Our Practice

We provide the best dermatologic care, employing the latest scientific and pharmacologic technologies.

The San Luis Dermatology and Laser Clinic has been serving the San Luis Obispo area in the person of Dr. Jeffrey Herten since October, 1977. From a one doctor, one nurse, one front office person practice in an 800 square foot office, the clinic has grown into a four physician with a physician assistant and twenty support staff now practicing in two locations in San Luis Obispo.

The clinic offers the latest in diagnostic and therapeutic clinical dermatology, expert cancer diagnosis and surgery including Mohs Micrographic Surgery, dermatoscopic evaluation and digital photography on atypical moles leading to the early diagnosis and treatment of melanoma, and a stable of the finest lasers in use in laser surgery today. All these technologically advanced services are provided by caring health care professionals assisted by friendly and efficient nurses, medical assistants, and support staff. In addition, Dr. Herten’s faculty teaching appointment at U.C. Irvine provides an unlimited network of academic physicians to whom difficult and complex dermatologic problems can be referred for consultation.

R. Jeffrey Herten, M.D.​, FAAD

Diplomate of the American Boards of Dermatology and Dermatopatholgy. Dr. Jeffrey Herten has 35 years of experience in the practice of Dermatology, Dermatologic Surgery, Mohs Micrographic Surgery, and Dermatopathology.



  • University of Southern California. B.A., Anthropology. June 1968. Cum Laude.
  • Medical School: University of California, Irvine, M.D., June 1972. Regent Scholar.


  • Internship: Los Angeles County-U.S.C. Medical Center, Los Angeles, California. 1972-73.
  • Residency: Combined Dermatology Program, University of California, Irvine. 1973-76.
  • Fellowship: Fellowship in Dermatopathology, Combined Dermatology Program, University of California, Irvine. 1976-77

Board Certification

  • Diplomate of the American Board of Dermatology – 1977
  • Diplomate of the American Board of Dermatopathology – 1978

Memberships, Honors, and Awards


  • Member of Blue Key Honor Society, University of Southern California. 1967-68
  • Member of Skull and Dagger, Senior Men’s Honor Service Organization. University of Southern California. 1967-68
  • Member of Trojan Knights, Junior-Senior Men’s Service Organization. University of Southern California. 1966-68
  • Academic Scholarship, University of Southern California. 1964-68
  • Regents’ Scholarship, University of California, Irvine, California College of Medicine. 1970-72
  • Chief Resident, Combined Dermatology Program, University of California, Irvine. 1975-76
  • Fellow of the American Academy of Dermatology. 1977- Present
  • Fellow of the American Academy of Dermatopathology. 1979-Present
  • Fellow of the American Society of Dermatologic Surgery. 1981-Present
  • Member of the Tri-County Dermatologic Society. 1983-Present
  • Treasurer, Tri-County Dermatologic Society. 1990-92
  • President, Tri-County Dermatologic Society. 1992-93
  • Dermatopathology Teacher of the Year, University of California, Irvine. 1999-2000
  • Dermatology Teacher of the Year, University of California, Irvine. 2003-2004
  • Dermatology Teacher of the Year, University of California, Irvine, 2007-2008

Medical Licensure

California A25307. 1973

Teaching Positions

  • Clinical Associate in Medicine, Dermatology, University of California, Irvine. 1975-76
  • Visiting Lecturer in Venereal Disease, California State University, Long Beach. 1975-76
  • Clinical Instructor in Medicine, Dermatology, University of California, Irvine. 1976-78
  • Assistant Clinical Professor of Dermatology. University of California, Irvine. 1978-1986
  • Associate Clinical Professor of Dermatology and Dermatopathology, University of California, Irvine. 1986-Present
  • Visiting Lecturer on the Biology of Skin Cancer, California Polytechnic State University, San Luis Obispo. 1980-1999
  • Clinical Staff, Beckman Laser Lab and Medical Clinic, University of California, irvine. 1996-2001

