Derm Cases · Dermatology / Infectious triggers
OSCE — target lesions after cold sores: erythema multiforme vs SJS and MIRM
An 8-minute OSCE station on classic target lesions of erythema multiforme, HSV and Mycoplasma triggers, distinction from SJS/TEN and MIRM, and supportive plus suppressive management.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on classic target lesions of erythema multiforme, HSV and Mycoplasma triggers, distinction from SJS/TEN and MIRM, and supportive plus suppressive management.
Brief (to candidate)
A 22-year-old man develops raised target lesions on the palms and extremities 3 days after a herpes labialis outbreak. He has mild oral erosions, is afebrile and well, with no epidermal sheet detachment. You have 8 minutes to diagnose, exclude dangerous mimics, and manage.
Candidate instructions
- Recognise typical target lesions of EM.
- Identify the most common trigger (HSV) and when to think Mycoplasma/MIRM.
- Distinguish EM from SJS/TEN.
- Outline acute management and when to admit.
- Plan prevention for recurrent EM.
- Eye/mucosal safety-net.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Recognition | Acute typical targets (three concentric zones) on acral/extensor skin ± limited mucosa; usually self-limited immune-mediated eruption[1][2] |
| Triggers | HSV commonest for EM minor; drugs less often primary for classic EM; respiratory symptoms + prominent mucositis in youth → consider Mycoplasma/MIRM and macrolide pathway[1][3] |
| Vs SJS/TEN | SJS/TEN: severe mucosal disease, skin pain, epidermal detachment/Nikolsky, often drug-triggered — different emergency pathway; do not label extensive necrolysis as EM[1][4] |
| MIRM | Mycoplasma-induced rash and mucositis: mucositis-predominant, may have sparse skin lesions; treat infection + supportive care; distinct from SJS in many frameworks[3] |
| Acute Rx | Supportive care, analgesia, oral care; treat active HSV if present; short systemic steroids sometimes used for severe mucosal pain (case-by-case); admit if unable to drink or eye involvement[1][6] |
| Recurrent EM | ≥6 episodes/year: continuous antiviral suppression after HSV work-up (PCR/serology as appropriate)[1][2] |
| Communication | Reassure usual self-limited course; urgent review if skin pain, blistering sheets, severe eye symptoms, or inability to hydrate |
Model key actions
- Diagnose EM minor with post-HSV target lesions and limited mucosa.[1][2]
- Explicitly exclude SJS/TEN red flags (detachment, severe multi-site mucositis, culprit drug).[1]
- Supportive care ± HSV treatment; suppress recurrent disease; consider MIRM when respiratory + mucositis dominate.[3][6]
Common errors
- Labelling SJS/TEN as "severe EM" and missing burn-unit pathway.
- Missing HSV history and not offering suppression for frequent recurrence.
- Ignoring ocular symptoms.
- Treating every EM as a drug allergy without considering infection triggers.
- Discharging a patient who cannot maintain oral intake.
References6ShowHide
- [1]Trayes KP, Love G, Studdiford JS. Erythema Multiforme: Recognition and Management. American Family Physician, 2019.PMID 31305041
- [2]Kechichian E, Dupin N, Wetter DA, et al. Erythema multiforme. EClinicalMedicine, 2024.PMID 39583748
- [3]Canavan TN, Mathes EF, Frieden I, et al. Mycoplasma pneumoniae-induced rash and mucositis as a syndrome distinct from Stevens-Johnson syndrome and erythema multiforme: a systematic review. Journal of the American Academy of Dermatology, 2015.PMID 25592340
- [4]Del Pozzo-Magaña BR, Liy-Wong C. Drugs and the skin: A concise review of cutaneous adverse drug reactions. British Journal of Clinical Pharmacology, 2024.PMID 35974692
- [6]Soares A, Sokumbi O. Recent Updates in the Treatment of Erythema Multiforme. Medicina (Kaunas), 2021.PMID 34577844
- [7]Ramien ML, Bruckner AL. Mucocutaneous Eruptions in Acutely Ill Pediatric Patients-Think of Mycoplasma pneumoniae (and Other Infections) First JAMA Dermatol, 2020.PMID 31851301