Martin Mihm, Jr., MD of Brigham and Women's Hospital, Boston, MA gives an overview 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 held the first talk [overview available in a separate video]. First, he discusses the talk by Dr Klaus Busam about the diagnosis of desmoplastic melanoma; this tumor presents as a firm hard nodule like a scar. Dr Busam further discussed the use of molecular techniques to look for mutations that help to make a differntial diagnosis. The reason that a correct diagnosis is important is that desmoplastic melanoma is a lesion that recurs locally and can go along nerves, in the head and neck and even into the brain. The second talk Prof. Mihm discusses was by Dr Raymond Barnhill on spitzoid melanocytic neoplasms. The spitzoid lesions were originally described as melanoma in childhood as they were thought to occur in children and to be benign. It is now known that there is a spitz lesions that can be excised and does not recur. However, there are variants, which have been problematic. Dr Barnhill reviewed the field and the best course is to realize that these lesions are not black and white; some may be borderline lesions and should be excised, and rarely, lesions can metastesize. Finally, Prof. Mihm discusses the talk by Dr Arthur Sober on staging of Merkel cell carcinoma. Merkel cell carcinoma is a very rare tumor but it is very aggressive. In the new staging system, a large population of patients was analyzed. They found that lesions that present without any evidence of mitosis, have a good survival whereas if they have a node, survival falls; and if they have metastatic diseae, the survival is much worse. The talk gave a detailed understanding of how to better stage the lesions in order to look for better treatments for them according to Prof. Mihm.