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Dr. Marc D. Sullivan, MD


Dr. Marc Sullivan is a native of Arizona. He earned his degree as Medical Doctor from the University of Arizona, after completing his major in Molecular Cellular Biology and a minor in Finance. His residency was completed at St. Mark's Hospital in Salt Lake City, Utah. He has been a physician for over 10 years and enjoys all areas of family medicine with a special interest in dermatology. He received his passion for medicine from his father who was also a physician. Coming from a family of six, it shouldn't surprise anyone that Marc also has a passion for family. He currently lives in Scottsdale with his wife, Ashley Sullivan, and their 5 children. Even though Ashley is kept very busy with their family, she is still involved, and helps maintain and manage MDS. Both Marc and Ashley take pride in their practice and treat their patients and those they work with the way they would treat their family.  


Marc enjoys snowboarding, golfing, Camping and traveling with his family.

Ali Lewandowski, PA-C


Ali Lewandowski (formerly Johnson) was born and raised in Billings, Montana. She graduated from Montana State University in Bozeman in 2006 with a bachelor’s degree in Cell Biology and Neuroscience. She moved to Arizona in 2007 to attend Midwestern University in Glendale. In 2009 she graduated with a Master’s degree in Physician Assistant Studies. She has been practicing as a Board Certified Physician Assistant in Family Medicine since 2009 in Fountain Hills and Glendale before joining MDS Family Practice. She also works at various Nextcare Urgent Care locations around the valley a few times a month.


Ali enjoys hiking, biking, water sports, travel and spending time with her husband and three kids. 

Ashley Hesher, PA-C


Ashley Hesher is an Arizona native. She was born in Tucson and moved to Phoenix with her family shortly thereafter. She graduated from Arizona State University in 2014 with a Bachelor of Science degree in Psychology. She then attended AT Still University in Mesa, graduating in 2018 with a master’s degree in Physician Assistant studies. She completed a portion of her training at MDS Family Practice and has been working as a Board Certified Physician Assistant ever since.


Ashley enjoys hiking, yoga, camping, traveling, snowboarding, water sports and reading, as well as spending time with her fiancé and their dog.

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