Test and evaluate a new diagnostic method (SRM-MS/MS: Selected Reaction Monitoring- Mass spectrometry) for Lyme Borreliosis on human skin biopsies. Patients included are those with the early skin manifestation (erythema migrans).

This new proteomic method will be compared to the two existing method: culture of Borrelia and PCR detection of Borrelia (DNA detection of the bacteria).

Inclusion Criteria:

• Erythema migrant as criteria EUCALB or atypical form associated to tick's sting
• Patient having signed a consent
• Patient affiliated to a social security scheme

Exclusion Criteria:

• Prior treatment with antibiotics
• Erythema migrans on the face
• Bleeding disorders
• Anticoagulant treatment
• Inability to give clear information (subject in an emergency situation, understanding of the topic difficulty, ...)