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Creutzfeldt-Jakob Disease
Safety tips for anatomic studies of possible CJD

Reprinted from the January 1996 issue of CAP TODAY

Barbara J. Crain, MD, PhD

Identifying cases at risk for Creutzfeldt-Jakob Disease (CJD)

Surgical pathology. All brain biopsies for dementia should be handled as possible CJD cases. No frozen sections should be done.

Autopsy pathology. In cases of neurodegenerative disease, examine the chart carefully for specific mention of CJD, spongiform encephalopathy, or other prion diseases. Irrespective of the clinical diagnosis, examine the chart for any of the following: rapidly progressive dementia; dementia less than three years total duration; signs or symptoms of cerebellar disease; dementia accompanied by lower motor neuron findings; demential accompanied by any focal neurologic deficit not explainable on the basis of documented structural disease (e.g., infarct, tumor); dementia with seizures, especially myoclonic seizures early in the disease course; previous dural implants; or human growth hormone treatment. If any of these warning signs is present, discuss the case with a neuropathologist or the attending neurologist.

If there is any suspicion of CJD, the autopsy should be limited to the brain only and the tissue treated as outlined below. Exceptions to this rule should be very few.

Precautions for tissue handling in the autopsy room

During the autopsy. Follow universal precautions against conventional bloodborne agents; cut-resistant gloves are preferable. Wear a mask and eye shield, although there is no evidence that CJD is transmitted by aerosols or by nonpenetrating mucosal contamination.

Confine all tissues and fluids (including running water) to the table. This may be facilitated by placing a plastic sheet over the table. Remove the calvarium with a hand saw if possible. If a Stryker saw is used, use some form of shielding (such as a plastic bag) to contain small drops of blood and tissue. Do not contaminate the outer surface of the specimen container. Clearly label the container as infectious and place in a similarly labeled secondary container. Notify the funeral home of the infectious nature of the case.

Decontaminating the autopsy room

At the conclusion of the autopsy, wash the area of the incision and any other contaminated skin surfaces with freshly opened undiluted commercial bleach (sodium hypochlorite). After 10 minutes, wash off the bleach with water. Place all gowns, gloves, plastic sheets, and other disposable supplies in "biohazard" bags and incinerate them. Alternatively, autoclave (132 degrees Celsius steam) the disposables and discard them. Disinfect any liquids on the autopsy table with an equal volume of bleach or 2 normal sodium hydroxide (2N NaOH) before disposing.

Decontaminate hard surfaces and surgical instruments with bleach or 2N NaOH. These two treatments are equally efficacious; the choice between them depends on convenience and the material being decontaminated. In general, NaOH is preferred for steel instruments because it is less corrosive than bleach. Leave the disinfectant in contact with the surface for at least 15 and preferably 60 minutes.

Decontaminating the tissue. The strongly preferred approach is formalin fixation followed by formic acid treatment of tissue blocks. Fix the intact brain in formalin for at least 10 days prior to cutting. Agitate the tissue blocks (including at least one section from each cortical lobe, basal ganglia plus cerebellum) in at least 50-100 mL of 95 percent-100 percent formic acid for one hour and then return them to formalin for two days prior to embedding. Alternatively, take the necessary diagnostic sections from the fresh brain, fix them in formalin for two to seven days (as one would a surgical biopsy for dementia), treat with formic acid for one hour, and fix again in formalin for two days. The formic acid treatment significantly reduces infectivity, although it does interfere with some silver stains for the plaques and tangles of Alzheimer’s disease.

Retain the remaining brain tissue until a diagnosis has been made. If the initial sections show CJD, proceed with a workup for Alzeheimer’s disease and other dementias.

Precautions for tissue handling in the histology lab

Tissue processing and sectioning. Tissue treated with formic acid is essentially decontaminated and may be processed routinely, although many histology laboratories still prefer hand-processing. Treat hand-processed material as potentially infectious. Wear double gloves at all times. Treat all solutions with equal volumes of fresh undiluted bleach for 60 minutes before disposal. Handle disposables, glassware, tools, etc. according to the procedures used in the autopsy room (see preceding comments). Collect all scraps of paraffin and unused sections on a disposable sheet. Use disposable microtome blades. The microtome itself may be wiped with bleach or sodium hydroxide solution, but it obviously cannot be thoroughly decontaminated. Laboratories that frequently handle possible CJD cases may wish to dedicate an old microtome to this purpose.

Handling slides and blocks. No special precautions are needed in handling intact glass slides once they have been coverslipped. Decontaminate and discard broken slides. Paraffin blocks should be stored in a properly labeled bag or box.

References

1. Brown P. Guidlines for high risk autopsy cases: special precautions for Creutzfeldt-Jakob disease. In: Hutchins G, ed. Autopsy Performance and Reporting, Northfield, Ill.: College of American Pathologists; 1990:68-74.

2. Brown P, Wolff A, Gajdusek DC. A simple and effective method for inactivating virus infectivity in formalin-fixed tissue samples from patients with Creutzfeldt-Jakob disease. Neurology. 1990;40:887-890.

Dr. Crain, of the Department of Pathology, Johns Hopkins Hospital, Baltimore, is a member of the CAP Neuropathology Committee. Her article is one of a periodic series of articles written by the members of committees composing the CAP Commission on Anatomic Pathology.