Lyme disease misdiagnosed as psoriatic arthritis


In their article, “Rare case of Lyme borreliosis in a patient presenting with dactylitis and skin rash,” Steppat et al. describe a patient with Lyme borreliosis, who was initially misdiagnosed with Psoriatic arthritis (PsA), a chronic inflammatory disease that occurs when your immune system mistakenly attacks healthy joints and skin. [1]


The man, in his 70’s, presented with dactylitis (severe swelling of the fingers or toes), onycholysis of the nails (nail separates from the skin) and scalp psoriasis, which lead to the diagnosis of psoriatic arthritis.

However, he did not respond to treatment with corticosteroids or disease-modifying antirheumatic drugs.

“A skin biopsy was performed showing histopathological changes compatible with Lyme borreliosis (LB) and serum contained IgG antibodies against Borrelia burgdorferi,” wrote Steppat and colleagues.

“To our knowledge, this is the first case of LB describing asymmetrical dactylitis in a hand.”

The man did not recall a tick bite but reported that his fingers first began to swell several weeks after gardening.

“It was concluded that the patient was not suffering from PsA but [Lyme borreliosis] with manifestations of dactylitis, arthritis and [acrodermatitis chronica atrophicans] ACA,” the authors wrote.

After 1 week of penicillin, the swelling of the patient’s fingers improved.

After 6 months, the arthritis, tenosynovitis (inflammation of the tendon sheath), soft tissue swelling and skin rash had completely resolved.

“… dactylitis is a common feature of [psoriatic arthritis]. However, dactylitis may also be seen as a clinical feature in several other diseases such as [Lyme borreliosis].”

Furthermore, the authors point out, that Lyme borreliosis can occur even when there is no history of a tick bite or erythema migrans rash.

When a patient is not responding to treatment for psoriatic arthritis, it is “crucial to re-evaluate the medical history, objective examinations and laboratory tests. In this case, the conclusive clue was hidden in the skin biopsy.”


  1. Steppat A, Skaarup Andersen N, Andreasen CMRare case of Lyme borreliosis in a patient presenting with dactylitis and skin rashBMJ Case Reports CP 2023;16:e253182.

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4 months ago

I suffered with swollen hands, painful fingers. I finally started seeing a rheumatologist group. With xrays they determined I had wear and tear and said my blood didn’t carry the markers for RA but I had high inflammation and treated me for psoriatic arthritis. I took some pretty serious medicines for years. When they suggested I start using Humera, I quit seeing them. I had two friends who had developed Lymphoma. Twenty years forward in 2020 I became very sick, high fever, vomiting, chills, body aches. This was during COVID which really scared me. I also got these big round rashes all over my trunk and arms and legs. Two weeks after and the rash hadn’t gone away I went to a walk-in and being in Maine at the time, the PA took one look at me, asked me where I hurt that was new and immediately told me I had Lymes She told me that she was prescribing 3 weeks of Doxycycline and said I’m not even going to test you yet because the tests show false negatives because it doesn’t show up for a while. I took the 3 weeks of Doxy and my wife and I started the research. Learning that sometimes more treatment is required. We found a practitioner in Maine who had been misdiagnosed as having MS when in fact it was Lymes. With the IGENIX testing it revealed I had a past infection in my life and that a new tick bite made me really sick. I had four co-infections. Its now 2023 and I’m still being treated. I lost all feeling in my legs, feet, hands. I was in bed for at least 8 months. I’ve had lots of antibiotic therapy including a pic line, Cefroxin, I’ve had neck surgery from a bad fall as my legs were getting weaker, I’ve had lots of rehab. LDN, special tinctures made by a naturalist in Maine Its been so hard being in Florida where Lymes is never a consideration. I finally was able to convince my cardiologist to give me a pacemaker and eblation. I have had A-fib in my past and had two conversions. The 2nd conversion after open heart surgery replacing two valves and a cabbage bypass. When I got so sick in 2020 and with the very high fever my blood pressure dropped so low. Remember COVID was in its first stages.… Read more »

Mary Britton
Mary Britton
4 months ago

As one who possibly suffers from this I am encouraged that you spread the knowledge and educate on this easily mis diagnosed disease. Thank you.

David R Thomas
4 months ago

As a Lyme literate Advocate. This is a very good share as I have read about this for years and watched a golfer suffer and treat by big pharma drugs purposely for arthritis instead of Lyme.