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Milaria
From WikiSM
Contents
Other Names
- Heat Rash
- Miliaria
- Lichen Tropicus
- Prickly Heat
- Eccrine miliaria
- Milaria Rubra
- Milaria Profunda
- Milaria Crystallina
Background
- This page refers to Miliaria, a self-limited condition commonly referred to as 'Heat Rash' or 'Prickly Heat'
History
Epidemiology
Pathophysiology

Heat rash seen on the trunk[3]

More heat rash seen on the trunk[4]
- General
- Self limited condition seen in athletes in hot, humid weather wearing tight fitting clothing
- Most commonly occurs under conditions of sweating
Etiology
- General
- Acute inflammation of sweat ducts due to blockage of pores by macerated skin
- Ducts in the stratum corneum become dilated under pressure, rupture
- Often seen in areas of friction
- Subsequently, superficial vesicles in palpghian layer of skin
- Can progress to white papules (miliaria profunda) if duct ruptures a second times
Types
- Milaria Rubra
- Most common form
- Milaria Profunda
- Kertain plug develops in the obstructed poor, produces deeper vesicle within the dermis
- Occurs days to weeks after initial rash
- Miliary Crystallina
- Sometimes called sudamina
- Common in neonates
Risk Factors
- Environmental
- High Ambient Temperature
- High Humidity
- Lack of acclimitization to new environment
- Activity/ Training
- Sustained physical exertion
- Intense exercise
- Occlusive clothing
- Other
- Hyperhydrosis
Differential Diagnosis
Differential Diagnosis of Rash
- Viral infection, specifically herpes or varicella
- Bacterial infection, specifically folliculitis
- Acne Vulgaris
- Drug reaction
- Viral exanthem
- Allergic reaction
- Cholinergic urticaria
- Rhus dermatitis
Differential Diagnosis Heat Illness
- Minor
- Major

Miliaria Profunda seen in the popliteal fossa two weeks after the initial appearance of rash[5]
Clinical Features
- History
- Patients should describe a history of working or exercising in hot, humid conditions
- They often report intense pruritis
- Anhidrosis of affected areas
- Onset is typically rapid
- Physical Exam[6]
- Rash: pruritic, maculopapular, erythematous rash
- 2-4 mm papules or vesicles superimposed on an erythematous background
- In distribution of clothed areas of body
- Also common in waist or high sweaty or friction areas (neck, trunk, axilla, groin, waist)
- Note that folliculitis can present similarly
- Keratin plugs can develop days to weeks after initial rash (profunda stage)
Evaluation
- Clinical diagnosis, no work up is required
Classification
- Not applicable
Management
- Mild cases
- Condition is self limiting and will resolve spontaneously
- Moving to cooler environment, removing constrictive clothing is often all that is needed
- Gentle exfoliation can help open obstructed pores
- Moderate to Severe cases
- Distinguished by formation of pustules rather than vesicles
- Topical corticosteroids may help
- E.g. Hydrocortisone cream BID for 7 days
- Topical or oral antibiotics should be considered if bacterial infection is suspected
- Treating pruritis consider:
- Oral antihistamines
- Calamine Lotion
- Anhydrous lanolin
- Wet compresses
- Chlorhexadine
- Menthol-based
- Camphore- based
- Prevention
- Wear light, loose-fitting clothing
- Avoid exercising in high heat or humid environments
- Exercise in air conditioned or cool climates
- Frequent cool showers or baths with mild soap
Rehab and Return to Play
Rehabilitation
- Not specific rehabilitation guidelines
Return to Play/ Work
- Self limited condition
Complications and Prognosis
Prognosis
- Recurrence
- High likelihood of recurring
- Risk of recurrence decreases with acclimitization
Complications
- Secondary Infection/ Folliculitis
- Typically seen with Staph or Strep
See Also
References
- ↑ Hidano, Akira, Ratna Purwoko, and Kumiko Jitsukawa. "Statistical survey of skin changes in Japanese neonates." Pediatric dermatology 3.2 (1986): 140-144.
- ↑ LYONS, ROBERT E., ROBERT LEVINE, and DAVID AULD. "Miliaria rubra: a manifestation of staphylococcal disease." Archives of Dermatology 86.3 (1962): 282-286.
- ↑ Image courtesy of sportsmedschool.com, "Heat Rash"
- ↑ Image courtesy of NHS.uk, "Heat Rash"
- ↑ Carter, Robert, Anisa M. Garcia, and Brian E. Souhan. "Patients presenting with miliaria while wearing flame resistant clothing in high ambient temperatures: a case series." Journal of Medical Case Reports 5.1 (2011): 1-4.
- ↑ Howe, Allyson S., and Barry P. Boden. "Heat-related illness in athletes." The American Journal of Sports Medicine 35.8 (2007): 1384-1395.
Created by:
John Kiel on 30 June 2019 22:48:01
Authors:
Last edited:
31 August 2022 15:03:13
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