Physician Profiles

Douglas C. Semler, MD, FAAD

Dr. Semler is a board certified dermatologist and dermatologic surgeon. He is an active member of the American Academy of Dermatology.

Dr. Semler earned his Bachelor of Science degree, magna cum laude, from the University of Michigan. He obtained his medical degree from the University of Cincinnati College of Medicine, where he was a member of the Alpha Omega Alpha medical honor society. He completed his internship and dermatology residency at Case Western Reserve University, serving as Chief Resident in his final year.

Dr. Semler is a staff physician at INOVA Loudoun Hospital.


Shannon Whitlock, PA-C

Shannon Whitlock is a certified physician assistant (PA-C) specializing in dermatology. She is a member of the American Academy of Physician Assistants and the Society of Dermatology Physician Assistants.

Shannon received her Master of Health Science degree from The George Washington University graduating from its Physician Assistant Program with honors (Alpha Eta Honor Society).

As a physician assistant Shannon is certified to diagnose and treat dermatological conditions, order and interpret tests and prescribe medications. In addition to treating acute and chronic conditions she performs skin cancer screenings, biopsies, surgical excisions, cryotherapy and cosmetic procedures.


Laurel Lan, PA-C

Laurel is a native of the Washington, D.C. area, growing up in Montgomery County, Maryland. She received her Bachelor of Science degree in Human Biology from Brigham Young University and was recognized with the College of Biology Academic Achievement Scholarship. Ms. Lan then completed her Masters degree from the George Washington University Physician Assistant Program, graduating in the top 1% of her class, receiving the PA Alumni Outstanding Student Scholarship and was inducted into the Alpha Eta Honor Society.

Following her graduate program, Laurel trained with the Department of Rheumatology at Children’s National Medical Center. She then returned to George Washington University to formally train in dermatology, and later trained for 2 years in private practice with an assistant clinical professor in the Department of Dermatology at Columbia University/New York Presbyterian Hospital as her mentor. She then worked in private practice in Gainesville, VA, and now has a cumulative experience of 11 years in the practice of dermatology.

Ms. Lan is board certified by the National Commission on Certification of Physician Assistants, and is a member of the American Academy of Physician Assistants. She is experienced in performing total body skin examinations, detecting and treating skin cancers, as well as diagnosing and treating other maladies such as rashes, acne, and warts. She also has many years of experience performing cosmetic and laser procedures.

Laurel is proud to join Dr. Semler and Shannon in providing quality and compassionate care to the patients of Semler Dermatology. In her spare time, she enjoys spending quality time with her family, hiking, and competitive running, once placing in the top 100 overall women in the Boston Marathon. She resides in Ashburn, Virginia with her husband, Steve, a pediatric dentist, and their children, Ethan, Camden, and Clara.