There is a fascinating trend in histotechnology to make manual embedding obsolete by introducing grossing devices that can be used as sectionable blocks during microtomy. Among many others, the main advantage would be the technique when the grossing person is the last participant in the specimen’s orientation before microtomy. There are some methodological and technological problems to solve before automatic embedding becomes the reliable working reality in surgical pathology. There is one publication of preliminary results with plans of clinical studies “to quantify the efficiencies achieved by paraform system” (1).
During 34th NSH Convention at the Trade Show in September 2008, two devices (Tissue-TekR ParaformR Sectionable Cassette System, Sakura Finetek USA, Inc, Torrence, CA and QuickMbedTM silicone sectionable pad, QuickMBed, LLC,Bethesda,MD) were demonstrated for automatic embedding. However, they can be successfully used for manual embedding orientation. This article describes experimentation with these devices for manual embedding in surgical pathology laboratory leaving out assessment of their suitability for automatic embedding.
The ParaformR Sectionable Cassette designated for Tissue- TekR AutoTECR Automated Embedding System has an Orientation type insert (Figure 1). Elastic prongs stick out at the bottom of the cassette. It fits a standard plastic cassette. The lattice bottom allows fluid exchange and paraffin infiltration.
Figure 1. ParaformR Sectionable Cassette inserted in the standard cassette
Device # 2
QuickMBed, LLC distributed only for demonstration and testing a blue silicone pad that has a flexible base and rows of bowling pins like stems with flared ends on the top of the stems. The pad can be placed in a standard plastic cassette. The sectionable pad is intended for needle core biopsies and shaves skin biopsies according to the QuickMBed website (www. quickmbed.com).
Figure 2. QuickMBedTM silicone pad
Figure 2a. QuickMBedTM silicone pad in the processing cassette
Results and Discussion
Device # 1 ParaformR Orientation Cassette
A section of a skin shave biopsy is placed between the prongs of Tissue-TekR ParaformR cassette without a lid. The resilience of the paraform prongs holds the specimen tightly. The device is placed in a regular plastic cassette for processing. The embedding technician has only to pick up the specimen and place face down in the mold with melted wax directly as it is held between the prongs (Figure 3).
Figure 3. Skin shave biopsy in the ParaformR cassette between prongs
Device # 2 QuickMBedTM silicone pad
The Figure 4 shows a prostate needle biopsy core between stems of a flexible silicone pad. The grasp of the stems is completely secure. Even if the pad falls on the floor, the specimen remains at the same place. It looks that the QuickMBedTM flexible silicone pad is very useful for cores and thin specimens.
Figure 4. A prostate needle biopsy core between stems of QuickMBedTM pad.
Flexibility of the pad and stems is beneficial also for more thick specimens. The figure 5 shows a section of skin between the stems.
Figure 5. Skin section between the QuickMBedTMTM pad’s stems
The tips of the skin excision are securely held between the pad’s stems (Figure 6). The embedding person cannot have any doubt how to place the tip in the mold.
Figure 6. Skin excision tips between QuickMBedTM pad’s stems
The presented devices can be used for definite grossing orientation during manual embedding. The simplicity of the procedure and reliability of the devices can make them very useful for histology laboratory practitioners.
Dermatopathology is one area that could definitely benefit from these special embedding orientation devices. For example, a triangle tip of the skin excision can be wrongly placed in the mold down with a non diagnostic side. The line of section in bisected shave or small punch biopsies is often not distinct after paraffin infiltration. The devices can be used for orientation also bigger skin sections, for example micrographic surgery to detect subclinical outgrowths of malignant skin tumors.
Small cervical and gastrointestinal biopsies, especially polyps, also require definite orientation otherwise the most diagnostically valuable areas might be hidden or lost.
Precise embedding orientation is crucial in oral and laryngeal biopsies.
Although core biopsies do not require orientation, sometimes small fragments of them may need a special placement. The described devices can provide better count of cores of prostate needle biopsies. Pathologists and urologist are interested in every fragment of the material because the percent of cancer in the core has clinical importance. New trend in urology, as prostate needle saturation biopsies with cores from 13 to 60 or more and their mapping templates, might find an opportunity for more precise orientation. The devices might even open some options for orientation at the site (“harvest”) of the biopsy, as has been envisioned by the inventors of paraform sectionable cassette back in ninetieth (2).
Larger specimens or sections of them can also benefit from placement in the devices with prongs/stems. There are numerous occasions in surgical pathology grossing when it is necessary to specifically orient the most diagnostically important area. For example, resection margins in breast or intestinal cancer.
Both devices have limitations of their use. For example, very small or amorphous specimens can not be secured between the stems/prongs. Some tubular structures can not also be reliably kept for correct orientation by using these devices.
The design of the devices can be improved to make them more universal. For example, more prongs in the paraform cassette can accommodate different specimens. For the same purpose, the stems in the QuickMBedTM pad can be placed less uniformly. The space for fluids exchange should be bigger, especially in the silicone pad. Microwave assisted tissue processing is sensitive to pads because they absorb fluids and change the mass of the ingredients in the processing chamber. This circumstance should be taken in consideration while using orientation pads in microwave assisted processing.
Although both, Tissue-TekR ParaformR Orientation sectionable cassette and QuickMBedTM silicone sectionable pad were proposed for automatic embedding, either device is a technological advancement for orientation in manual embedding. They certainly can be a useful adjunct in the surgical pathology laboratory practice, especially in dermatopathology and small biopsies embedding orientation. Additional suggestions for improvements will become available as these devices enter into the mainstream histology laboratory.
Unfortunately, OuickMbed abandoned the silicone pad due to legal disputes of patent infringement with Sakura Finetek USA. The domain QuickMBed. com has been deleted. In 2009, QUICKMBED, Inc. filed an international patent application “Scaffold for tissue sample orientation” which comprises hyrdrogel or organogel. It is flexible to permit to be bent, maintains a tissue sample in a particular pre-determined orientation, and not microtome sectionable. The abstract of the patent application states that the substantially liquid component can be replaced during fixation and processing with components that are substantially solid, making the scaffold microtome sectionable, but only a scaffold is not enough for introducing embedding automation. Immobilization of the specimen in the platform ought to be provided. Otherwise the sectionable scaffold is meaningless.
Hopefully, the developer will offer this product for manual embedding orientation.
1. Diederichsen Chris, Whitlatch Stephen: Description and Preliminary Results of a Novel Cassette system (Tissue-Tek Paraform Cassette System). HistoLogic 31(2): 28-30, 1999.
2. Williamsom, IV, Warren P. at al.: Apparatus and method for harvesting and handling tissue samples for biopsy analysis. United States Patent Full-Text Image database: 7156814.
Dimenstein IB: New Devices for Manual Embedding Orientation. The Journal of Histotechnology, 2009, Vol 32 (3): 123-125.