We have occasionally used agar en block or partial en block embedding
for resection specimens in order to keep loose tissue, a delicate
or complex surgical margin, or a fenestrated resection plane of
tissue together in Jell-O-like cross-sectional blocks whose entire
or selected areas can be removed intact and then re-embedded in
agar. The largest specimen I have dealt with was a resection of
a DFSP surrounded by friable fatty margins (in about 1985), the
resection being about 20 by 8 by 6 cm. After working two years
with two dermatologists performing Mohs frozen-section-controlled
surgery, we all found that staged permanent-section resection was
much more satisfactory, hugely reducing OR time. To do those, we
receive the oriented stage I excision specimen, use rapid fixation,
and have slides available for interpretation the next (2nd day)
morning. Stage II is scheduled in the office that 2nd day after
lunch, and so forth. But that ended with Dr. Carl Johnson's move to Elante.
We were recently involved in the case (via the hospital
OR) of the resection of a bulbous 26 gram SCC of the bridge and
tip of the nose. The stage I surgery of the bulbous (level 1 resection)
cancer was removed & received after lunch on a Wednesday; then
level 2 margins were removed and arranged on an OR towel with orientation
drawings. The next set were arranged as 7 pieces.
The 3 central deep margin shaves were taken from the towel and
separately embedded. With an orientation description related to
a clock face, the lateral margin pieces were arranged on the grossing
table top...exactly as on the towel...and agar block embedded.
This block was then divided into the four clock face quadrants,
and each quadrant was cone/pie radial cross-sectioned in clockwise
fashion...1-3 cross-sections each turned down 90 degrees onto the
table surface and re-embedded in agar. Lateral margins were found
to be clear, and deep margins positive.
On Friday, a stage 2 surgery removing a deeper plane
(level 3) of tissue (which included cartilage and part of bilateral
nasal vestibules) was effected ,
and the specimen was delivered sutured to a diagram-labeled surgical
towel. It was marked on the deep-aspect (internal) margin with
red dye on the right margin and blue on the left The resection
was placed into a thin plastic weighing dish and specimen submerged
in liquid agar.
Once the agar en block became firmly solid (about 30 minutes),
the container was emptied; and the agar-en-block specimen is noted
en face from the dyed aspectresting
on the towel, viewed from the side resting on metal forceps,
and en face in
my gloved hand from the opposite (vestibular/external) aspect.
This photo then
shows the dividing of the whole block into quadrants ....
Then one quadrant is radially sectioned clockwise............;
then the 6 cross-sections were arranged for two cassettes and
agar re-embedded with co-embedded black agar marker indicating
the beginning point heading clockwise in the block. Level 3 contained
cancer, but the margins were clear.
This method reduces OR time, reduces dermatologist
or plastic surgeon waiting time, reduces or largely eliminates
the need for the less-exacting frozen sections (and thereby eliminates
the huge amount of commandeered time of personnel within the surgical
pathology department). The "grossing" time of the specimen
is increased but performed at a time of the pathologist's own choosing.
Once or twice a year, I use partial en block agar embedding on breast lumpectomy specimens for an area of unstable marginal tissue [L13-2819].
29 November 2003; latest update 23 March 2004; latest addition 11 March 2013) (back
to agar page)