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Mycoplasma exanthem in Adult
Other Resources UpToDate PubMed

Mycoplasma exanthem in Adult

Contributors: Haya Raef MD, Susan Burgin MD
Other Resources UpToDate PubMed


Mycoplasma exanthem is caused by the organism Mycoplasma pneumoniae, which is not a true bacterium, as it lacks a cell wall. It is among the most common causes of atypical pneumonia in children and young adults. Its long incubation period may be responsible for the slowly evolving epidemics seen in young people, military barracks, schools, and families. Rashes frequently occur and can be a diagnostic clue. The incidence of exanthems in association with M pneumoniae has been reported to be between 10% and 35%.

Patients usually have a slowly evolving illness with eventual headache, low-grade fever, malaise, myalgias, dry cough, sore throat, and fatigue. Coughing can be severe and with uncontrolled paroxysms. The disease otherwise tends to be mild and is often self-limited. Symptoms typically last 1-2 weeks followed by gradual resolution of the cough and fatigue.

Skin manifestations typically include erythematous maculopapular and vesicular lesions, distributed on the trunk, arms, and legs. Bullous, petechial, and urticarial lesions have also been reported in the literature. Exanthems are often mild and self-limiting. They may or may not be accompanied by pruritus and can persist for 2 weeks.

Rare complications include hepatitis, meningitis, pericarditis, arthritis, and acute hemolytic anemia. In a few patients, pneumonia can lead to adult respiratory distress syndrome.

Related topics: Mycoplasma pneumonia, reactive infectious mucocutaneous eruption (RIME)


A49.3 – Mycoplasma infection, unspecified site

406595002 – Infection due to Mycoplasma pneumoniae

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Differential Diagnosis & Pitfalls

  • Mononucleosis
  • Viral exanthem
  • Reactive infectious mucocutaneous eruption (RIME) – Also caused by M pneumoniae, and by other infectious agents; a prominent mucositis that usually affects 2 or more mucosal sites is accompanied by a sparse acral eruption.
  • COVID-19
  • Urticaria
  • Juvenile idiopathic arthritis
  • Exanthematous drug eruption
  • Erythema marginatum

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Last Reviewed:07/18/2021
Last Updated:02/27/2022
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Mycoplasma exanthem in Adult
A medical illustration showing key findings of Mycoplasma exanthem : Fatigue, Erythema, Widespread distribution, Pharyngitis, Dry cough, Maculopapular rash
Clinical image of Mycoplasma exanthem - imageId=47705. Click to open in gallery.  caption: 'Excoriated and crusted pink plaques on the flank.'
Excoriated and crusted pink plaques on the flank.
Copyright © 2024 VisualDx®. All rights reserved.