Martin Mihm, Jr., MD of Brigham and Women's Hospital, Boston, MA gives an overview of his talk on open questions in the histopathology of cutaneous tumors in 2016, which was part of the session on open quesions in dermatopahtology of cutaneous tumors held at the World Congress on Cancers of the Skin (WCCS) and the Congress of the European Association of Dermato-Oncology (EADO) in Vienna, Austria. Prof. Mihm discusses new studies from the last 10 years on 1300 patients of the European Organisation for Research and Treatment of Cancer. They found a difference in survival for patients who have tumor infiltrating lymphocytes at the edge of the tumor; this seems to be a site of great biologic activity and the site of the epithelialmesenchymal transformation (where the tumor goes from the size of a nodule to metastasizing). The patients who have the best survival, are those whose lymphocytes attack this area of the tumor. This was a new finding according to Prof. Mihm. He further discusses the importance of the new drugs, ipilimumab and PD-L1 inhibitor pembrolizumab, for melanoma.