Scientific Publications

  1. Herten, R. Jeffrey, Acanthosis Nigricans, Continuing Medical Education. March 1977
  2. Herten, R. Jeffrey, Polymorphous Malignant Lymphoma with Lymphocytic Infiltrative Pneumonia, Archives of Dermatology. December 1976
  3. Barr, R.J., Herten, R.J., Rapid Hemotoxylin-Eosin Method for Tzanck Preparations from Viral Vesicles, Journal of the American Medical Association. March 1977
  4. Barr, R.J., Herten, R.J., Multiple Premalignant Fibroepitheliomas of Pinkus: Case Report and Review of the Literature, Cutis. March 1978
  5. Barr, R.J., Herten, R.J., and Graham, J.H., Synovial Sarcoma Metastatic to Skin: A Histochemical and Ultrastructural Study, Archives of Dermatology. December 1976
  6. Stone, O.J., Barr, R.J., and Herten, R.J., The Nail Biopsy. Cutis, September 1977
  7. Herten, R.J., Non-scarring Hair Loss Disorders, Post-Graduate Medicine, October 1982
  8. Herten, R.J., Seborrheic Keratoses (including the Sign of Leser-Trelat), Stucco Keratoses, Hyperkeratoiss Lenticularis Perstans (Flegel), and Benign Lichenoid Keratoses, Chapter in Co-operative Textbook on Geriatic Dermatology: Clinical Diagnosis and Practical Therapy, edited by Victor Newcomer, M.D. and Edward M. Young, Jr., M.D. Published by Igaku-Shoin Medical Publishers Inc., New York. 1989
  9. Herten, R.J. Chemical and Mineral Deposition in the Skin, Chapter in Co-operative Textbook of Dermatopathology, Edited by Evan Farmer, M.D., Appleton-Century-Crofts Publishers, New York. 1989

Other Publications

  1. The Western States 100: A Participant’s View. Journal of the American Medical Athletic Association. January 1985
  2. Hey, Mister, Wanna Buy a Horse? Journal of the Ride and Tie Association. October 1987
  3. Send the Best. Endurance News. February 1992
  4. The Yanks are Coming. Endurance News. March 1992
  5. A Way of Life. Endurance News. April 1992
  6. From the Front. Endurance News. May 1992
  7. Check These Out. Endurance News. June 1992
  8. Fools and Ride and Tiers. Journal of the Ride and Tie Association. July 1992
  9. Riding for America. Endurance News. July 1992
  10. Riding for America II. Endurance News. August 1992
  11. In Pursuit of Lauren: The 1992 Championship Ride & Tie. Trailblazer. January 1993
  12. A Sight for Sore Thighs: The 1993 Championship Ride & Tie. Trailblazer. January 1994
  13. High Stakes Ride & Tie. Trailblazer. April 1994
  14. Carpe Vitam: The Amazing John Melville. Trailblazer. May 1994
  15. A Buckle at Last: The 1993 Tevis Cup Ride. Trailblazer. January 1994
  16. A Horse Person’s Guide to Sun Protection. Ride Magazine. April 1995
  17. To Finish is to Survive: The 1995 Ride & Tie Championship. Trailblazer. March 1996

Advisory Work & Other Interests


  • Autologous Skin Grafting for Vitiligo. Research advisor for Senior Project with James Thurlow. 1996
  • Lyme Disease in San Luis Obispo County. Research advisor for Senior Project with Jim Nunle. 1996
  • Ultraviolet in the 90s. Pilot project for public education including broadcast and publication of minimum daily cancer dose of ultraviolet, user guide to sunscreens, ozone update, and tanning salon hazard awareness. Research advisor for Senior Project with Tom Waddington. 1996


  • Long distance running. Running for fitness since 1970, logging over 40,000 miles in training.
  • Veteran of forty-three marathons, fourteen fifty mile runs, and three 100 mile, one-day runs.
  • Endurance horseback riding. Riding since 1986 with 5,000 miles in competition, including a 14th place finish in the famous Tevis Cup 100 mile horse race.
  • Ride and Tie Competition. Active since 1986. Competed in twenty-one Ride and Ties, including nine World Championship Events. Winner of Man-Woman World Championship in 1992.
  • California State Parks Volunteer, Coast Mounted Assistance, Montana de Oro State Park. 1998-Present.
    • Trail maintenance. Committee Chairman and work party organizer. 1996-98.
    • President 1998-99, 1999-2000, 2000-2001
  • Medical Director, Liberty Tattoo Removal Clinic, San Luis Obispo County. September 2000-2005. This is a volunteer clinic to remove anti-social tattoos from parolees, former gang members, and others in order that they can re-enter society, be employed, etc.
  • Board of Governers, Western States Trail Ride, 2003-present
  • Chairman, Western States Trail Endowment Foundation. 2009

Michael P. Heffernan, M.D., FAAD ​

Dr. Heffernan grew up in small town coastal New Hampshire. He was the first person in his family to attend college. He received his undergraduate degree from the University of Notre Dame, his medical degree from the University of Michigan, and trained in Dermatology at Stanford where he was chosen to be chief resident.

