Derm Cases · Dermatology / Paediatrics / Tropical medicine
OSCE — heat rash: crystallina vs rubra vs profunda and cooling first
An 8-minute OSCE station on miliaria subtypes by depth of sweat-duct obstruction, neonatal and tropical presentations, cooling-centred management, and rare thermoregulatory failure with miliaria profunda.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on miliaria subtypes by depth of sweat-duct obstruction, neonatal and tropical presentations, cooling-centred management, and rare thermoregulatory failure with miliaria profunda.
Brief (to candidate)
A febrile neonate under a radiant warmer develops crops of clear fragile vesicles without inflammation. An adult in humid heat has intensely pruritic red papules under occlusive clothing. A soldier has flesh-coloured deep papules and reduced sweating with heat intolerance. You have 8 minutes to subtype miliaria and manage appropriately.
Candidate instructions
- Explain miliaria as eccrine duct obstruction.
- Differentiate crystallina, rubra, profunda.
- Give first-line environmental management.
- Avoid unnecessary antibiotics/steroids when not indicated.
- Recognise thermoregulatory failure risk in profunda.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Mechanism | Obstruction of eccrine sweat duct with sweat leakage into epidermis/dermis; heat, humidity, occlusion, fever, incubators trigger[4] |
| Crystallina | Superficial clear non-inflammatory vesicles (stratum corneum); common neonate; self-limited with cooling; not infectious vesicles primarily[1][2][3] |
| Rubra | Mid-epidermal pruritic erythematous papules ("prickly heat") in occluded sites; cool environment, loose clothing, avoid heavy oils that further block ducts |
| Profunda | Deeper pale papules, hypohidrosis, risk of heat exhaustion/stroke in extremes — rare but serious; cooling/environment critical[5] |
| Therapy | Cooling, reduce occlusion, lightweight clothing; mild topical anti-inflammatories if needed; treat secondary infection (pustulosa) only if present — not routine systemic antibiotics |
| DDx | Neonatal HSV/bacterial sepsis if sick; miliaria vs transient neonatal pustular melanosis/erythema toxicum by morphology and context |
| Communication | Reassure parents of crystallina; teach heat-avoidance; safety-net fever/lethargy |
Model key actions
- Call neonatal clear vesicles under warmer miliaria crystallina and cool the infant.[1][2]
- Manage rubra with environment first, not antibiotics alone.[4]
- Respect profunda as a heat-illness risk state.[5]
Common errors
- Antibiotics for crystallina.
- Occlusive oily emollients worsening duct blockage.
- Missing heat illness with extensive profunda.
- Confusing with viral exanthem without exam of distribution/occlusion history.
References5ShowHide
- [1]O'Connor NR, McLaughlin MR, Ham P. Newborn skin: Part I. Common rashes. American Family Physician, 2008.PMID 18236822
- [2]Palaniappan V, Sadhasivamohan A, Sankarapandian J, et al. Miliaria crystallina. Clinical and experimental dermatology, 2023.PMID 36692206
- [3]Chadha A, Jahnke M. Common Neonatal Rashes. Pediatric annals, 2019.PMID 30653638
- [4]Feng E, Janniger CK. Miliaria. Cutis, 1995.PMID 7796612
- [5]Kirk JF, Wilson BB, Chun W, et al. Miliaria profunda. Journal of the American Academy of Dermatology, 1996.PMID 8912605