Atypical Lyme Disease Rash With Negative Testing
A Lyme disease rash may not look like a bull’s-eye
Negative testing does not always exclude early Lyme disease
Recognition of atypical rashes may improve diagnosis and treatment
An atypical Lyme disease rash may appear very different from the classic bull’s-eye rash many clinicians expect. Khanna and colleagues described a 69-year-old woman who presented with an unusual rash despite testing negative according to CDC criteria. The case highlights how reliance on classic appearances or early testing alone may contribute to missed diagnoses.
In their study, “Atypical Lyme Disease Rash: A Case Report,” Khanna et al. describe a 69-year-old woman who tested negative for Lyme disease according to CDC criteria yet presented with findings concerning for Lyme disease after a tick bite.
According to the authors, the patient had only one positive Western blot band, which did not meet surveillance-based positivity criteria. This reinforces the limitations discussed in Lyme test accuracy, particularly early in illness.
Why atypical Lyme disease rashes are missed
Most clinicians recognize Lyme disease through the classic erythema migrans (EM) rash with central clearing. However, atypical Lyme disease rashes may appear uniformly red, blue-purple, itchy, bruised, or lack central clearing entirely.
In a Wisconsin study involving 69 patients from an endemic region, more than 50% of EM lesions were homogeneous in color and only 6% had the classic bull’s-eye appearance.
In West Virginia, 2021 data found that only 49% of reported Lyme disease cases had an erythema migrans rash.
Lyme disease rash: a unique appearance
The patient exhibited a rash without the classic outer ring or inner clearing often associated with EM rashes. She developed a purplish, itchy abdominal rash six days after a tick bite. Lesions were also present beneath both breasts, along with several smaller papules on the upper arm.
Patients with unusual rashes after exposure may also review warning signs described in bad signs after a tick bite.
The purple coloration was unusual. One study cited by the authors found that only 6% of EM rashes were purple.
Because rash presentations vary considerably, clinicians may compare findings with additional examples of erythema migrans rash pictures.
View rash images from the study.
Because atypical rashes may mimic bruising, cellulitis, fungal infections, or dermatitis, clinicians may also consider broader discussions around Lyme disease misdiagnosis.
Prior to Lyme testing, the patient was treated empirically with doxycycline for 14 days. One week later, there was significant improvement of the rash without additional symptoms.
Early recognition may improve outcomes and reduce progression toward persistent Lyme disease symptoms.
How often are atypical Lyme disease rashes recognized?
One study evaluating recognition of Lyme disease rash patterns found that clinicians frequently misidentified nonclassic presentations:
- 25.7% incorrectly identified uniformly red EM lesions
- 43.6% incorrectly identified disseminated EM lesions
- 33.0% incorrectly identified blue-purple EM presentations
These findings emphasize why clinicians may need to consider broader symptom patterns described in the Lyme disease symptoms guide, especially when testing is negative early.
The authors emphasized maintaining a high index of suspicion in patients with tick exposure, even when classic features are absent. Early recognition may help avoid delays described in delayed Lyme disease diagnosis.
Frequently Asked Questions
Can you have an atypical Lyme disease rash with negative testing?
Yes. Early Lyme disease testing may be negative, particularly when symptoms develop before a measurable antibody response.
What does an atypical Lyme disease rash look like?
Some atypical rashes appear uniformly red, purple, itchy, bruise-like, or lack the central clearing commonly associated with bull’s-eye lesions.
Can Lyme disease rashes be purple?
Yes. Purple or blue-purple presentations have been reported, although they appear less common than homogeneous red lesions.
Does everyone with Lyme disease develop a bull’s-eye rash?
No. Studies suggest many patients do not develop classic bull’s-eye lesions, and some may not develop noticeable rashes at all.
Should a tick bite with a strange rash be evaluated even if tests are negative?
Persistent or unusual rashes following tick exposure warrant medical evaluation, particularly when symptoms evolve or expand over time.
Clinical Takeaway
Atypical Lyme disease rashes may not resemble classic teaching images and may occur despite negative early testing.
Recognizing unusual rash patterns may reduce delayed diagnosis and improve opportunities for early treatment.
Related Articles
Explore additional resources on Lyme disease rashes and diagnosis:
A unique presentation of an EM rash
EM rash doesn’t always have bull’s-eye appearance
Lyme disease skin rash puzzles doctors, leads to misdiagnoses
Erythema migrans rash pictures
Bad signs after a tick bite
References
- Khanna S, Goebel LJ. Atypical Lyme Disease Rash: A Case Report. Cureus. 2024;16(2):e54779. doi:10.7759/cureus.54779.
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
