All our professionals at Atlanta North Dermatology maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in dermatology.

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J. Ellen Koo, MD

Dr. J. Ellen Koo graduated magna cum laude with a biomedical engineering degree from Brown University in 1991. After a year of research in biomedical engineering, she earned her medical degree at Brown University School of Medicine in 1996. After completing a three year residency in internal medicine at Boston University Medical Center, Dr. Koo subsequently completed a three year dermatology residency at the University of North Carolina, Chapel Hill. Prior to starting Atlanta North Dermatology and Skin Care, Dr. Koo practiced in Buckhead for five years, where she specialized in medical, surgical and cosmetic dermatology. Dr. Koo is on active staff at Piedmont Hospital, Atlanta, GA.

Dr. Koo is board certified by the American Board of Dermatology and the American Board of Internal Medicine. During her residencies, she has made multiple presentations at both local and national conferences concerning various topics.

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Kimberly Nicholson, MD

Dr. Kimberly Nicholson is originally from central Florida, where she completed her undergraduate degree in Interdisciplinary Natural Sciences and graduated summa cum laude at the University of South Florida in 2003. She then moved to Atlanta where she received her medical doctorate from Emory University School of Medicine in 2007. Following her medical training, she completed an internship in Internal Medicine as well as a residency in Dermatology at Northwestern University in Chicago, IL, where she also served as chief resident. She pursued additional subspecialty training in dermatopathology at the University of Texas M.D. Anderson Cancer Center before settling in Sandy Springs, GA. Prior to joining Atlanta North Dermatology, Dr. Nicholson practiced dermatopathology for three years in the Atlanta area. Dr. Nicholson is on staff at Piedmont Hospital in Atlanta and is board certified by the American Board of Dermatology in both dermatology and dermatopathology.

During both her training and practice, Dr. Nicholson has been actively involved in multiple professional organizations as well as the Atlanta dermatology community. She is the author of several publications and has lectured both locally and nationally on various topics, including cutting edge techniques for the diagnosis of melanoma. She specializes in general dermatology and dermatologic surgery, and has a particular interest in medical dermatology and melanoma. In addition to her professional career, she enjoys spending time with her husband and four children, and is an avid sports enthusiast.

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Larissa Chismar, MD

Dr. Larissa Chismar graduated summa cum laude from Northwestern University. Larissa attended and graduated from medical school and completed her dermatology residency at the prestigious Albert Einstein College of Medicine in New York. She subsequently completed a dermatopathology fellowship at the same school, and practiced in that dermatologic field for two years at one of the largest dermatopathology practices in Atlanta, prior to joining Atlanta North Dermatology.

Dr. Chismar is fully board certified by the American Board of Dermatology in both dermatology and dermatopathology. She is a fellow of the American Academy of Dermatology and is a member of the Atlanta Association for Dermatology and Dermatologic Surgery and the Georgia Society of Dermatology and Dermatologic Surgery. She is the author of multiple publications and has given presentations at local and national conferences. She specializes in general dermatology with an interest in medical dermatology. Dr. Chismar resides in metro-Atlanta with her husband, a professional musician with the Georgia Symphony Orchestra, and their son.

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Brandon Merrill, MD

Dr. Brandon Merrill is a board certified general dermatologist and Mohs surgeon and a member of the American Academy of Dermatology.

Prior to joining Atlanta North Dermatology, Dr. Merrill completed a three year general dermatology residence at the University of Missouri, where he served as chief resident during his final year. Following completion of his general dermatology residency, Dr. Merrill continued his training at the University of Missouri, completing an American College of Mohs Surgery accredited fellowship in Mohs Micrographic Surgery and Dermatologic Oncology.

Dr. Merrill graduated magna cum laude from Georgia Southern University, and completed medical school near the top of his class at Mercer University School of Medicine, where he was elected into the Alpha Omega Alpha honor medical society.

Dr. Merrill has authored several general dermatology and dermatologic surgery publications. In addition to his specialization in Mohs surgery, Dr. Merrill also has particular interest in general dermatology, surgical dermatology and reconstructive surgery.

Dr. Merrill lives in metro Atlanta and enjoys going to Braves games with his wife and daughter.

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T.J. Chao, MPAS, PA-C

T.J. Chao is a Certified Physician Assistant with over 18 years of Dermatology experience and 21 years of health care experience. T.J. graduated magna cum laude from the University of Florida in 1997 with a bachelors degree in nursing. He worked for three years in emergency and critical care medicine as a registered nurse. T.J. went on to earn a Masters degree in the Physician Assistant Program at the University of Florida, graduating at the top of his class in 2000.

T.J. Chao has practiced as a Dermatology Physician Assistant in the metro-Atlanta area since 2000. During this time, he has developed expertise in both general and cosmetic dermatology. T.J. has also developed an expertise in the treatment of psoriasis, and has published several articles in various scientific journals, as well as given numerous lectures at regional and national medical conferences. He joined our practice in May 2011.

T.J. has served as a Trustee and President of the Georgia Dermatology Physician Assistants. He currently serves on the GDPA board as the Immediate Past-President. He is also a member of the Society of Dermatology Physician Assistants, American Academy of Physician Assistants and Georgia Association of Physician Assistants. TJ is fluent in Spanish. He lives in Marietta with his wife and three children and enjoys coaching baseball, basketball, football and other sports.

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Katie Covington, MPAS, PA-C

Katie Covington is a Certified Physician Assistant. She obtained her bachelors degree, with high honors, from Emory University in 1998, having attended Emory on a four year academic scholarship. She earned her Masters Degree in Medical Science at Emory in 2001, graduating again with High Honors, as well as receiving Distinctions from Emory during each year of her study.

After graduation, Katie practiced Primary and Urgent Care medicine in a family practice and in an emergency department for five years. Katie has practiced exclusively in dermatology since 2006 and has developed an expertise in treating a wide variety of skin disorders with patients of all ages. Katie is a member of the Phi Beta Kappa Honor Society, the Georgia Dermatology Physician Assistants, the Society of Dermatology Physician Assistants, the American Academy of Physician Assistants, and the Georgia Association of Physician Assistants. Katie resides in Roswell with her husband and 3 children.