Derm Cases · Dermatology / Psychiatry / Liaison
OSCE — psychodermatology: delusional infestation, dermatitis artefacta, and skin-picking disorders
An 8-minute OSCE station on recognising primary psychiatric dermatoses (delusional infestation, dermatitis artefacta, body-focused repetitive behaviours), excluding organic disease, building rapport, and planning combined dermatology–psychiatry care without colluding with false beliefs.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on recognising primary psychiatric dermatoses (delusional infestation, dermatitis artefacta, body-focused repetitive behaviours), excluding organic disease, building rapport, and planning combined dermatology–psychiatry care without colluding with false beliefs.
Brief (to candidate)
A 52-year-old is convinced insects crawl under the skin and brings a container of “specimens” (matchbox sign). Exam shows excoriations without primary burrows; microscopy of specimens shows keratin debris. A second patient has geometric erosions in reachable sites. You have 8 minutes to assess, communicate, and plan management.
Candidate instructions
- Differentiate delusional infestation, dermatitis artefacta, neurotic excoriations/skin picking, and true infestation.
- Perform respectful exam and specimen review without mockery.
- Avoid premature confrontation; plan shared care with psychiatry.
- Consider organic differentials (scabies, contact dermatitis, neuropathy).
- Pharmacologic options concepts (antipsychotics for delusional infestation in specialist pathways).
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Delusional infestation | Fixed false belief of infestation; matchbox sign (brought specimens); secondary excoriations; specimens typically negative for parasites — diagnose clinically after excluding true infestation[1][2] |
| Dermatitis artefacta | Self-induced lesions, often geometric/bizarre shapes on accessible skin; denial of production; associated psychosocial stressors — sensitive non-accusatory approach[3] |
| Skin picking / BFRB | Insight often partial; pick acne/scabs; overlap OCD-spectrum — behavioural therapy ± SSRIs as indicated |
| Organic exclusion | Re-examine for scabies, dermatitis herpetiformis, bullous disease prodrome, neuropathy; basic labs if systemic clues; do not miss real parasites in contacts/institutions |
| Communication | Validate distress and itch/pain; agree to treat skin barrier/secondary infection; avoid saying “it’s all in your head”; carefully introduce brain–skin/nerve framing and specialist help |
| Treatment frame | Emollients, treat secondary infection, consider low-dose antipsychotic pathways (e.g. risperidone/olanzapine historically used) with psychiatry; risk of non-engagement if forcibly confronted early[2][4] |
| Risk | Suicide risk/self-harm screen; safeguarding if artefacta in minors; polypharmacy/drug-induced delusional states review |
Model key actions
- Recognise delusional infestation with matchbox sign after excluding true scabies/other dermatoses.[1][2]
- Use non-colluding, non-humiliating communication and offer joint dermatology–psychiatry care.[4]
- Identify artefactual geometric lesions and skin-picking patterns with safeguarding awareness.[3]
Common errors
- Mocking the patient or refusing any skin care.
- Fully colluding (“yes, parasites confirmed”) without evidence.
- Missing real scabies outbreak.
- No psychiatry/risk pathway.
- Confrontational early “you’re delusional” rupture of rapport.
References6ShowHide
- [1]França K, Lotti TM. Psycho-Neuro-Endocrine-Immunology: A Psychobiological Concept. Advances in Experimental Medicine and Biology, 2017.PMID 29124696
- [2]Yoon KN, Chung JH. Healthy skin, Healthy brain. Journal of Dermatological Science, 2025.PMID 40681402
- [3]Mar K, Rivers JK. The Mind Body Connection in Dermatologic Conditions: A Literature Review. Journal of Cutaneous Medicine and Surgery, 2023.PMID 37898903
- [4]Brown GE, Malakouti M, Sorenson E, et al. Psychodermatology. Advances in Psychosomatic Medicine, 2015.PMID 25832518
- [5]Šitum M, Kolić M, Buljan M. [PSYCHODERMATOLOGY]. Acta Medica Croatica, 2016.PMID 29087669
- [6]Freudenmann RW, Lepping P. Delusional infestation. Clinical Microbiology Reviews, 2009.PMID 19822895