Skin excisional biopsy

Soft Tissue

Skin: Excisional Biopsy

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The goal of excisional biopsy is complete removal of a tumor. An initial shave, punch, or incisional biopsy has frequently, but not always, been performed; therefore, the diagnosis is often known.
Orientation with sutures, clips, or ink is often provided by the submitting physician. Be sure that you thoroughly understand the orientation before proceeding with the gross examination. Call the submitting physician if in doubt.
Measure the skin surface in two dimensions, then the depth of excision. Apply two different colors of ink to the resection margin, parallel to the long axis; for instance, if the long axis runs from medial to lateral, apply black ink to the inferior half and blue ink to the superior half. If the specimen is very large and very deep, you may want to use three colors (one for each peripheral half and one for the deep).
Measure and describe any lesions in terms of color, shape, texture, and borders. Use nomenclature of dermatology. Measure the distance where tumor comes closest to the margin and mention which margin this is. On the cut surface, measure the tumor thickness and distance to the deep margin.
If the specimen has a diameter of 3 mm or less, submit it intact, without cutting it. If the specimen is 4 mm or greater, there are two possible sectioning options:

Perpendicular margins: This is the preferred method. The specimen is serially sectioned (breadloafed), parallel to the short axis. This way, all ink colors appear on every slice, and the distance of tumor to each margin can be measured with accuracy.
En face margins: This method is only indicated when the tumor is >5 mm from the margin macroscopically, or when the specimen is large in which perpendicular margin assessment is impractical (i.e. it would require submission of an excessive number of blocks). The peripheral margins are shaved off and submitted in consecutive order, usually starting from one of the tips (unless the resection has no tips). Be aware that only the most superficial cuts of en face sections are truly representative of the margins; evaluation of deeper cuts may result in margins being falsely called positive. The deep margin may be shaved off and submitted en face as well, or it may remain with the central portion of the specimen, which is serially sectioned parallel to the short axis.

If the specimen is in the shape of an ellipse, it will have two pointed tips. Cut off the tips (keeping their orientation) and bisect them parallel to the longitudinal axis. When this bisected surface is embedded face down, it is possible to see tumor extending to the tips. It can be helpful to ink this bisected surface a specific color (different than the margin colors) and instruct the lab to embed these pieces with that inked surface face down. Submit each tip in its own cassette. Section the central portion of the specimen as described above.