There are 3 main skin manifestations associated with Lyme disease. A publication Cutaneous Lyme borreliosis: Guideline of the German Dermatology Society has some excellent images and discussions of the variability and differential diagnosis of Lyme disease skin manifestations.
The Erythema migrans (EM) of Lyme disease can take many forms. The best known is a roughly circular red rash, without itching or pain, that slowly spreads outwards. It may clear in the middle and is often called a bull’s eye rash.
- The rash does not have to be circular
- The rash can become very large (40cm across) with diffuse edges
- There can be many rashes, not just one
- The rash is not necessarily at the site of the tick bite
- In UK studies around 1 in 3 of people did not see a rash, but the number who notice it may increase with increased publicity and awareness.
Immediately after an attached tick has been removed from the skin, the site of the bite will continue to be a little red, perhaps for a few days – this is not in itself an indication of Lyme disease. The EM usually develops about 14 days after the bite, but it can be sooner or later.
Acrodermatitis Chronica Atrophicans (ACA)
This is an uncommon, bluish-red discolouration and swelling, on the surfaces of legs and arms, that develops several years after infection. It takes a chronically progressive course and finally leads to a widespread atrophy of the skin in the area which has been described as “cigarette paper- like wrinkling of the skin”.
There is often associated peripheral neuropathy.
This is uncommon in Europe, and extremely rare in the US. It is a bluish-red, solitary swelling, with a diameter of up to a few centimetres, most often seen on ear lobes or nipples.
- Hofmann et al 2017 Cutaneous Lyme borreliosis: Guideline of the German Dermatology Society GMS German Medical Science 2017,Vol.15, ISSN1612-3174