Derm Cases · Dermatology / Internal medicine / Infectious disease
OSCE — tender shin nodules: diagnose erythema nodosum and find the trigger
An 8-minute OSCE station on septal panniculitis presentation of erythema nodosum, no-ulcer/no-scar signature, trigger search (strep, TB, sarcoid/Löfgren, IBD, drugs, pregnancy), and supportive therapy including when potassium iodide or steroids are used.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on septal panniculitis presentation of erythema nodosum, no-ulcer/no-scar signature, trigger search (strep, TB, sarcoid/Löfgren, IBD, drugs, pregnancy), and supportive therapy including when potassium iodide or steroids are used.
Brief (to candidate)
A 26-year-old woman develops bilateral tender erythematous subcutaneous nodules on the anterior shins after a sore throat; she is febrile and has ankle pain. A second card mentions EN with bilateral hilar lymphadenopathy. You have 8 minutes to diagnose erythema nodosum, exclude mimics, and investigate causes.
[1]Candidate instructions
- Describe classic EN morphology, course, and histology concept.
- Emphasise no ulceration / no scarring and bruise-like resolution.
- List major triggers and a practical work-up algorithm.
- Recognise Löfgren syndrome.
- Outline supportive and directed therapy.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Clinical signature | Bilateral, symmetric, tender erythematous subcutaneous nodules on anterior shins; fever, arthralgia common; resolves through bruise-like colours; no ulceration, no scarring[1] |
| Histology | Septal panniculitis without vasculitis; lobular sparing typical of classic EN[3] |
| Mimics | Nodular vasculitis/erythema induratum (calves, may ulcerate), infectious panniculitis, cutaneous polyarteritis, trauma, other lobular panniculitides |
| Triggers | Idiopathic, streptococcal infection, TB, sarcoidosis, IBD, drugs (e.g. sulphonamides, OCP), pregnancy, Yersinia/other infections regionally; always hunt a cause rather than label idiopathic too early[1][2] |
| Löfgren | EN + bilateral hilar lymphadenopathy ± migratory polyarthritis/fever = acute sarcoidosis phenotype with good prognosis[4] |
| Work-up | History (drugs, GI, cough, travel), ASO/throat assessment, CXR, TST/IGRA as indicated, basic bloods; deeper tests guided by clues (IBD, ACE not diagnostic alone) |
| Therapy | Rest, NSAIDs, treat underlying cause; potassium iodide historically/selected use; short systemic steroids only after excluding infection and for severe disease; most resolve in weeks[1][7] |
Model key actions
- Diagnose EN as tender pretibial septal panniculitis that does not ulcerate or scar.[1][3]
- Run a trigger algorithm (strep, TB, sarcoid, IBD, drugs, pregnancy).[1][2]
- Recognise Löfgren and generally good prognosis.[4]
Common errors
- Calling ulcerating calf nodules EN (think erythema induratum/other).
- Starting steroids before excluding TB/infection.
- Missing CXR for sarcoid/TB in EN work-up.
- Biopsying every classic bilateral pretibial case when clinical diagnosis is clear (biopsy if atypical).
- Treating only the rash and ignoring IBD/systemic clues.
References5ShowHide
- [1]Pérez-Garza DM, Chavez-Alvarez S, Ocampo-Candiani J, et al. Erythema Nodosum: A Practical Approach and Diagnostic Algorithm. American Journal of Clinical Dermatology, 2021.PMID 33683567
- [2]Rogler G, Singh A, Kavanaugh A, et al. Extraintestinal Manifestations of Inflammatory Bowel Disease: Current Concepts, Treatment, and Implications for Disease Management. Gastroenterology, 2021.PMID 34358489
- [3]Wick MR. Panniculitis: A summary. Seminars in diagnostic pathology, 2017.PMID 28129926
- [4]Abdelghaffar M, Hwang E, Damsky W. Cutaneous Sarcoidosis. Clinics in chest medicine, 2024.PMID 38245372
- [7]Goel N, Doshi BR Potassium Iodide in Dermatology- Recent Advances in Mechanism of Action, Preparation, Uses and Adverse Effects. Indian journal of dermatology, 2025.PMID 40487487