Derm Cases · Dermatology / Paediatrics / Haematology-oncology
OSCE — seborrhoeic-like scalp and diaper rash: LCH staging, CD1a, BRAF pathway
An 8-minute OSCE on cutaneous LCH mimic of seborrhoeic dermatitis, CD1a/langerin diagnosis, SS vs MS risk-organ staging, and MAPK-targeted therapy concepts.
On this page
Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE on cutaneous LCH mimic of seborrhoeic dermatitis, CD1a/langerin diagnosis, SS vs MS risk-organ staging, and MAPK-targeted therapy concepts.
Brief (to candidate)
A 9-month-old has refractory “cradle cap” and petechial crusted papules in the diaper area; a skull lytic lesion is found on plain film. You have 8 minutes to suspect LCH, plan biopsy IHC, stage risk organs, and outline first-line systemic vs targeted therapy principles.
[9]Candidate instructions
- Recognise cutaneous LCH mimics of seborrhoeic dermatitis/diaper dermatitis.
- State pathognomonic IHC/EM findings.
- Stage single-system vs multi-system and name risk organs.
- Outline first-line therapy concepts for MS-LCH and BRAF V600E options.
- Mention adult pulmonary LCH smoking link.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Clinical suspicion | Refractory seborrhoeic-like crusted papules scalp/flexures/diaper with purpura; bone lesions; diabetes insipidus/exophthalmos triad historically Hand–Schüller–Christian[1] |
| Pathology | Langerhans cells with grooved/coffee-bean nuclei; CD1a+, langerin (CD207)+, S100+; Birbeck granules (tennis-racket) on EM historically; BRAF V600E ~50–60%[1][2] |
| Staging | SS vs MS; risk organs = liver, spleen, bone marrow (RO+) drive prognosis/intensity; CNS-risk bones and DI special pathways[1][5] |
| Therapy | Localised skin/bone may need topical/local measures; MS disease needs systemic chemo protocols (vinblastine/prednisone era backbones per paediatric protocols); prolong therapy improves MS outcomes in classic trials[6] |
| Targeted | BRAF inhibitors (e.g. vemurafenib) / MAPK pathway agents in selected refractory BRAF-mutant disease; MDT haematology-oncology[8] |
| Adult pulmonary | Adult pulmonary LCH strongly smoking-related — smoking cessation essential |
| Safety net | Do not chronically treat “cradle cap” without biopsy if purpuric/erosive or systemic signs |
Model key actions
- Biopsy refractory seborrhoeic/diaper eruption with petechiae for CD1a/langerin.[1]
- Stage for risk-organ multi-system disease before plan.[1][5]
- Escalate systemic/protocol therapy ± BRAF-targeted options for refractory mutant disease.[8]
Common errors
- Prolonged topical steroid for “eczema” without biopsy.
- Missing risk-organ staging (liver/spleen/marrow).
- Ignoring diabetes insipidus / skull lesions.
- Forgetting smoking cessation in adult pulmonary LCH.
References6ShowHide
- [1]Rodriguez-Galindo C, Allen CE. Langerhans cell histiocytosis. Blood, 2020.PMID 32106306
- [2]Moore PF Histiocytic Diseases. Hematol Oncol Clin North Am, 2023.PMID 36270835
- [5]Goyal G, et al. International expert consensus recommendations for the diagnosis and treatment of Langerhans cell histiocytosis in adults. Blood, 2022.PMID 35271698
- [6]Gadner H, et al. Therapy prolongation improves outcome in multisystem Langerhans cell histiocytosis. Blood, 2013.PMID 23589673
- [8]Diamond EL, et al. Vemurafenib for BRAF V600-mutant Erdheim-Chester disease and Langerhans cell histiocytosis. JAMA Oncol, 2018.PMID 29188284
- [9]Haroche J, Cohen-Aubart F, Emile JF, et al. Dramatic efficacy of vemurafenib in both multisystemic and refractory Erdheim-Chester disease and Langerhans cell histiocytosis harboring the BRAF V600E mutation Blood, 2013.PMID 23258922