Skin Shave Biopsy

 

In a shave biopsy, the surgeon’s blade is parallel to the skin surface. The material presents predominately epidermis. Only a superficial portion of the skin is removed. While curetting, as a variant of inadequate shave biopsy, only fragments of disoriented epidermis are obtained. Clinical indication for a shave biopsy: Pigmented lesion Cancer Inflammatory skin disease Degenerative skin disease A shave biopsy has limited value in inflammatory skin diseases, since only a superficial portion of the skin’s dermis is removed. The vast majority shave biopsies are done for pigmented lesions. Depending on the clinical diagnosis the grossing actions are different. To ink or not to ink? In general, the clinician does not ask for margins evaluation even if a pigmented lesion is sent to pathology. Some dermatologists are resentful if a pathologist mentions margins in a shave biopsy unless they specifically ask for them. More, some clinicians become irritated by receiving unsolicited margins evaluation. However, grossing should be open to a possibility of margin’s evaluation. In a shave biopsy, inking provides predominately orientation for embedding if the specimen were cut. In old surgical pathology books, we can find an advice that touching the cut edge with a stick dipped in a dye allows the histotechnologists to identify the cut edge. Recommendation to ink the cut surface might be right in principle, but the straight edge is a pointing mark for embedding anyway. However, technically is easier to ink the entire surgical cut area. While the paraffin makes everything gray, the unstained grossing cut area is the instruction for embedding down in the mold.

If the specimen were cut, it would be appropriate to ink so that the section area would remain unstained. (See the picture below). It might be helpful during embedding.

If the specimen were not cut the inked area would be on the periphery anyway. be on the periphery. If the shave biopsy has an irregular form and requires sectioning, it is also reasonable to ink because there might be difficulties to find the section’s place for correct embedding. Sometimes, it is a challenge to distinguish the surface of the shave biopsy. Hairs are the clue that the surgery cut is at the opposite side that should be inked. If the shave biopsy is translucently thin, the inking is unreasonable because the ink is spread everywhere. In this situation, the specimen also requires additional efforts to prevent curling during embedding. Of course, it is completely unreasonable to ink a skin fragment that was sent with epidermolysis diagnosis (too thin). This shave biopsy usually is sent for frozen section; the regular H&E is done in parallel if there is enough material. To cut or not to cut? If cut, how?The table presents approximate suggestion of inking and cutting depending on the size of the skin fragment.

Size in cm Ink Section How
0.3 or less no no
0.4 – 0.6 yes yes bisection
0.7 – 0.8 yes yes bisection/trisection
0.9 –1.0 yes yes trisection
1.1 – more yes yes trisection

It is convenient to cut on the lid. The polyurethane insert provides the necessary support for the specimen. The blade is cutting through. By the way, this prevents specimen’s switching. In a typical example, there is not any question how to cut: across or along the pigmented area. Obviously along, but the informed decision should be made to present maximum diagnostically valuable material under the microscope. Usually, the samples are irregular form. The area of interest (pigmented zone) is often located eccentrically. The goal is to cut in most informative way. The suggested cuts provide maximal information about the margins although the clinician might not requested the evaluation of them.

The direction of the bisection would be correct as it was maid at two to a left specimen because the pigmented area is located eccentrically as usually it occurs to provide more information. While planning more surgery, if a malignancy diagnosis were maid, the clinician do not request margins evaluation in most case, but the grossing should be done right. This allows the pathologist to make a responsible diagnosis. Satellite mole is sometimes requested by the dermatologist. Two variants look reasonable to present both areas of interest. We have to keep in mind some necessary trimming during microtomy before the diagnostic sections.

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Saucerization

This is a type of shave biopsy that includes a substantial portion of dermis. The sectioning assumes evaluation of margins that requires placement of them in a separate cassette although it is not oriented at the place of harvested biopsy.

Shaves curl in paraffin, especially long biopsies, which are better to cut longitudinally. The flattening can be done in the simplest way between foam pads. However, it is better to put in a slot in a thick foam pad. Constriction of the pad’s threads maintains the skin in flat position. “Debulking” technique close to curetting produces small fragments of epidermis and dermis which cannot be oriented. They are processed and described as in aggregate. There must be measures to prevent the fragment from escaping the cassette during tissue processing (wrapping, mesh cassette, nylon bags or “Histogel” technique). It is a bad idea to place them between sponges because they can be entrapped in the holes under vacuum/pressure conditions in the tissue processor. Embedding During embedding, the epidermis should be oriented away (“up”) from the embedding person. It is a good idea to place the sections at a 45 degree angle if the space in the cassette allows. Correct embedding is crucial in shave biopsies. A skilled histotechnologists is able to figure out the correct line of embedding, however some gadgets can be used to guide the histotech. The way of cutting and inking also gives the necessary information. It seems that the best is to put the biopsy in the foam pad, especially if the margins are very important in the diagnosis, for example in labia margins.   Sometimes dermatologist request margins in a shave biopsy, because the diagnosis might require an extended surgery.  The best way is to put in a incision in a foam pad.

Or very diagnostically chalenging (margins!) labia specimen (below)

Or between plastic pegs in a Sakura Finetek cassette (below).

How many sections in the cassette is appropriate? It is a matter of pathologist’s preference and skills of the histotech in the laboratory. In any event, it is unreasonable to place more than three sections, but better first and foremost due to embedding considerations to avoid tangential section on the microtome. Ophthalmology skin is the most difficult for embedding orientation. The hair that is obviously the superior is the mark for orientation because the opposite side is for embedding down in the mold. Shave biopsies are the most difficult to perform in grossing skin specimens due to many reasons, such as different sizes, uncertain thickness (often very thin), sometimes presence of uncertain lesions, and a possibility of various clinical diagnoses. Despite the shave biopsy specimen’s apparent simplicity, the quality of grossing in dermatopathology is tested in high degree how shave biopsies are processed.

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