Dr. Heffernan then served our country in the Air Force. After returning from service, he taught at Washington University and Wright State University where he also served as Chairman of the Department of Dermatology and Residency Program Director. Dr. Heffernan’s research has lead to the development of dozens of medications. He recently served as a Distinguished Medical Fellow and Senior Medical Director at Eli Lilly & Co.

Dr. Heffernan is an internationally recognized dermatologist for problems ranging from the common to the complex. He specializes in the management of skin cancer and pre-skin cancers. He also specializes in the management of all complicated dermatologic disorders including psoriasis, lichen planus, mycosis fungoides, vasculitis, and pemphigus.

Dr. Heffernan is blessed with a great wife and 4 rambunctious daughters who are looking forward to establishing deep roots in San Luis Obispo.

Charles B. Fishman, M.D.

Dr. Fishman graduated from Indiana University School of Medicine in 1968. He interned and took one extra year of Internal Medicine residency at Wadsworth-VA-UCLA Hospital in 1968-70.

After two years as a doctor in the U.S. Army, he completed his residency training in Dermatology at the University Of Colorado School Of Medicine in Denver in 1975.

He was board certified by the American Board of Dermatology in 1975 and by the American Board of Pathology in 1977 for special competence in Dermatopathology.

He started practice in San Luis Obispo at the French Clinic in 1975 and has been in his own private practice since 1980.

He founded the California Central Coast Dermatological Society in 1976 and remains as its president. The society meets monthly to present patients and at a separate meeting to discuss the latest in dermatological literature. He is a member of numerous dermatological educational societies including the American Academy of Dermatology, American Society of Dermatologic Surgery, Tri-County Dermatologic Society, and California Medical Association.

He cares for all diseases of the skin, hair, and nails, and his main interests and expertise are in diagnosis and treatment of skin cancer, rashes such as psoriasis and eczema, and in evaluation of cosmetic concerns.

He has certificates in the use of lasers, BOTOX®, and fillers such as Restylane® and RADIESSE®. He is also proficient in the use of chemical peels and has done sclerotherapy for spider veins of the legs for more than 25 years.

Joseph Diehl, M.D., FACMS, FAAD

Dr. Diehl was born and raised in San Luis Obispo, and graduated from San Luis Obispo High School. He received his undergraduate degree from the University of California San Diego, his medical degree from UCLA, did an internship in Internal Medicine at UCLA-Olive View Medical Center, and trained in Dermatology at UCLA. He then stayed on as a full-time faculty member teaching at UCLA. Dr. Diehl is board certified by the American Board of Dermatology (ABD), and a Fellow of the American Academy of Dermatology (AAD).

Dr. Diehl also completed an intensive fellowship through the American College of Mohs Surgery in Mohs Micrographic Surgery and Dermatologic Oncology under the tutelage of internationally known Dr. David Kent at Dermatologic Surgery Specialists in Macon, GA, a referral center for the most difficult and recurrent cases in Middle and Southern Georgia. There he completed over 1,500 surgeries, with additional training in laser and cosmetic dermatology. He has published dozens of articles and spoken around the country on subjects including Mohs micrographic surgery, laser surgery, and medical dermatology.

Dr. Diehl specializes in the management of complex and routine skin cancers, Mohs micrographic surgery, surgical dermatology, and general dermatology.

He is excited to be returning home to his roots on the Central Coast and the year-round surfing, golf, tennis and many outdoor activities that make up the SLO Life.


Cheryl Ketelsen, Diplomate Fellow, SDPA

Cheryl Ketelsen received her undergraduate degree in Kinesiology from San Diego State University and graduated cum laude. She obtained her Masters degree in physician assistant studies from Samuel Merritt University in Oakland CA. in 2015. Prior to specializing in dermatology she spent her first year working both primary care and urgent care here in San Luis Obispo. She has currently been practicing general dermatology since 2017.

When she is not in clinic she enjoys both international and domestic travel, learning about different cultures, hiking, snowboarding, water sports, and spending time with her friends and family.