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Can syphilis cause rashes on the arms and legs as per the attached images?

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Posted on Tue, 22 May 2018
Question: My wife fears that she may have been exposed to syphilis about 5 years ago. In 2015, she had the RPR screen and FT-ABS screen and both came back as negative / non-reactive. Attached are some photos of rashes on her arms and legs that have developed within the last year. I also have some similar rashes, but mine are very itchy and hers are not. Neither of us experience any pain from these scars unless we scratch them. We've read that both the RPR and FT-ABS screens are susceptible to false negatives. Are there any other tests you can recommend that would give us assurance that we don't have syphilis?
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Answered by Dr. Olsi Taka (42 minutes later)
Brief Answer:
PCR test, but not necessary in my opinion.

Detailed Answer:
I read your question carefully and I understand your concern.

Since those tests are negative the only remaining test would be the PCR (polymerase chain reaction) test which searches for genetic material of the bacteria in the blood (or cerebrospinal fluid when neurological involvement is suspected).

However I wouldn't deem it that necessary. While it is true that both RPR and FT-ABS can produce false negatives that depends on the stage. Widespread skin lesions are manifested in secondary syphilis stage. In that stage sensitivity of RPR and FT-ABS is almost 100%. So it is very unlikely to get a negative result. Also usually those skin lesions appear 6 weeks to 6 months after exposure, so since they have appeared after 4 years it's unlikely to be due to syphilis.

I hope to have been of help.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Dr. Olsi Taka

Neurologist

Practicing since :2004

Answered : 3659 Questions

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Can syphilis cause rashes on the arms and legs as per the attached images?

Brief Answer: PCR test, but not necessary in my opinion. Detailed Answer: I read your question carefully and I understand your concern. Since those tests are negative the only remaining test would be the PCR (polymerase chain reaction) test which searches for genetic material of the bacteria in the blood (or cerebrospinal fluid when neurological involvement is suspected). However I wouldn't deem it that necessary. While it is true that both RPR and FT-ABS can produce false negatives that depends on the stage. Widespread skin lesions are manifested in secondary syphilis stage. In that stage sensitivity of RPR and FT-ABS is almost 100%. So it is very unlikely to get a negative result. Also usually those skin lesions appear 6 weeks to 6 months after exposure, so since they have appeared after 4 years it's unlikely to be due to syphilis. I hope to have been of help.