Page Content

Meet The Faculty

Mayo Clinic Dermatology Residency leadership team in Minnesota

The Department of Dermatology at Mayo Clinic's campus in Rochester, Minnesota, offers a full range of dermatologic care for both common and rare problems related to skin, hair, nails, and mucous membranes.

Mayo Clinic has more than 44,000 dermatology outpatient visits each year. The inpatient dermatology service at Mayo Clinic Hospital, Methodist Campus, cares for more than 400 patients annually. Some of these patients have unusual or complicated dermatologic problems and are referred by their physicians, but many are self-referred.

The department's 33 board-certified physicians are experts in medical, surgical, and pediatric dermatology. All have full-time appointments in the department.

In addition to caring for patients in their clinical practices, faculty members are committed to teaching and facilitating the growth of medical knowledge. Many faculty members have published and lectured extensively and are well-regarded in their specialized fields. Residents have direct access to faculty throughout the Dermatology Residency.

From the program director

A video message from our director


A video message from our director

Megha M. Tollefson, MDWelcome to Mayo Clinic's Dermatology Residency program in Rochester, Minnesota!

I am a pediatric dermatologist and a graduate of Mayo Clinic's Dermatology Residency program. I am proud to be able to educate and advocate for current and future residents in the best training program in the country.  

I came to Mayo for medical school many years ago, never expecting to stay. This is not an uncommon story that people here have, coming for training but then being so blown away by the institution, people, and culture of patient-first care that they end up staying. My four years have turned into more than 20. Training at Mayo Clinic is a special experience.

One of the greatest strengths of training at our program is the clinical experience. Our residents are able to take care of patients from the community, the surrounding states, across the nation, and throughout the world, learning both common and complex dermatologic conditions. 

Patient care is at the heart of not only our training program but also the institution, which lives by the words “the needs of the patient come first.” A hallmark of Mayo Clinic is the incredible sense of collegiality and collaboration, and our residents are able to experience that first-hand every day.

In our program, residents are able to learn from renowned specialists in all aspects of dermatology — complex medical, pediatric, Mohs, and dermatopathology. Our program is rigorous and clinically robust. Our system of graduated autonomy trains our residents to go out into practice with the ability to take the best care of their patients. Graduates are well-known to be excellent clinicians and patient advocates and are well-prepared for practice whether it be in the community or in academics.

Every day I am impressed by the incredible physicians and people our residents are, and I invite you to come learn more about us!

Megha Tollefson, M.D.
Dermatology Residency Program Director
Professor of Pediatrics
Associate Professor of Dermatology

Core faculty

Katelyn Anderson, M.D.

Katelyn Anderson, M.D. (she/her)

Dr. Katelyn Anderson is an Assistant Professor of Dermatology and Pediatrics at the Mayo Clinic College of Medicine and a Senior Associate Consultant in the Department of Dermatology. After attending medical school at the University of Iowa Carver College Of Medicine, she came to Mayo Clinic for pediatric residency and found herself here to stay! She went on to complete a dermatology residency and a pediatric dermatology fellowship at Mayo Clinic and was delighted to join the staff thereafter. Her clinical and research interests include vascular tumors and malformations, atopic dermatitis, and cutaneous diseases in pediatric organ transplant patients.


Dr. Anderson is a member of the Mayo Dermatology Education Committee and is enthusiastic about resident and medical student wellness, education, and mentorship. She has enjoyed partnering with the residents to organize the annual dermatology resident-staff fitness challenge! Outside of medicine, Dr. Anderson is a busy mother of three, and enjoys distance running, watching the newest Netflix series, and spending time with her husband and children.


View full profile

Hafsa Cantwell, M.D.

Hafsa Cantwell, M.D. (she/her)

Dr. Hafsa Cantwell (Huhf-sa) is one of our medical dermatology faculty. She grew up in the Boston area, then headed midwest to attend medical school at the Mayo Clinic School of Medicine in Rochester, MN. In awe of the immense resources and the unique culture at Mayo Clinic, she decided to stay for dermatology residency. She was thrilled to join the faculty after graduation! Dr. Cantwell especially enjoys her time on the hospital service. Her clinical interests include skin of color dermatology, alopecia, autoimmune blistering disease, and aesthetic dermatology.


When not in clinic, she may be found working out at the DAHLC, enjoying a concert in Minneapolis, or trying a new homemade ice cream recipe with her husband.


View full profile

Mark Davis, M.D.

Mark Davis, M.D. (he/him)

Dr. Mark Davis is Chair of our Department of Dermatology. He hails from Ireland where he graduated from the Royal College of Surgeons and then completed 4 years of training in internal medicine in Dublin. The Mayo Clinic had a massive international name in Ireland, and wanting to get the best further training he could, he moved to Minnesota and completed an internal medicine residency at Mayo Clinic. He then decided on a career in Dermatology, and applied for and was accepted to dermatology residency and additionally the clinician investigator track with 2 years of training in research. In 1997 he joined the consultant staff at Mayo Clinic. The years have flown by.


Outside of work Dr. Davis enjoys meeting colleagues at national and international meetings, traveling the world to see family and friends, CrossFit at 5 a.m. when he can make it, skiing, music of all kinds, and theater (which is incidentally terrific in Minneapolis).


What's the best thing about our work?

