Published on 18/03/2015 by admin
Filed under Dermatology
Last modified 22/04/2025
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Preston W. Chadwick and Warren R. Heymann
Evidence Levels: A Double-blind study B Clinical trial ≥ 20 subjects C Clinical trial < 20 subjects D Series ≥ 5 subjects E Anecdotal case reports
Miliaria is a benign, transient disorder caused by occlusion in the eccrine duct. It is subdivided into miliaria crystallina, miliaria rubra, and miliaria profunda, based on the level of obliteration. Miliaria crystallina, the most superficial form (sudamina), occurs with occlusion of the sweat duct in the stratum corneum. It is self-limiting and typically appears as clear vesicles without significant erythema. Miliaria rubra (‘prickly heat’) is the most common, presenting as numerous pruritic non-follicular papules or vesicles with surrounding erythema. The obstruction occurs within the eccrine duct in the stratum malpighii. Typically it occurs on the trunk, neck, or back, but can affect other areas and has been reported to occur under splints or braces and military uniforms because of the warm occlusive environment. Miliaria profunda is more uncommon, the occlusion occurring at the dermoepidermal junction or dermis. Miliaria profunda is typically seen after repeated cases of miliaria rubra in tropical settings. These patients can also have associated systemic symptoms related to overheating.
Miliaria most typically occurs as a result of excessive sweating in hot, humid conditions, prolonged perspiration, or following extended febrile illness. There are other less common reports of congenital miliaria, miliaria occurring after medication administration in the intensive care setting, and in association with congenital illnesses such as pseudohypoaldosteronism. Miliaria is often exacerbated by tight clothing and high humidity. Management begins with removal of the inciting factors. There is no strong evidence for the various treatment options.
Adults often develop miliaria during travel in the tropics, military service or with heavy exercise. Gradual exposure helps to acclimatize to a hot and humid environment, but this may take a few months. Loose-fitting clothing, fans and cool showers may minimize the symptoms. With the use of any topical lotion or cream, care must be taken to ensure that the product applied does not occlude the skin, further exacerbating the condition. In the case of severe itching, antihistamines, cold packs, and topical corticosteroids may be used. Oatmeal baths have been anecdotally reported to provide relief. However, all these measures will prove ineffective if the sweating is not reduced. All cases will respond to air-conditioning, exposure of the involved skin, and the use of antipyretics, in appropriate circumstances. Miliaria profunda has been reported to respond to oral retinoids and anhydrous lanolin.
Miliaria may be complicated by superinfection; it should be treated with systemic antibiotics aimed at staphylococci as the likely pathogen. Clinicians should make patients aware that anhidrosis in the area of the eruption may occur and persist up to 3 weeks (or sometimes even longer) after the onset of lesions, and increased heat retention may occur if a large surface area was initially affected. Thus, patients at risk of heat exhaustion or heat stroke should take precautions to remain in air-conditioned environments during hot weather. A biopsy may be helpful in atypical cases of miliaria.
None usually required
In atypical cases:
Microbiology – swab for bacteria and yeasts
Histology
Wenzel FG, Horn TD. J Am Acad Dermatol 1998; 38: 1–7.
The histology and pathophysiology of eccrine sweat ducts are reviewed. The erythematous macule or papule of miliaria rubra occurs with an obstruction of the sweat duct at the stratum malpighii. In the case of miliaria crystallina the disruption is in the stratum corneum, and, with miliaria profunda, at or beneath the dermoepidermal junction. The pathogenesis of miliaria is reviewed, describing the role of resident bacteria and PAS-positive extracellular polysaccharide substance blocking eccrine ducts.
Shuster S. Acta Derm Venereol 1997; 77: 1–3.
An hypothesis is presented that ascribes miliaria crystallina to mechanical disruption of the eccrine duct, rather than the commonly accepted pathogenesis of duct plugging. This disruption is attributed to UV irradiation causing a split between upper epidermal cells and stratum corneum.
Mowad CM, McGinley KJ, Foglia A, Leyden JJ. J Am Acad Dermatol 1995; 33: 729–33.
The ability of various strains of coagulase-negative staphylococci to induce miliaria under an occlusive dressing was evaluated. Staphylococcus epidermidis was the only strain that induced miliaria. The authors conclude that periodic acid–Schiff (PAS)-positive extracellular polysaccharide substance produced by S. epidermidis plays a central role in the pathogenesis of miliaria by obstructing sweat delivery.
Allen HB, Meuller JL. Int J Dermatol 2011; 50: 992–3.
S. epidermidis biofilm was cultured in a patient with atopic dermatitis. The authors proposed subclinical miliaria contributes to pruritus in atopic patients.
Holzle E, Kligman AM. Br J Dermatol 1978; 99: 117–37.
The degree of miliaria rubra and anhidrosis induced in 55 subjects was shown to be directly correlated with the density of resident flora present on occluded areas of skin, as measured by detergent scrub and culture. An historical overview of research into the pathogenesis of miliaria rubra is included.
Haas N, Martens F, Henz BM. Clin Exp Dermatol 2004; 29: 32–4.
