Warthan Dermatology Find A Doctor Directions. Warthan Dermatology. 181 N Ridge Rd Ste 100 McKinney, TX 75071 United States (972) 542-4646. Directions. 33.2002927, -96.6997255. Talk to Us. For more information about Southwestern Health Resources or to find out more about our healthcare options. ... Patient Portal (MyChart).