffuse cerebral infiltration, or granulomas.

Epidemiology0.3-1.3 per 100,000 people per year

Higher in immunocompromised patientsCausative organisms

Streptococcus species- 34%Viridans 13%, pneumoniae 2%

Staphylococcus species- 18%Aureus 13%, epidermidis 3%

Gram negative enteric- 15%Proteus 7%Klebsiella, E.Coli, enterobacteriae all 2%

Nocardia- 1%

Distribution of causative microorganisms through

time

Predisposing conditionsOtitis/mastoiditis- 32%Sinusitis- 10%Hematogenous- 13%Meningitis- 6%Postoperative- 9%Unknown- 19%

Location81% of the time only a single lesion was

identifiedFrontal lobe- 31%Temporal lobe- 27%Parietal lobe- 20%Cerebellar and brainstem- 13%

Diagnosis and outcomeAspiration with culture and smear!MRI>CT scan

DWI hyperintense signal with correlating hypointense signal on ADC had a 96% sensitivity and specificity for differentiating abscess from other intracranial cystic mass

Outcome20% Mortality57% Good outcome

References Brouwer et al. ‘Clinical characteristics and

outcome of brain abscess: Systemic review and meta-analysis.’ Neurology, 1/29/2014