In a Pinch? Rocker-Slide Punch Biopsy Technique

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The authors present a novel approach to a punch biopsy when the desired punch size is unavailable, a smaller defect is desired, or a more elliptical wound is preferred vice a circular defect, thereby producing a superior cosmetic outcome. In recent years, elliptical punch biopsies have been introduced1; however, such alternatives pose difficulties as they increase the force required for an appropriate biopsy depth (17 lbs vs 4.3 lbs for conventional circular punch) as well as increase cost (approximately 10 dollars vs 2 dollars for conventional circular punch).2 An optimal punch would harness the decreased force required of a circular punch due to its rotational cutting potential while creating an elliptical wound. The ability to create an elliptical wound when skin is stretched perpendicular to skin tension lines is possible3,4; although, typically small dog ears remain on either end.1,2 Additionally, there are many circumstances, especially in resource-limited environments, where the correct size punch may not be available.
Thus, the authors have successfully implemented the rocker-slide punch biopsy technique. The punch is placed almost parallel to the skin edge and hooked with an angled punch while not quite penetrating to full depth. Once secure in the skin, using the initial edge as an anchor, the instrument is slid toward the opposite end of the specimen. Additional pressure may be placed on the opposite end to gather more tissue. Once the cutting edge of the punch instrument surrounds the lesion, it is sunk to full depth with a twisting circular cutting motion. The resulting tissue is elliptical in shape with a smaller ratio of width to length making closure easier. The figures demonstrate 2 lesions, a hyperpigmented papule next to a pink papule, which are both next to the most appropriate punch, a 6 mm punch (Figure 1A). Although a 6 mm punch captures the lesions without difficulty, a 5 mm punch (Figure 1B) using the rocker-slide technique also captures both lesions (Figure 2 demonstrates this in a clockwise fashion from the upper left to the lower left). The resulting wound was approximately 4 × 8 mm (ratio of 1:2, which is closer to optimal 1:3),5 and the specimen's diameter was 6 mm. This technique allows for removal of less normal tissue during the biopsy process. Theoretically, the area of a 6 mm circle is 28.3 versus 25.2 mm2 for the calculated ellipse based on the wound dimensions in this example.4 This equates to an 11.1% decrease in normal skin sampled compared with a standard circular biopsy. Because of the tissue's inherent elastic nature, multiple factors beyond the scope of this article contribute to wound shape and size, which may render this calculation less accurate. The authors recommend considering this technique when in a pinch; it allows for increased adaptability, potentially decreases the amount of normal tissue sampled, and favors maximal cosmesis. Please see Supplemental Digital Content, Video,
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