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
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
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
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)
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
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.
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.
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.