ContentsSynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyReferencesView all Images (5)
Mycoplasma pneumoniae-induced rash and mucositis in Child
Other Resources UpToDate PubMed

Mycoplasma pneumoniae-induced rash and mucositis in Child

Contributors: Amanda Tillmann MD, Susan Burgin MD
Other Resources UpToDate PubMed


Mycoplasma-induced rash and mucositis (MIRM) is a relatively uncommon mucocutaneous condition resulting from Mycoplasma pneumoniae infection that is characterized by prominent mucositis. MIRM is usually seen in children and adolescents (mean age of approximately 12 years); however, adults of middle age and younger may also be affected. Cases occur more commonly in males than females (ratio of 2:1).

The pathophysiology underlying MIRM remains poorly defined. Direct cytotoxic injury, autoimmune-mediated injury, and immune complex-mediated vascular injury have all been proposed as potential etiological mechanisms. It is speculated that a genetic predisposition is also important. More recent work has postulated that autoantibodies produced as a result of molecular mimicry between M pneumoniae and endogenous proteins cross-react with specific self-antigens that are most abundant in mucous membranes. This theory helps explain why mucositis is such a salient feature. Chlamydia pneumoniae infection has also been suggested as a potential causative agent (C pneumoniae-induced rash and mucositis, or CIRM), sometimes without rash.

Prodromal symptoms of cough, fever, and malaise precede mucocutaneous manifestations by approximately a week. Mucositis is a prominent feature and is usually associated with a sparse, polymorphic eruption.

Complications may include hematemesis, epiglottitis, subcorneal pustulosis, pneumomediastinum, pericardial effusion, and hepatitis.

Ocular sequelae include conjunctival shrinkage, corneal ulceration, blindness, synechiae, dry eyes, and loss of eyelashes. Oral or urogenital adhesions are less common. Pulmonary complications such as restrictive lung disease and chronic obliterative bronchitis have also been observed in MIRM patients.

MIRM is very rarely fatal and has a reported mortality rate of 3%, occurring in cases with significant respiratory disease. Most patients make a full recovery, and both long-term complications and recurrences are infrequent.

Reactive infectious mucocutaneous eruption (RIME) has been proposed as an umbrella term that includes oral erythema multiforme secondary to Mycoplasma pneumoniae, MIRM, and Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) secondary to infection with Mycoplasma species or other respiratory pathogens.


B96.0 – Mycoplasma pneumoniae [M. pneumoniae] as the cause of diseases classified elsewhere

406595002 – Infection caused by Mycoplasma pneumoniae

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

  • The cutaneous involvement of MIRM tends to be much less extensive than in SJS and TEN (<10% of body surface area is usually affected).
  • The cutaneous lesions of MIRM are usually distributed in acral regions compared to SJS and TEN, which exhibit a more central distribution of lesions.
  • The desquamation associated with SJS and TEN is absent in MIRM (Nikolsky sign is negative).
  • MIRM has a much milder course than SJS and TEN, eg, ICU admission is less commonly required.
  • Absence of exposure to a culprit drug favors MIRM, as most cases of SJS and TEN are drug-related.
  • Evidence of atypical pneumonia, including respiratory symptoms, lung auscultation findings, M pneumoniae serology, polymerase chain reaction (PCR), and chest x-ray results, may help support MIRM diagnosis.
Erythema multiforme (EM)
  • The classic target lesions occurring in an acral distribution that are typical of EM are less common in MIRM.
  • Unlike EM, cutaneous lesions may be absent in MIRM.
  • Evidence of atypical pneumonia, including respiratory symptoms, lung auscultation findings, M pneumoniae serology, PCR, and chest x-ray results, may help support MIRM diagnosis.
Fixed drug eruption
  • Typical round morphology is diagnostic.
  • MIRM lacks a temporal relationship to drug exposure.

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required


Subscription Required

Last Reviewed:05/18/2017
Last Updated:03/03/2021
Copyright © 2021 VisualDx®. All rights reserved.
Mycoplasma pneumoniae-induced rash and mucositis in Child
Mycoplasma pneumoniae-induced rash and mucositis : Acral distribution, Targetoid configuration
Copyright © 2021 VisualDx®. All rights reserved.