Do you recommend an additional procedure for melanomas if there is tumor within 1-2mm of the margin?  

Yes, for most invasive melanomas. For melanoma in situ, I often measure the distance between the tumor and the margin and add that information to the dermatopathology report. In certain anatomical locations (near eye, nose, ears, digits, genitals) or certain clinical situations, 2mm of clear margin...

My understanding has been that a re-excision of melanoma is based on initial Breslow depth. As long as the margins are clear on that re-excision, regardless of being 1-2 mm away from any one edge, there is no indication for additional surgery. 

I agree that there are varying approaches to an excision or an excisional biopsy that returns with clear margins for melanoma. What we usually do is make sure that the excision margins match the appropriate breslow depth. For example, if a melanoma in situ was removed with a 2 mm margin then going b...