9 tips to help prevent derm biopsy mistakes

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Applied Evidence

9 tips to help prevent derm biopsy mistakes

J Fam Pract. 2014 October;63(10):559-564

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References

1. Pickett H. Shave and punch biopsy for skin lesions. Am Fam Physician. 2011;84:995-1002.

2. Alguire PC, Mathes BM. Skin biopsy techniques for the internist. J Gen Intern Med. 1998;13:46-54.

3. Fernandez EM, Helm T, Ioffreda M, et al. The vanishing biopsy: the trend toward smaller specimens. Cutis. 2005;76:335-339.

4. Hieken TJ, Hernández-Irizarry R, Boll JM, et al. Accuracy of diagnostic biopsy for cutaneous melanoma: implications for surgical oncologists. Int J Surg Oncol. 2013;2013:196493.

5. Scolyer RA, Thompson JF, McCarthy SW, et al. Incomplete biopsy of melanocytic lesions can impair the accuracy of pathological diagnosis. Australas J Dermatol. 2006;47:71-75.

6. McCarthy SW, Scolyer RA. Pitfalls and important issues in the pathologic diagnosis of melanocytic tumors. Ochsner J. 2010;10:66-74.

7. Swanson NA, Lee KK, Gorman A, et al. Biopsy techniques. Diagnosis of melanoma. Dermatol Clin. 2002;20:677-680.

8. Chang TT, Somach SC, Wagamon K, et al. The inadequacy of punch-excised melanocytic lesions: sampling through the block for the determination of “margins”. J Am Acad Dermatol. 2009;60: 990-993.

9. Bichakjian CK, Halpern AC, Johnson TM, et al; American Academy of Dermatology. Guidelines of care for the management of primary cutaneous melanoma. American Academy of Dermatology. J Am Acad Dermatol. 2011;65:1032-1047.

10. Pardasani AG, Leshin B, Hallman JR, et al. Fusiform incisional biopsy for pigmented skin lesions. Dermatol Surg. 2000;26:622-624.

11. King R, Hayzen BA, Page RN, et al. Recurrent nevus phenomenon: a clinicopathologic study of 357 cases and histologic comparison with melanoma with regression. Mod Pathol. 2009;22:611-617.

12. Mills JK, White I, Diggs B, et al. Effect of biopsy type on outcomes in the treatment of primary cutaneous melanoma. Am J Surg. 2013;205:585-590.

13. Stell VH, Norton HJ, Smith KS, et al. Method of biopsy and incidence of positive margins in primary melanoma. Ann Surg Oncol. 2007;14:893-898.

14. Egnatios GL, Dueck AC, Macdonald JB, et al. The impact of biopsy technique on upstaging, residual disease, and outcome in cutaneous melanoma. Am J Surg. 2011;202:771-778.

15. Ackerman AB, Boer A, Bennin B, et al. Histologic Diagnosis of Inflammatory Skin Disease: An Algorithmic Method Based on Pattern Analysis. New York, NY: Ardor Scribendi; 2005.

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An advantage of the punch biopsy is that patients are left with linear scars rather than round, potentially dyspigmented (darker or lighter) scars that are often associated with shave biopsy. A well-sutured punch biopsy can be cosmetically elegant, particularly if closure is oriented along relaxed skin tension lines. For this reason, punch biopsies are well suited for cosmetically sensitive locations such as the face, although shave biopsies are also often performed on the face.

4. Choose an excisional biopsy for a melanocytic neoplasm, when possible.

The purpose of an excisional biopsy (which typically includes a 1 to 3 mm rim of normal skin around the lesion) is to completely remove a lesion. The excisional biopsy generally is the preferred technique for clinically atypical melanocytic neoplasms (lesions that are not definitively benign).^4-8

When suspicion for melanoma is high, excisional biopsies should be performed with minimal undermining to preserve the accuracy of any future sentinel lymph node biopsy surgeries. Excisional biopsy is the most involved type of biopsy and has the largest potential for cosmetic disfigurement if not properly planned and performed. While guidelines from the American Academy of Dermatology state that “narrow excisional biopsy that encompasses [the] entire breadth of lesion with clinically negative margins to ensure that the lesion is not transected” is preferred, they also acknowledge that partial sampling (incisional biopsy) is acceptable in select clinical circumstances,⁹ such as when a lesion is large or on a cosmetically sensitive site such as the face.¹⁰

While a larger punch biopsy (6 or 8 mm) or even deep shave/saucerization may function as an excisional biopsy for very small lesions, this approach can be problematic. For one thing, these biopsies are more likely than an excisional biopsy to leave a portion of the lesion in situ. Another concern is that a shave biopsy of a melanocytic lesion can lead to error or difficulty in obtaining the correct diagnosis on later biopsy.¹¹ For pathologists, smaller or incomplete samples make it challenging to establish an accurate diagnosis.¹² Among melanomas seen at a tertiary referral center, histopathological misdiagnosis was more common with a punch or shave biopsy than with an excisional biopsy.⁹

It has been shown that partial biopsy for melanoma results in more residual disease at wide local excision and makes it more challenging to properly stage the lesion.^13,14 If a shave biopsy is used to sample a suspected melanocytic neoplasm, it is imperative to document the specific site of the biopsy, indicate the size of the melanocytic lesion on the pathology requisition form, and ensure that all (or nearly all) of the clinically evident lesion is sampled. Detailing the location of the lesion in the chart is not only essential in evaluating the present lesion, but it will serve you well in the future. Without knowing the patient’s clinical history, benign nevi that recur after a prior biopsy can be difficult to histologically distinguish from melanoma (FIGURE 3). For more on this, see tip #7.

5. Be careful with curettage.

Curettage is a biopsy technique in which a curette—a surgical tool with a scoop, ring, or loop at the tip—is used in a scraping motion to retrieve tissue from the patient. This type of biopsy often produces a fragmented tissue sample. Its continued use reflects the speed and simplicity with which it can be done. However, curettage destroys the architecture of the tissue of the lesion, which can make it difficult to establish a proper diagnosis, and therefore is best avoided when performing a biopsy of a melanocytic lesion (FIGURE 4).

6. Remember the importance of proper fixation and processing.

As obvious as it may sound, it is important to remember to promptly place sampled tissue in an adequate amount of formalin so that the tissue is submersed in it in the container.¹⁵ Failure to do so can result in improper fixation and will make it difficult to render an appropriate diagnosis. Conventionally, a 10:1 formalin volume to tissue volume ratio is recommended. If the “cold time”—the amount of time a tissue sample is out of formalin—is long enough (greater than a few hours), an appropriate assessment can be impossible.

Appropriate fixation and fixation times are important because molecular testing is being increasingly used to make pathological diagnoses.¹⁶ Additionally, aggressively manipulating a biopsy sample while extracting it or placing it in formalin can cause “crush” artifact, which can limit interpretability (FIGURE 5).

7. Properly photograph and document the biopsy location.

When performing a biopsy of a suspicious neoplasm, physicians often remove all of the lesion’s superficial components, which means that at the patient’s follow-up appointment and subsequent treatments, only a well-healed biopsy site will remain. The biopsy site may be so well healed that it blends seamlessly into the surrounding skin and is nearly impossible for the physician to identify. This problem is seen most often when patients present for surgical excision or Mohs micrographic surgery.¹⁷