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Multisystem infection caused by Borrelia burgdorferi (a spirochete) transmitted via Ixodes ticks.

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https://www.youtube.com/watch?v=viP5Ta0K-ho

https://www.youtube.com/watch?v=4MIFeNTfZ1E

Etiopathogenesis

Pathology:

Untitled

Clinical Features

Stage Timeline Presentation
Early localized Days–weeks • Erythema migrans (expanding annular rash, “bull’s-eye”).
• Flu-like symptoms.
Early disseminated Weeks–months • Multiple erythema migrans.
• Neurologic: meningitis, cranial neuropathy (esp. bilateral facial nerve palsy), radiculoneuritis.
• Cardiac: myocarditis, AV block.
• Migratory polyarthritis.
Late Months–years • Chronic arthritis (esp. knee).
• Encephalopathy, peripheral neuropathy, chronic fatigue.
• Acrodermatitis chronica atrophicans (skin).

Clinical manifestations of Lyme borreliosis: Lyme borreliosis is categorized into early localized, early disseminated and late stages, although manifestations can overlap. The infection starts at the tick bite site, presenting as an erythema migrans skin lesion. From the initial skin site, Lyme borreliae can disseminate to other skin and extracutaneous sites within days to weeks. Borrelial lymphocytoma is an uncommon, early localized manifestation most often observed in children that appears as a single bluish-red nodule usually on the earlobe. Early disseminated manifestations include multiple erythema migrans skin lesions, early Lyme neuroborreliosis and Lyme carditis, usually occurring within 1–2 months after infection. Multiple erythema migrans skin lesions resemble the initial primary lesion but are usually smaller in size and do not have a punctum (because a punctum only occurs at the tick bite site). Early Lyme neuroborreliosis typically presents with cranial neuropathy (especially peripheral facial nerve palsy), lymphocytic meningitis and/or painful radiculopathy. Lyme carditis most commonly presents with fluctuating acute atrioventricular block. Late-stage manifestations occur months after the initial infection. Lyme arthritis is the most common late manifestation in the USA. Lyme arthritis presents with intermittent or persistent joint swelling and pain affecting large joints, particularly the knee. Acrodermatitis chronica atrophicans, the most common late manifestation in Europe, is characterized by reddish-blue discoloration and swelling of the skin, usually on the distal parts of the extremities, that slowly expand and progress to an atrophic stage. Borrelial lymphocytoma and acrodermatitis chronica atrophicans are manifestations of Lyme borreliosis that only occur in Europe. Late Lyme neuroborreliosis presenting with encephalitis, myelitis or encephalomyelitis has been reported in Europe but is very rare in the USA.

Clinical manifestations of Lyme borreliosis: Lyme borreliosis is categorized into early localized, early disseminated and late stages, although manifestations can overlap. The infection starts at the tick bite site, presenting as an erythema migrans skin lesion. From the initial skin site, Lyme borreliae can disseminate to other skin and extracutaneous sites within days to weeks. Borrelial lymphocytoma is an uncommon, early localized manifestation most often observed in children that appears as a single bluish-red nodule usually on the earlobe. Early disseminated manifestations include multiple erythema migrans skin lesions, early Lyme neuroborreliosis and Lyme carditis, usually occurring within 1–2 months after infection. Multiple erythema migrans skin lesions resemble the initial primary lesion but are usually smaller in size and do not have a punctum (because a punctum only occurs at the tick bite site). Early Lyme neuroborreliosis typically presents with cranial neuropathy (especially peripheral facial nerve palsy), lymphocytic meningitis and/or painful radiculopathy. Lyme carditis most commonly presents with fluctuating acute atrioventricular block. Late-stage manifestations occur months after the initial infection. Lyme arthritis is the most common late manifestation in the USA. Lyme arthritis presents with intermittent or persistent joint swelling and pain affecting large joints, particularly the knee. Acrodermatitis chronica atrophicans, the most common late manifestation in Europe, is characterized by reddish-blue discoloration and swelling of the skin, usually on the distal parts of the extremities, that slowly expand and progress to an atrophic stage. Borrelial lymphocytoma and acrodermatitis chronica atrophicans are manifestations of Lyme borreliosis that only occur in Europe. Late Lyme neuroborreliosis presenting with encephalitis, myelitis or encephalomyelitis has been reported in Europe but is very rare in the USA.

![Solitary erythema migrans skin lesions in patients in the USA (parts a and b) and Europe (parts f and g). Erythema migrans lesion in a patient from the Caribbean who acquired the infection in Westchester County, New York, USA (part c). Multiple erythema migrans in patients in the USA (parts d and e). Borrelial lymphocytoma on the ear helix (part h), acrodermatitis chronica atrophicans on the dorsal side of the right hand (part i).

Part c from Nadelman, R. B. Erythema migrans. Infect. Dis. Clin. North Am. 29, 211–239 (2015). Strle, F., Strle, K., Marques, A. et al. Lyme borreliosis. Nat Rev Dis Primers 12, 15 (2026). https://doi.org/10.1038/s41572-026-00691-0](attachment:8e1fd30b-b69d-4d11-85d7-96e7f5036130:41572_2026_691_Fig7_HTML.webp)

Solitary erythema migrans skin lesions in patients in the USA (parts a and b) and Europe (parts f and g). Erythema migrans lesion in a patient from the Caribbean who acquired the infection in Westchester County, New York, USA (part c). Multiple erythema migrans in patients in the USA (parts d and e). Borrelial lymphocytoma on the ear helix (part h), acrodermatitis chronica atrophicans on the dorsal side of the right hand (part i).

Part c from Nadelman, R. B. Erythema migrans. Infect. Dis. Clin. North Am. 29, 211–239 (2015). Strle, F., Strle, K., Marques, A. et al. Lyme borreliosis. Nat Rev Dis Primers 12, 15 (2026). https://doi.org/10.1038/s41572-026-00691-0

Radiology