Neuropathology

Health and safety

It is essential that staff are aware of the health and safety issues.^1–16

The main danger of infection in neuropathology arises from the handling and processing of tissues from cases of AIDS, Creutzfeldt-Jakob disease (CJD), and tuberculosis.

All members of the department and mortuary staff should be immunised against hepatitis B. Because potentially dangerous cases can be encountered unexpectedly, technique should always be of a high standard and appropriate to the safety of all staff involved in the investigation. Any case of rapidly progressive dementia must be assumed to be a case of CJD until proved otherwise. The treatment of workplace, clothing, and instruments should be appropriate.

If a diagnosis of CJD is possible, samples of frozen brain, usually frontal lobe and cerebellum, should be retained for prion protein subtyping and prion protein gene sequencing. Advice is available from the CJD Surveillance Unit, Edinburgh.

Samples from cases of CJD should be handled in a class 1 cabinet in a separate level 3 containment room. Blocks for sectioning need to be processed using an appropriate inactivating agent, currently immersion in neat formic acid for at least one hour.

Cases of human immunodeficiency virus (HIV) infection can be dealt with at containment level 2 with appropriate disinfection afterwards.

Brain biopsies

Although the general principles with regard to the processing of biopsy material in neuropathology are similar to those in general histopathology, there are several important differences. Biopsy of the central nervous system is potentially dangerous for the patient. To avoid a second biopsy it is important that the surgeon knows that representative tissue has been removed. Stereotactic techniques have greatly improved the accuracy of the technique, but the amount of material removed is usually small. Fortunately, most specimens smear easily, enabling a diagnosis to be made within a few minutes.

Small specimens …