We have occasionally used agar 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.

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.

(posted 29 November 2003; latest update 23 March 2004)         (back to agar page)