SAEM Clinical Images Series: A Mucous Membrane Mystery

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The patient is a healthy 14-year-old male without past medical history who presents to the Emergency Department with oral lesions, eye swelling, intermittent fevers, and pain with urination. Over the past 10 days he has been seen by his PCP and at an outside ED for a cough, sore throat, fevers, and oral pain. Three days ago he was seen by his PCP, had a positive rapid strep test, and was started on amoxicillin. His oral lesions and lip swelling have been progressively worsening over the past 2 days. Monospot testing was also performed yesterday and is negative. Today he was seen again by his PCP for new pain with urination and was sent to the ED for concern for Kawasaki disease. The patient has had decreased oral intact due to his pain, but otherwise has no other complaints.

Additional Images

Physical Exam

Vitals: BP 124/88 HR 112 R 28 T 100.2 F O2sat 94% room air.
HEENT: Relevant findings are shown in the images provided. Tonsillar exudate is present. No meningismus. Voice is normal.
Respiratory: Coarse breath sounds with diffuse wheezing.
Cardiovascular: Tachycardic, no murmurs, no rubs.
Skin: No rash. Negative Nikolsky sign. No palmar desquamation.
Lymph: Cervical lymphadenopathy is present
Genitourinary: See image provided.

Laboratory Data

CBC, CMP, Urinalysis: negative

COVID/Flu/RSV: negative

Mycoplasma NAAT: positive.

CRP: 13.5 mg/L

ESR: 48 mm/Hr

Case Question: What is the most likely diagnosis?

This child has RIME (reactive infections mucocutaneous eruption), a rare post-infectious cause of mucositis in children and adolescents.

Case Question: What pathogen is most frequently associated with this diagnosis?

Mycoplasma pneumoniae

Case Discussion

Prolonged fevers and illnesses are frequent reasons for pediatric ED visits. Children and adolescents can be more prone than adults to a variety of immune-mediated and other inflammatory reactions such as Kawasaki disease, serum sickness like reactions, erythema or urticaria multiforme, SJS/TEN, MISC, among others. RIME is a relatively recently described post-infectious condition characterized by mucositis in at least two mucus membranes, with or without an area of cutaneous eruption. It was previously called mycoplasma-induced rash and mucositis (MIRM), and mycoplasma is the most common trigger, though the designation RIME implies that other common infectious agents (covid, influenza, and other viral and bacterial pathogens) have been identified as causal agents. Management is supportive, including treatment of the underlying illness (in this case, treatment of mycoplasma). Corticosteroids and other immunomodulatory agents may be used in more severe cases.

Take-Home Points

RIME is a reaction primarily involving mucosal surfaces that is often associated with Mycoplasma pneumoniae infections in pediatric populations.
Treatment of RIME involves treating Mycoplasma pneumoniae with azithromycin and supportive care including hydration and appropriate consultations for wound management as needed.

References

Lofgren D, Lenkeit C. Mycoplasma Pneumoniae-Induced Rash and Mucositis: A Systematic Review of the Literature. Spartan Med Res J. 2021 Aug 30;6(2):25284. doi: 10.51894/001c.25284. PMID: 34532621; PMCID: PMC8405277.
Meyer Sauteur PM, Theiler M, Buettcher M, Seiler M, Weibel L, Berger C. Frequency and Clinical Presentation of Mucocutaneous Disease Due to Mycoplasma pneumoniae Infection in Children With Community-Acquired Pneumonia. JAMA Dermatol. 2020 Feb 1;156(2):144-150. doi: 10.1001/jamadermatol.2019.3602. PMID: 31851288; PMCID: PMC6990853.
Rehmus, W. E., Phillips, J., & Flegel, L. (2023). In Pediatric Dermatology (pp. 274–274). essay, UBC LIBRARY. Retrieved January 6, 2025,.

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2025 SAEM Annual Meeting | Copyrighted by SAEM 2025 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.