Instructions for use of The Davidson Marking System® Dyes
To download these instructions in pdf format, click here.
The Davidson Marking System® dyes are used to orient surgical and other tissue specimens submitted for histopathology. Other applications have been discovered as well.
NEVER APPLY ANY OF THE DAVIDSON® DYE MATERIALS TO A LIVING PATIENT! Only use them on tissue which has been removed. These are pigments which if placed in the living tissue could cause permanent coloration.
There are a variety of uses for these dyes. None should be tried without appropriate laboratory investigation first.

The normal application of the Davidson® dyes is to mark the surgical tissue margins. The dyes are most effective when applied to fresh tissue, but work well when applied to tissues already fixed in formalin. Fresh tissue should be patted dry. Fixed tissues should be wiped gently to remove the fluids covering the tissue surfaces. The dyes can be applied in a variety of fashions. Many have found it useful to use wooden orange sticks. The stick is dipped into the dye, the orange stick is scraped along the bottom, excess fluid is removed from the stick by touching it to the top of the bottle and the side of the stick is applied to the appropriate tissue margin. If large surfaces are to be dyed, a cotton-tipped applicator is often useful. This too can be dipped into the dye and then the dye painted on the tissue surface.

Always shake the bottle prior to use.

The dyes require 2 to 5 minutes to bond to the tissue surface and should be left alone for this period of time. It is not necessary to dry the tissue (such as with a hair dryer). Simply allowing them to sit in the open air is sufficient. The tissue can then be placed in a cassette and put in formalin for permanent fixation or can be placed on a chuck and prepared for frozen section. Only small amounts of dye are necessary for effective marking.

After use, the caps should be kept on the bottles, for when the materials dehydrate they will become ineffective. Do not dilute or attempt to reconstitute the dyes.
Note on Processing Fatty Tissue

Adherence of marking dyes to fatty tissue, especially for frozen sections, can be a challenge. A recent observation by Brian Datnow, M.D., a pathologist at UCSD, improves this issue. The tissue surface can be defatted with acetone prior to dye application. Squirt or spray a little acetone from a squeeze bottle onto the tissue surface. pat dry and then applyt he dyes and process in the usual fashion, both for frozen and permanent sectioning. This is especially effective for breast and subcutaneious tissues.
The following represents a typical MOHS marking application. Imagine a 2cm diameter circular piece of skin removed in the excision of a skin cancer (as noted in the illustration below). The tissue is cut into 4 appropriate-sized pieces and prepared for frozen section. The pathologist maintains precise orientation for each piece of tissue. The dyes are applied to the various tissue surfaces and a map is made documenting this application and orientation. Different symbols are used for each color. It is best to develop a consistent set of symbols. Commonly used symbols are shown in the figure below. Click here for a step by step example for tissue orienting.
For more guidelines about marking and mapping for orienting tissue, click here.
Bradley Products has developed a "Path Sheet" that may be helpful for mapping the orientation as you mark the tissue. To download the Path Sheet, click here.
An alternate application system is to put an ounce of dye into a small plastic squeeze bottle such as those that contain oil for oil immersion microscopy. The dye can then be placed on the tissue simply by squeezing the bottle and rubbing the tip of the spout along the tissue.

The principal application for the Davidson Marking System® dyes is to assist in the orientation of surgical specimens. While the dyes are useful in marking the surface of any surgical specimen, many have found the multiplicity of colors superior to a single color. There appears to be a wide variation in color preference, in part due to personal preferences, and in part due to variability in the adherence of the dyes to fixing chemicals and techniques, as these vary from one laboratory to another.

Another interesting application for the multi-color marking dyes is the ability to process multiple specimens in a single cassette. For example, if several skin tags are removed and one chooses to examine all of them microscopically, each can be dyed a different color, all placed in a single cassette, and processed as a single specimen. The cost savings is obvious. Before using the dyes for this application, each laboratory should validate the consistency of the dyes in their own institution. While it seems prudent to use this concept on multiple benign skin lesions where the probability of malignancy is very small, it would not seem wise to use this application to process specimens with a high probability of malignancy.

Surely there are many interesting and useful applications for the Davidson Marking System® dyes. Each new application must be carefully explored prior to general recommendation. If questions, problems, or ideas arise, please contact us.