At a Glance - Erythema annulare centrifugum versus Lyme disease

Contributed by Dr Jean Watkins, a retired GP in Hampshire

Erythema annulare centrifugum: polycyclic plaques
Erythema annulare centrifugum: polycyclic plaques

Erythema annulare centrifugum

Aetiology
Associated with:

  • Bacterial infections: Escherichia coli, streptococcus or mycobacteria.
  • Fungal infections: dermatophytes, candida or pityrosporum.
  • Lice or roundworm.
  • Viral infections.
  • Drugs: estrogens, cimetidine, penicillin, salicylates, antimalarials, amitriptyline.
  • Blue cheese and tomatoes.
  • Malignancy.
  • Liver disease, sarcoidosis.

Presentation

  • Can occur at any age.
  • Rash usually occurs on the lower limbs. Initially one or more erythematous papules.
  • Lesions grow into annular, polycyclic plaques that spread outwards, clearing at centre, often with a rim of scale. Asymptomatic or itching.

Investigations

  • Skin scraping to exclude fungal infection. Skin biopsy.
  • FBC and LFTs will indicate infection and liver problems.
  • ELISA and western blot tests to exclude Lyme disease.
  • ANA test to exclude systemic lupus erythematosus.
  • Stool specimen if parasitic worms suspected.
  • Chest X-ray might indicate TB, sarcoidosis or lymphoma.

Management

  • Usually self-limiting, clearing in weeks, but may last for years.
  • No other treatment required but topical steroids help itching and inflammation.

Lyme disease

Lyme disease: remove the tick

Aetiology

  • The bacterium Borrelia burgdorferi borne by infected ticks, often carried by deer.
  • Infection may remain localised or disseminate around body.

Presentation

  • Localised disease: seven to 10 days after initial tick bite, erythema migrans develops and lymph glands enlarge.
  • Annular erythematous patch, up to about 7cm in diameter, sometimes with central clearing or purpura.
  • Disseminated Lyme disease: multiple patches of erythema migrans. Causes headache, fever, paraesthesia, facial paralysis, lymphadenopathy.
  • Late Lyme disease causes arthritis, confusion, vertigo, increasing paraesthesia.

Investigations

  • Diagnosis possible on history of tick bite, erythema migrans and increasing symptoms.
  • Blood tests may become positive after one month.

Management

  • Early treatment shortens duration.
  • Remove ticks immediately and seek advice early.
  • Doxycycline 200mg (72 hours after bite).
  • For late complications try 30 days of doxycycline. Can also use amoxicillin, cefuroxime or azithromycin. IV antibiotics can be used in severe cases.
  • Prevention (long trousers, insect repellents and so on).

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Register

Already registered?

Sign in

Follow Us:

Just published

BMA GP chair: 'GPs let down by tone deaf NHS demands on face-to-face appointments'

BMA GP chair: 'GPs let down by tone deaf NHS demands on face-to-face appointments'

NHS England has let down general practice with its 'tone deaf' demand for all patients...

GPs told to offer face-to-face appointments for all patients

GPs told to offer face-to-face appointments for all patients

GPs have condemned a 'blanket' demand from NHS England that all patients should be...

GP federation network seeks to boost primary care representation amid NHS reforms

GP federation network seeks to boost primary care representation amid NHS reforms

The NHS Confederation has set up a national network for GP federations in a bid to...

Sharp rise in GPs seeking mental health support during past year

Sharp rise in GPs seeking mental health support during past year

The number of GPs seeking help from NHS Practitioner Health, the specialist service...

Podcast: The GP workload crisis, mental wellbeing and vaccination success

Podcast: The GP workload crisis, mental wellbeing and vaccination success

In this episode of our new podcast Talking General Practice we look at the GP workload...

Long wait for COVID-19 public inquiry 'could drive doctors to quit NHS'

Long wait for COVID-19 public inquiry 'could drive doctors to quit NHS'

Doctors' leaders have criticised government plans to delay a public inquiry into...