Can Skin Biopsy Diagnose Lyme Disease?

I noticed a quarter sized red rash with what looked like a central bite mark. It was on my upper arm, but I do not remember being bitten by anything.

After 10 days it was still there and developed a large (several inches) white space around it. I could not get this white area to change color, even with rubbing. I went to a dermatologist who said a skin biopsy was necessary to rule out a tick bite.

When the results came back, he said it showed a bite from an "arthopod" but it did not show it was erythmia migrans, so it was not lyme disease.

However, "arthopod" could still mean tick right? So can they 100% for sure know that I am not infected with lyme disease? Shouldn't they do a lab test also?

[Dr Santos]

Hi,

Lyme disease is the most common tick-borne disease which presents initially as circular, outwardly expanding rash called erythema  migrans which occurs at the site of the tick bite 3 to 32 days after being bitten.The borrelia bacteria may then spread through the bloodstream and  may develop at sites across the body that bear no relation to the original tick bite.

Because it is very difficult culturing Borrelia bacteria in the laboratory, diagnosis of Lyme disease is typically based on the clinical exam findings, a history of exposure to endemic Lyme areas, as well as serological tests. Most recommended tests are blood tests that measure antibodies made in response to the infection. However, these tests may not be reliable in patients with early disease, but they are quite reliable for diagnosing later stages of disease. It would be best to discuss this with your doctor to alleviate anxiety in your part. This link may be helpful:  http://en.wikipedia.org/wiki/Lyme_disease
Take care and keep us posted.

[upbeat633]

Thank you for your response doctor. Could you please answer one more question?

I have now had the rash for 3 weeks. It is not spreading nor itchy, but it does seem deeper in color, now appearing almost purple even with daily application of desonate (?) a mild corticosteroid.

Is three weeks too early for serological testing to show infection/antibodies?

I live in Oregon but noticed the rash on my arm one day after returning from 3 days in Cleveland. I thought I was bitten on the leg by something in Cleveland, but did not see anything and nothing has developed on my leg.  I do not believe either geographic region is high for lyme disease, but I would like to definitely rule it out.