Dear OncoLink "Ask The Experts,"
I recently went to my family practitioner about an odd-looking mole. He said he didn't think it was anything to be concerned about and shaved it off, but then the pathology report identified it as melanoma, Clarks level II and Breslow level 0.49 mm with involved margins. He then sent me to a dermatologist, who performed a wide excision of 2 cm around the margins. This report came back with no cancer. He also obtained panels of the original shave biopsy and had his pathologist read it; they concluded that the first pathologist had actually [incorrectly] read a lot of skin irritation and my melanoma was really a Clarks level I. Can I still have a sentinel node biopsy even though I have had a wide excision?
Christopher J. Miller, MD, Assistant Professor of Dermatology at the Abramson Cancer Center of the University of Pennsylvania, responds:
For a melanoma of this thickness (0.49 mm, Clark's I/II), a sentinel lymph node biopsy would not be appropriate in the absence of other high risk factors (such as ulceration, extensive regression, or vertical growth phase). The presence or absence of these high risk characteristics should be noted on the pathology report. (See Understanding Your Melanoma Pathology Report) If they are not, it would definitely be worth having the slides reviewed by another dermatopathologist who would document these characteristics.
The reason sentinel lymph node biopsy is not indicated for such a thin melanoma (assuming absence of these high risk factors) is that it is highly unlikely that a node would be positive, i.e. show melanoma, in this situation (<1.7% risk, according to Bleicher RJ et al. J Clin Oncol 2003;21:1326-31). With such a low likelihood of obtaining a positive node, I do not think it is worth subjecting the patient to the risks inherent with the procedure.
After a wide excision (2 cm), some surgeons would argue that lymphatic drainage has been disrupted. Therefore, sentinel lymph node biopsy may no longer target the true sentinel node (i.e. the node to where tumor would have been most likely to travel before wide excision).
In summary, I would not recommend sentinel lymph node biopsy. Consultation with a third party dermatopathologist could increase confidence that the diagnosis is accurate.