A 55 year old man with a scalp lesion was
diagnosed with malignant melanoma. A lymphoscintigraphy for
identifying the sentinel lymph nodes for excisional biopsy was
performed. The Sentinel lymph node is the first lymph node in a
lymph node bed to receive the lymphatic drainage from a tumor.
The previous scalp biopsy revealed the
SKIN, SCALP, BIOPSY: MALIGNANT MELANOMA
BRESLOW DEPTH: 1.8 mm
CLARK LEVEL: IV
HOST RESPONSE: BRISK
VASCULAR SPACE INVASION: NEGATIVE
PERINEURAL INVASION: NEGATIVE
SURGICAL MARGINS: EXCISED
Staging of these tumors is based on
tumor thickness (Breslow measurement) and level of skin invasion
(Clark's level), both of which are determined by the pathologist from
the biopsy sample. Ample data correlate patient survival with
Breslow and Clark measurements. Sentinel node biopsy is
frequently performed in patients without either clinically apparent
metastases or early intermediate-stage melanoma (Clark level <4;
Breslow thickness 0.76 - 4mm) because of its significant diagnostic
and prognostic information.
The sentinel lymph node excisional
biopsy provides accurate information about lymphatic drainage
patterns, and allows to make a smaller incision directly over the
identified node, based on the image and the intraoperative gamma
1. Patient preparation -
patients should follow preoperative restrictions if the sentinel node
imaging is performed on the same day as scheduled surgery.
2. Precautions - if the surgery
is to be performed using the intraoperative gamma probe to assist in
finding the sentinel node, the tracer must be injected approximately
0.5 - 3 hours before surgery. If surgery is further delayed
(>6h), another image before surgery is advisable to define further
migration of tracer to additional nodes.
3. Radiopharmaceutical - no
radiopharmaceutical has been specifically approved by the FDA for
lymphoscintigraphy in the U.S. Tc-99m sulfur colloid is used in
a filtered (usually 0.22 mm filtration) or unfiltered form.
Smaller particles are generally recommended as more frequent
visualization of lymphatic channels is achieved with the filtered
Radiology Report: LYMPHOSCINTIGRAPHY
HISTORY; identification of sentinel node for a vertex scalp melanoma.
RADIOPHARMACEUTICAL: 1.08 mCi of 99mTc Sulfur colloid, ultrafiltrated,
injected subdermally in a four quadrant distribution of the scar near
the patient's vertex, in the scalp.
PROCEDURE: Following injection of the radioisotope, dynamic imaging
was performed demonstrating prompt drainage to a sentinel lymph node
identified on the right just behind the ear. This was identified with
both AP and lateral imaging. Flood-filled imaging was also used for
visualization. The patient was sent to the operating room in good
condition with the images.
IMPRESSION: SENTINEL NODE IDENTIFIED IN THE POST-AURICULAR
DISTRIBUTION ON THE RIGHT
DIAGNOSIS FOLLOWING SURGICAL BIOPSY:
A) LYMPH NODE, RIGHT POSTAURICULAR SENTINEL NODE COUNT 6,000,
BIOPSY: NEGATIVE FOR METASTATIC MELANOMA (SEE COMMENT).
B) SKIN AND SOFT TISSUE, SCALP, RE-EXCISION: CHANGES
CONSISTENT WITH PREVIOUS BIOPSY SITE; NEGATIVE FOR
An S-100 immunostain highlights
but there is
no evidence of micrometastases.
A)LYMPH NODE, SENTINEL
A) SENTINEL NODE:
TOUCH PREPS SHOW NO MALIGNANT CELLS.
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