Two cases of miliaria crystallina occurring in an intensive care setting are presented. The authors hypothesize that the mechanism is secondary to transient poral closure due to the drugs used in the intensive care setting that may have stimulated sweating.
LaShell M, Tankersley M, Guerra A. Ann Allergy Asthma Immunol 2007; 98: 299–302.
This article reviews common exercise-induced eruptions, with miliaria rubra being discussed as the cause of the patient’s recurring, self-limited eruption occurring with indoor exercise or hot tub exposure. Exercise challenge recreated the clinical picture and confirmed the diagnosis.
Nguyen, TA, Stevens, MP. An Bras Dermatol 2011; 86: 104–6.
A 40-year-old female developed miliaria crystallina after developing neutropenic fevers while on treatment with idarubicin and cytarabine. Treatment of the underlying fever led to resolution of cutaneous lesions. A review of miliaria and excessive perspiration associated with medications including doxorubicin, bethanechol, salbutamol, and clonidine are discussed.
Akcakus M, Koklu E, Poyrazoglu H, Kurtoglu S. Int J Dermatol 2006; 45: 1432–4.
Autosomal recessive type I pseudohypoaldosteronism as a cause of miliaria is discussed in a patient who developed miliaria rubra specifically during salt depletion crises. The rash cleared after stabilization of electrolytes and reappeared upon hyponatremia. The miliaria rubra seen in this patient was felt to be due to high concentrations of sodium chloride in the sweat directly damaging eccrine ducts.
Donoghue AM, Sinclair MJ. Occup Med (Lond) 2000; 50: 430–3.
Case series of 25 miners working in a hot and humid environment who developed miliaria. Symptoms resolved after 4 weeks of sedentary duties in the air-conditioned areas. This report also analyzed coexisting dermatological conditions in these patients.
Miller JL. In: Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. Philadelphia: Mosby, 2012; 34–11.
Preventative measures, such as a cool environment, for days to weeks is the primary goal to prevent excessive sweating and maceration of the stratum corneum.
Dimon NS, Fullen DR, Helfrich YR. Arch Dermatol 2007; 43: 1323–8.
Numerous treatments for miliaria are described, including anhydrous lanolin, oral isotretinoin, regular bathing to remove salt and bacteria, and antibiotics.
Babu TA, Sharmila V. Pediatr Dermatol 2011; 1–2 [Epub ahead of print].
A case report of a full term infant, whose birth was complicated by chorioamnionitis, presented at delivery with miliaria crystallina that self-resolved in 3 days. The authors proposed that prolonged rupture of membranes, maternal fever and warm amniotic fluid may have contributed to fetal sweating and development of miliaria. Conservative and preventative measures are emphasized.
Siddiqi A. In: Domino FJ, ed. 5-Minute Clinical Consult (online). Philadelphia: Lippincott, Williams & Wilkins, 2012; 1–4.
For relief of pruritus, 0.1% betamethasone twice daily for 3 days may be applied over the affected area. In the event of superimposed infection, an anti-staphylococcal agent such as dicloxacillin (flucloxacillin) 250 mg four times daily for 10 days may be used.
Platt M, Vicario S. In: Marx JA, ed. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edn. Vol 2. Philadelphia: Mosby, 2009; 1887.
If a case of miliaria rubra becomes diffuse or pustular, oral erythromycin has been shown to be helpful. During the most acute phase of miliaria rubra, chlorhexidine lotion or cream can be used as an antibacterial agent, with salicylic acid 1% three times daily over small areas to aid in desquamation (not to be used in children).
Kirk JF, Wilson BB, Chun W, Cooper PH. J Am Acad Dermatol 1996; 35: 854–6.
This case report describes a 23-year-old man with miliaria profunda successfully treated with both anhydrous lanolin and isotretinoin, after a poor response to topical corticosteroids. The impact of either as an individual treatment is therefore difficult to assess.
Hindson TC, Worsley DE. Br J Dermatol 1969; 81: 226–7.
Miliaria and hypohidrosis were induced in 36 subjects, half of whom were given 1 g daily of ascorbic acid and half a placebo, beginning on the day of wrapping the skin with polythene occlusion. Compared to the placebo group the ascorbic acid group developed less severe miliaria and hypohidrosis, had quicker healing of visible lesions, and notable improvement in hypohidrosis at 1 week.
Carter R, Garcia AM, Souhan BE. J Med Case Reports 2011; 5: 474.
Two cases of miliaria rubra are reported in military personnel wearing flame-resistant army combat uniforms (FRACU) in arid environments. Both patients received 250 mg intramuscular methylprednisolone and one was continued on triamcinolone acetonide 0.1% cream twice daily for 1 week. Resolution was achieved; however, relapse with repeated FRACU use occurred.
Treatment of Skin Disease Comprehensive Therapeutic Strategies 4e
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Prevention
Frequent showering
Air conditioning
Oatmeal baths
Topical antiseptics
Antipyretics
Topical corticosteroids
Systemic antibiotics
Anhydrous lanolin/isotretinoin
Ascorbic acid
Intramusular steroids
