The increasing use of shave biopsy for diagnosing invasive melanoma in Australia

In reply: We thank Byth and Byth for sharing their perspectives on our article.1 The authors queried whether better equipment and training over the 10‐year period may have had an impact on base transection rates. In fact, our data suggest poorer performance over time, with base transection rates for shave biopsies of 45% (17/37), 55% (32/58) and 56% (45/80) in 2005, 2010 and 2015 respectively (unpublished data).

In the multidisciplinary setting, we commonly encounter a management dilemma when tumours approaching 1 mm in thickness (the threshold for consideration of sentinel node biopsy) have been transected at the base. When uncertainty about depth exists, some surgeons will opt to perform narrow excision to assess residual tumour; however, residual tumour may be destroyed by inflammation and wound healing. Often, the default following base transection is to proceed to sentinel node biopsy, which might have been averted had the true depth been known. Therefore, the immediate cost gain from a more economical procedure is likely overshadowed by larger costs of additional procedures performed to address uncertainties.

Regarding impact on survival, aside from the importance of microstaging for access to medical therapies that provide survival benefit, it must be recognised that pathological diagnosis can be challenging, with up to 9.2% of melanocytic biopsies underinterpreted.2 Adverse consequences of a false negative misdiagnosis are significantly reduced with complete excisional biopsy compared with partial biopsy.3 With the increasing use of shave biopsy and margin involvement, we may indeed start to see an increase in adverse outcomes directly related to this technique.

We agree that clinician intent is important to consider, although this was not possible in a retrospective study. We acknowledge the role of partial biopsy in melanoma diagnosis in situations where primary closure is impractical (ie, large lesions, difficult locations, and patients with significant comorbidities).1 We refer readers to the Australian melanoma clinical practice guidelines for a more detailed discussion on appropriate use of different biopsy techniques.4 While there are situations in which shave biopsy may provide an appropriate alternative to excision, at the population level, this technique is underperforming as a diagnostic biopsy for invasive melanoma. It is inferior to excisional biopsy in achieving two critical objectives: accurate pathological diagnosis3 and adequate estimation of depth.1 Therefore, for most clinically assessed invasive melanomas, we recommend excisional biopsy with primary closure.