Lyme Disease Mimics Dermatomyositis and Autoimmune Disease

Lyme disease can resemble autoimmune illness.
Dermatomyositis-like symptoms may occur in some patients.
This case highlights the risk of misdiagnosis and delayed treatment.

Lyme disease can mimic autoimmune diseases such as dermatomyositis—leading to potential misdiagnosis and delayed treatment.

The clinical presentation was consistent with dermatomyositis (DM), an autoimmune inflammatory muscle disease.

“A 76-year-old female presented with fatigue, malaise, weight loss and progressive proximal muscle weakness after a flare-up of shoulder arthritis,” writes Novitch, a medical student at the Medical College of Wisconsin.

Dermatomyositis-Like Presentation

The physical findings were consistent with DM. “She had a heliotrope rash and a ‘Shawl sign,’ in addition to generalized cutaneous erythema with edema,” writes Novitch.

A heliotrope rash is a violet or bluish-purple rash that develops on areas of the skin.

“A widely distributed erythema of the upper neck, extending to the upper back and upper shoulders indicating a ‘Shawl sign’ was noted,” Novitch states.

Dermatomyositis is an autoimmune inflammatory muscle disease that can cause muscle weakness and characteristic skin findings.

Clinical Deterioration and Diagnostic Clues

The doctors prescribed antibiotics for Lyme disease (LD) based on clinical judgment.

The woman was prescribed an empiric dose of IV Rocephin but began to deteriorate. “The patient appeared toxic, became hypotensive and developed high-grade fever,” writes Novitch.

She was transferred to the intensive care unit (ICU) for close monitoring.

The doctors’ clinical judgment of Lyme disease proved to be correct.

“While in ICU, two target-shaped lesions were noted on her left scapula, highly suggestive of LD-related EM; they were not previously reported or observed,” writes Novitch.

Follow-up serologic tests confirmed the diagnosis of Lyme disease.

Treatment and Recovery Without Immunosuppression

The patient recovered with a combination of 5 days of IV doxycycline combined with 5 days of IV Rocephin followed by two weeks of oral doxycycline.

“Her DM-like presentation showed an effective response to antimicrobial treatment, and therefore, required no steroids or immunosuppressants,” writes Novitch.

This outcome supports an infectious rather than autoimmune etiology.

Why Lyme Disease Can Mimic Autoimmune Disease

Lyme disease is known as a clinical “great imitator.” It can resemble autoimmune, neurologic, and rheumatologic conditions.

Failure to recognize this overlap may lead to inappropriate treatment with immunosuppressive medications.

Novitch and colleagues point out that “LD could be a great mimicker of other autoimmune diseases like DM.”

Frequently Asked Questions

Can Lyme disease mimic autoimmune disease?

Yes. Lyme disease can resemble autoimmune, neurologic, and rheumatologic illnesses, including dermatomyositis.

Can Lyme disease cause dermatomyositis-like symptoms?

Some patients with Lyme disease may develop muscle weakness, rash, fatigue, and inflammatory findings that resemble dermatomyositis.

Why is Lyme disease called the great imitator?

Lyme disease may mimic autoimmune disorders, neurologic illness, chronic fatigue, arthritis, and other inflammatory conditions.

Clinical Takeaway

Lyme disease can mimic autoimmune disorders like dermatomyositis. Consider tick-borne infection before initiating immunosuppressive therapy—especially in endemic regions.

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Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention