In contrast to thin melanoma (see previous chapter), thick melanomas have an overall worse survival rate. The risk factors are the same as for thin melanoma—fair skin, smoking, sun exposure, multiple moles or nevi, a personal or family history of melanoma, and certain genetic mutations. The thickness of the lesion is crucial to determining prognosis and management. Other factors that determine regional disease include ulceration and a high mitotic rate. This chapter will discuss thick cutaneous melanomas—those >1 mm in thickness.