"Working with great colleagues not only in dermatology but across disciplines is what inspires me daily. We see patients from every walk of life with conditions that vary from straightforward to complex and life-threatening. If you need help with any aspect of care or to get the opinions of colleagues they are available. There are so many exciting things happening in the department to move our discipline forward, including engagement in AI, digital dermatopathology, new techniques in surgery, our center for esthetic medicine and surgery, our cross-disciplinary research, and our exceptional education programs. All with a firm focus on the needs of the patient being central to everything we do."


View full profile

Addison Demer, M.D.

Addison Demer, M.D. (he/him)

Dr. Addison Demer is one of our newest Mohs surgeons and will serve as Director of Derm Surgery Resident Education starting July 2022. He grew up in the Twin Cities where he trained at the University of Minnesota. Dr. Demer has research and clinical interests in special-site cutaneous melanoma, high-risk non-melanoma skin cancer, and reconstruction. His favorite part of life at Mayo is working closely with the residents and fellows, and teaching.


Outside of work, Dr. Demer can often be found out on the Whitewater State Park hiking trails with his wife and 3 kids, “ripping it up” on his Onewheel, snowboarding, camping, boating at the cabin, or doing any number of active hobbies. When not on-the-go, you may find him with a burrito or ice cream cone in hand watching Netflix.


View full profile

Julio Sartori-Valinotti, M.D.

Julio Sartori-Valinotti, M.D. (he/him)

Dr. Julio Sartori-Valinotti (Who-leo) is our Assistant Program Director and an Assistant Professor of Dermatology and Medicine. He attended medical school in Asuncion, Paraguay, and completed a residency in internal medicine before moving to the U.S. After a postdoctoral fellowship at the University of Mississippi Medical Center, he joined Mayo Clinic for internal medicine residency, followed by dermatology residency and dermatopathology fellowship. Dr. Sartori-Valinotti is passionate about resident education and well-being. His clinical interests include complex medical dermatology, psoriasis, hospital dermatology, and teledermatology.


Outside of medicine, Dr. Sartori-Valinotti enjoys spending time at the gym, traveling, attending sports events with his family, watching superhero movies, and eating burgers and ice cream.


View full profile

Megha Tollefson, M.D.

Megha Tollefson, M.D. (she/her)

Dr. Megha Tollefson (no “n” at the end) is our Residency Program Director and also serves as our Pediatric Dermatology Fellowship Director. She grew up in a few places around the country but considers the Bay Area in California to be home (even though she has lived in Rochester longer!). She left the Bay Area to come to Mayo first for medical school, then for residencies in pediatrics and dermatology, before completing her pediatric dermatology fellowship back in California, and then returning to Mayo to join the faculty as a pediatric dermatologist. In the clinical setting, you can often find Dr. Tollefson discussing all things pediatric dermatology, but especially complex vascular malformations patients. She is passionate about providing interdisciplinary care, furthering pediatric dermatology research, and all things education.


Outside of work you can find her riding her indoor exercise bike (also popularly known as “the bike that goes nowhere”), traveling to new places with her family, or exploring the latest restaurants.


View full profile

Carilyn Wieland, M.D.

Carilyn Wieland, M.D. (she/her)

Dr. Carilyn Wieland (like ‘Carolyn’ but with an ‘I’, WEE-land) is our Associate Program Director and also serves as our Dermatopathology Fellowship Program Director. She grew up in northwestern Illinois and attended medical school at the University of Chicago before coming to Mayo Clinic for dermatology residency and dermatopathology fellowship. A summer research experience as an undergraduate introduced her to the amazing resources and culture at Mayo Clinic, and these opportunities and environment inspired her to return for residency. She has been on faculty ever since! Dr. Wieland especially enjoys discussing cases that require clinical and pathologic correlation with residents and promoting topics of equity and diversity in dermatology. Her clinical and academic interests include autoimmune blistering disease, alopecia, and digital pathology.


Outside of work you might find her training for her next half marathon (or maybe even cross country skiing in the winter), taking care of her chickens, or enjoying her favorite local Pho with her family.


View full profile

Molly Youssef, M.D.

Molly Youssef, M.D. (she/her)

Dr. Molly Youssef is a Medical Dermatologist who also has training in Pediatric Dermatology. She grew up on a farm in southeastern Minnesota and attended medical school at the University of Minnesota. She completed pediatric residency at Mayo Clinic and during that time, she discovered a passion for dermatology. She subsequently completed dermatology residency at the Medical College of Wisconsin and Mayo Clinic, followed by pediatric dermatology fellowship. Her clinical and academic interests include allergic contact dermatitis, atopic dermatitis, oral dermatology, hyperhidrosis, and pediatric skin conditions. She greatly enjoys teaching (and learning from!) the dermatology residents.


Outside of work she enjoys spending time with her husband and two young boys, watching sporting events, running, and going to concerts. 

Advisers and mentors

Department of Dermatology faculty members generally have an open-door policy. Daily interaction between staff and residents is encouraged. Upon graduation, most residents are able to name several staff members who strongly influenced their development and career choice.

To establish a framework for group mentoring and formalize the ongoing evaluation, however, each resident is assigned a faculty adviser upon entering the program. Advisers supply educational advice and personal support throughout the residency. Advisers also introduce residents and their families to Mayo Clinic and the city of Rochester.

Residents meet with their faculty advisers two to three times each year to assess progress, review feedback, set goals, and discuss research pursuits. Faculty advisers award residents their diplomas during the graduation ceremony. For some residents, the relationships established with faculty advisers continue throughout their careers.

Visiting professors

Many prominent professors visit Mayo Clinic each year. They present their work during lectures and participate in hospital rounds. Residents are encouraged to take full advantage of these opportunities.