Specimen Collection Recommendations for Pathologic Evaluation of Central Nervous System Infections
Histopathologic changes in tissues and the pathogens that cause acute meningitis or encephalomyelitis may be distributed focally or sparsely in the central nervous system, and the predilection site for infection may vary among different organisms. For autopsies, collecting multiple representative portions of central nervous system (CNS) tissue, as well as tissue samples from any other organ system with inflammatory cell infiltrates, ensures the best chance of detecting the causative agent.
Performance of specific immunohistochemical, molecular, or other assays will be determined using clinical and epidemiologic information provided by the submitter and the histopathologic features identified in the submitted tissue specimens.
Collection of Tissue Specimens
The preferred specimens include formalin-fixed paraffin-embedded (FFPE) tissue blocks of involved CNS tissue. If an autopsy is performed, representative formalin-fixed wet tissues are also acceptable. For autopsies, representative tissue specimens from each of the following sites should be obtained and submitted for evaluation:
- Cerebral cortex (frontal, parietal, temporal, and occipital)
- Brain stem (midbrain, pons, medulla) and spinal cord
- Basal ganglia, thalamus, hypothalamus, and hippocampus
If meningitis or encephalitis is identified in the context of a systemic illness (e.g., possible meningococcemia), representative tissues should be included from any other organ showing significant microscopic pathology.