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MELANOMA
LYMPHOSCINTIGRAPHY
Because
melanoma is known to spread quickly from the skin to other
parts of the body, it is of utmost importance to use every
method possible to determine if that process has begun. One
highly successful method of determining spread is by lymphoscintigraphy.
This procedure uses a radioactive tracer injected into the
body’s lymph system to locate the sentinel lymph node
or nodes. The sentinel lymph node is the first lymph node
that filters the lymph fluid coming from a certain area of
skin or body part and thus is the node most likely to be affected
by cancer spread. In the case of melanoma of the skin, sentinel
lymph node biopsy is performed to determine whether the melanoma
has spread.
Procedure
Description
The patient comes to the nuclear medicine department at Raleigh
Radiology–Rex Hospital. A radioactive tracer is injected
intradermally around the melanoma site. Usually 4 to 6 injections
are made, and during the injections the patient will feel
a burning sensation. A gamma camera will be placed over the
injection site, and sequential images will be obtained until
the sentinel node or nodes are visualized. Once the sentinel
node is identified, a small temporary tattoo mark will be
made directly over the area by placing a dot of ink under
the skin with a sterile needle. The tattoo will aid the surgeon
during surgery.
On
the day of surgery the patient will return to the nuclear
medicine department 2 hours before the scheduled surgery time,
and radioactive tracer will again be injected intradermally
around the melanoma site. No images will be taken at this
time.
Two
hours after injection of the radioactive tracer, the patient
will arrive in surgery. After anesthesia is administered,
the surgeon will inject 2 to 5 cc 1% isosulfan blue dye around
the melanoma site. A hand-held gamma probe called a Neoprobe
will be used to identify “hot” or radioactive sentinel
lymph nodes. These nodes may also be stained blue as well
from the blue dye. Lymph nodes with high radiation counts
and/or stained blue are considered sentinel nodes and will
be removed and studied intensively by the pathology department.
If no cancer cells are found in the sentinel nodes, no further
lymph nodes will be removed.
Patient
Preparation for the Procedure
No special preparation is needed before the procedure. On
the actual day of surgery, follow suggested preparations for
surgery given by your physician.
Frequently
Asked Questions about Melanoma Lymphoscintigraphy
Q:
How long does the procedure take?
Usually the first procedure that includes the temporary tattooing
takes from 1 to 2 hours. The time for the second procedure
is of course included as part of the surgery.
Q:
Does this procedure have side effects?
There will be slight pain and redness at the injection site
following injection of the radioactive tracer. The blue dye
may leave a discolored area in the skin where injected, in
the lymphatic channels, and in the urine. Skin may remain
discolored for several weeks, though urine will return to
normal in 2 to 3 days. Rarely, some people are allergic to
the blue dye.
Q:
How much radiation will I be exposed to in undergoing the
lymphoscintigraphy?
The lymphoscintigraphy exposes you to less radiation than
a normal chest X-ray.
Q:
What are the benefits of this procedure?
Benefits include a smaller incision to remove lymph nodes,
shorter recovery time, and also a careful microscopic scrutiny
by pathology of the sentinel lymph nodes with possibly more
accurate prediction of whether the cancer has spread.
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