About Our Dermatologists
Dr. Diane Kallgren, M.D.
Dr. Diane Kallgren is board certified in Dermatology and a fellow of the American Academy of Dermatology. She graduated Phi Beta Kappa and summa cum laude from The Catholic University of America in Washington, DC, earning her Bachelor’s degree in biology. Dr. Kallgren earned her M.D. from the University of Missouri in Columbia, Missouri. Following medical school, she was an intern at Naval Hospital San Diego and then served as a General Medical Officer for four years in the U.S. Navy. Dr. Kallgren served on board the USS Jason in Hawaii and California and then was stationed at Naval Hospital, Rota, Spain. Dr. Kallgren completed her dermatology residency at the National Naval Medical Center in Bethesda, MD and then served 2 years at Portsmouth Naval Hospital, VA before departing naval service as a Commander and moving to Boulder, CO in 1994. She was a partner at another dermatology clinic in the Boulder area until February 2006 when she founded Kallgren Dermatology Clinic.
An avid runner, Dr. Kallgren also likes to bike, fly fish, hike and garden in her free time. She is married to Kevin Maguire, whom she met while they were both stationed in Spain while in the Navy. They have traveled extensively throughout Africa, South America, and Europe and have many adventures still on their bucket list.
Dr. Cathy Koger, D.O.
Dr. Cathy Koger is a board certified dermatologist and a fellow of the American Academy of Dermatology as well as a fellow of the American Osteopathic Board of Dermatology. Dr. Koger graduated with a BSE in Mechanical Engineering from the University of Michigan and worked as an engineer for over 6 years at Raytheon Systems Company and IBM. In 2003 she was Dr. Diane Kallgren’s running coach through the Bolder Boulder Training Club program. Dr. Kallgren’s love and enthusiasm for medicine and her patients convinced Dr. Koger to retire at an early age from engineering and pursue medical school. In 2006, prior to starting medical school, Dr. Koger was one of the first Medical Assistants at Kallgren Dermatology when Dr. Kallgren first opened her practice. Dr. Koger attended medical school at A.T. Still University in Kirksville, Missouri from 2006-2010. She was accepted into Dermatology Residency at Northeast Regional Medical Center/Cleaver Dermatology from 2010-2014. She specializes in medical dermatology, surgical dermatology, cosmetics, and pediatric dermatology.
In her spare time, Dr. Koger enjoys the outdoors, training, and racing. She has been a runner, cyclist, and triathlete for over 15 years as well as a running/triathlon coach when not in medical school. She also loves spending time with her husband and daughters.
Sue Rancis, PA-C
Susan Rancis has been a Board certified Physician Assistant (PA-C) since 1978 following her graduation from the University Of Colorado Medical Center with a Master’s Degree as a Physician Assistant. Ms. Rancis’ expertise is in the areas of skin cancer screenings, mole evaluation, acne treatment and skin care management as well as sclerotherapy for leg veins, hyperhidrosis treatment and Botox injections. Her particular interest is in helping patients with revitalizing aging skin.
Prior to joining Kallgren Dermatology Clinic, Ms. Rancis practiced general and cosmetic medical dermatology at Lake Loveland Dermatology in Loveland, Colorado. While there, she developed a large patient base by treating patients with various skin disorders which ranged from sun damaged skin, eczema, psoriasis, rosacea and warts as well as nail and hair disorders. She also provided numerous cosmetic treatments including laser procedures and fillers using Restylane, Radiesse and Juvederm.
Prior to this, Ms. Rancis practiced at several clinics on the East Coast and at the University of Colorado.
Sue has worked in dermatology for over 25 years and is one of founding members of the Society of Dermatology Physician Assistants and the Colorado Society of Dermatology Professionals. She has volunteered for the summer children’s “Camp Discovery” which supports children with various dermatologic conditions. Sue has a passion for international outreach and has volunteered her skills by working for medical missions in Mozambique, Vietnam and Mexico.
Brooke W. Lewis, PA-C
Brooke W. Lewis hails from Santa Barbara, California. She attended Vassar College in Poughkeepsie, New York. Upon graduation, she was awarded a fellowship with Princeton University, Princeton in Asia. Brooke worked for two years on the Indonesian island of Java in the town of Yogyakarta teaching English at a local university. She then moved to the island of Timor to open a new Princeton in Asia posting in the town of Kupang on the island of Timor where she worked on public health programs for the nonprofit organization Child Reach. It was through her work with Child Reach that Brooke decided to pursue her passion for medicine.
Upon moving back to the United States, Brooke attended a post baccalaureate pre-med program at Tufts University in Boston. She then attended Chicago Medical School’s PA program and earned a Masters of Science as a Physician Assistant. Brooke moved to Boulder in the summer of 1999 and has worked in dermatology at the Boulder Medical Center, for four years, and then at Boulder Dermatology for eight years before joining the outstanding providers and staff at Kallgren Dermatology in July of 2011.