Applied Evidence

Biopsies for skin cancer detection: Dispelling the myths

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From The Journal of Family Practice | 2018;67(5):270-274.

References

In addition, time constraints (elliptical excisional biopsies can take up to one hour, especially when a layered closure is performed) and a lack of surgical training may prohibit FPs from performing excisions.

One study found that while dermatologists prefer shave biopsies (80.5%), surgeons prefer excisional biopsies (46.3%) and primary care physicians prefer punch biopsies (44%) for biopsy of a growth suspicious for melanoma.7 In fact, of the biopsies FPs perform, only 29% are of the shave variety.7

However, deep shave biopsies can be performed quickly, with the whole process taking less than 5 minutes. We advocate performing them at the time of presentation, as the evidence shows that deep shave biopsies of suspected melanoma are reliable and accurate in 97% of cases.15

MYTH #3

A partial biopsy can make the cancer spread.

There is no evidence to support that a partial biopsy has any effect on the local recurrence or metastatic potential of malignant melanoma.16 In fact, a biopsy elicits an inflammatory response that activates the patient’s immune system and often causes tumor lysis. Some tumors may even resolve after biopsy. In our clinical practice, we have had several cases of basal cell carcinoma resolve after a biopsy without additional treatment.

MYTH #4

If after performing a deep shave biopsy, tumor or pigment remains, you must leave it because a second biopsy specimen can’t be added to the first.

If pigment is visible after an initial shave or punch biopsy, it is reasonable to obtain additional tissue from the base of the biopsy site. While the deeper tissue cannot be added to the initial specimen for the purposes of Breslow’s depth, it is still helpful for the pathologist to have the sample so that he or she can analyze the tumor cells in the dermis. (Melanoma tumor depth is measured as the maximum distance between malignant cells and the top of the granular layer.17) In these situations, be sure to let the pathologist know that there are 2 specimens in the container.

In general, it is valuable to get as much of the tissue as possible at the time of the initial biopsy. One way to avoid leaving tumor at the base of the biopsy is to look at the base of the biopsy halfway through the saucerization (FIGURE 3). Aluminum chloride can be used for hemostasis if needed to have a clear view. If you see pigment below, angle the blade deeper for the remainder of the biopsy. This method is made easier if you wait at least 10 minutes after injecting lidocaine with epinephrine, which allows the epinephrine to take maximum effect. Management changes when a growth has a depth >1 mm, as it suggests the need for an SNLB, as well as larger margins at the time of definitive surgery (2 cm rather than 1 cm).3

Pausing during a saucerization to look for pigment at the base of the specimen image

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