Subjects who carry the diagnosis of seborrheic dermatitis and scalp itch, or controls who don't, (either internally referred through routine visits to outpatient Dermatology clinics at BMC or externally referred from outside providers or who respond to recruitment techniques) will undergo an initial phone screening to review inclusion and exclusion criteria. This screening will involve anonymous screening questions without collection of personal health information. Subjects/controls that meet the criteria to be eligible for the study will then be asked if they are willing to come to BMC for the single study visit. Those subjects/controls that then agree to be scheduled will next be told that we are seeking informed consent by phone for the following minimal risk procedures in preparation for the study visit: