Texas Medical and Surgical Associates offers the diagnosis and treatment of rheumatic diseases such as: rheumatoid arthritis, osteoarthritis, lupus, gout, ankylosing spondylitis, osteoporosis, vasculitis, inflammatory muscle disease, and many other connective tissue diseases.

Yijun Fan, MD

Dr Yijun Fan is a board certified rheumatologist and internist who has been caring for patients in Dallas for 20 years. He is a Fellow of the American College of Rheumatology and a member of the Texas and American Medical Associations. He earned his medical degree at Peking University Health Science Center in Beijing, China. He completed his residency in Internal Medicine at Nashville General Hospital and fellowship in Rheumatology at the University of Virginia. He is fluent in English and Mandarin. 
Dr Fan’s patients appreciate his unique blend of personal kindness and medical expertise. He has a special interest in immunology as the basis for inflammatory rheumatic disease and puts this knowledge into practice to diagnose and treat patients with autoimmune diseases such as Rheumatoid Arthritis, Psoriatic Arthritis, Ankylosing Spondylitis, Systemic Lupus Erythematosus, Dermatomyositis, and others.

Mary DeCardenas, PA-C

Mary DeCardenas has specialized in rheumatology since 2004 and has been practicing with Dr Fan since 2017. She completed the Physician Assistant Fellowship in Rheumatology at UT Southwestern Medical Center and the Dallas Veterans Affairs Medical Center. She is a Clinical Assistant Professor for the Department of Physician Assistant Studies at UT Southwestern where she earned a Master of Physician Assistant Studies in 2003. Mary is certified by the National Commission on Certification of Physician Assistants and licensed by the Texas Medical Board. 


Patients appreciate Mary’s thorough and empathetic approach to assessment of the whole person, whether addressing inflammatory and autoimmune disorders or chronic neurologic pain conditions. Prior to studying medicine, Mary earned an undergraduate degree in psychology at the University of Texas, held certification as a Massage Practitioner in California, and interned at the NASA Ames Research Center in support of biology research on the International Space Station.
M DeCardenas photo

Rheumatology Services

In House Knee Injections

Texas Medical & Surgical Associates offers in house knee injection treatments using Hyalgen, Eufexxa, Synvisc-One and many other medication options.

In House Infusion

Dr. Fan provides in house infusion using Remicade, Orencia, Symponi-Aria, Rituxan, Benlysta, Prolia, Enbrel, Humira, Cosentyvx, Cimzia, and more.

Specialized Treatment

TMSA offers individualized treatment for Lymes Disease, Psoriatic Arthritis, Rheumatiod Arthritis, Ankylosing Spondyloapathy, Auto Immuse Disorder, Immfalamtory Spondyloapathy and more.