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)