Miliaria

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Miliaria
Other namesSweat rash, [1] heat rash, prickly heat
Miliaria rubra mild.jpg
Typical red spots on chest, neck, and shoulders, caused by miliaria rubra
Pronunciation
Specialty Dermatology

Miliaria, commonly known as heat rash, sweat rash, or prickly heat, [1] is a skin disease marked by small, itchy rashes due to sweat trapped under the skin by clogged sweat-gland ducts. Miliaria is a common ailment in hot and humid conditions, such as in the tropics and during the summer. [2] Although it affects people of all ages, it is especially common in children and infants due to their underdeveloped sweat glands.

Contents

Signs and symptoms

Miliaria rubra in a forehead Miliaria.jpg
Miliaria rubra in a forehead

Symptoms of miliaria include small, red rashes, called papules, which are irritated and itchy. These may simultaneously occur at a number of areas on a patient's body, the most common including the upper chest, neck, elbow creases, under the breasts, and under the scrotum. [3] Other areas include skin folds and areas of the body that may rub against clothing, such as the back, chest, and stomach. A related and sometimes simultaneous condition is folliculitis, where hair follicles become plugged with foreign matter, resulting in inflammation.

The symptoms relating to miliaria should not be confused with shingles, as they can be very similar. Shingles is limited to one side of the body, but also has a rash-like appearance. It is also accompanied by a prickly sensation and pain throughout the region. Those who suspect they have shingles and not miliaria should seek medical advice immediately as the sooner antivirals are taken, the better.

Types

Miliaria can be classified according to the top level at which obstruction occurs in the sweat glands.

Miliaria crystalline

The most superficial obstruction (with the most mild clinical presentation), is known as miliaria crystalline; instead of a rash, the patient presents with multiple, tiny, blister-like lesions that look like beads of perspiration and essentially cause no symptoms. [4] :23 [5] Miliaria crystalline is also known as miliaria crystallina, [6] and sudamina. The superficial vesicles are not associated with an inflammatory reaction. [4] :23

Miliaria rubra

The most commonly encountered form of the illness is miliaria rubra, in which obstruction causes leakage of sweat into the deeper layers of the epidermis, provoking a local inflammatory reaction and giving rise to the typical appearance of redness (hence rubra) and larger (but still only a few millimetres), blister-like lesions. This form of the illness is often accompanied by the typical symptoms—intense itching or "pins and needles" with a lack of sweating (anhidrosis) to affected areas. [4] :23 A small risk of heat exhaustion exists due to inability to sweat if the rash affects a large proportion of the body's surface area or the patient continues to engage in heat-producing activity. Miliaria rubra is also known as prickly heat and heat rash. [6] Differential diagnosis should be used to rule out polycythemia vera, which is a rare hematological disorder and appears more often in males than females, generally not before the age of 40. Both disorders share a common trait of appearing after taking a hot shower.[ citation needed ]

Miliaria profunda

The most severe form of miliaria, miliaria profunda, sometimes referred to as "wildfire" due to the rapid spread and severe burning sensations, generally occurs as a complication of repeated episodes of miliaria rubra. The obstruction is deep in the structure of the sweat gland, causing the gland's secretions to leak between the superficial and deep layers of the skin. The rash and associated symptoms tend to appear within hours of an activity provoking sweating, but similarly fade within hours when the stimulus for the sweating is removed. Miliaria profunda is characterised by nonpruritic, flesh-coloured, deep-seated, whitish papules. [4] :24 The rash tends to be flesh-coloured as opposed to the prominent redness of miliaria rubra, and the risk of heat exhaustion is larger. Miliaria profunda is also less commonly known as "mammillaria" [6] :chapter 40 [7]

Miliaria pustulosa

Miliaria pustulosa describes pustules due to inflammation and bacterial infection. [8] Miliaria pustulosa is preceded by another dermatitis that has produced injury, destruction, or blocking of the sweat ducts. [4] :23

Postmiliarial hypohidrosis

Postmiliarial hypohidrosis is a skin condition that results from occlusion of sweat ducts and pores, and may be severe enough to impair an individual's ability to perform sustained work in a hot environment. [4] :24

Tropical anhidrotic asthenia

Tropical anhidrotic asthenia is a skin condition, a rare form of miliaria, with long-lasting poral occlusion, which produces anhidrosis and heat retention. [4] :24 [6]

Occlusion miliaria

Occlusion miliaria is a skin condition that is accompanied by anhidrosis and increased heat-stress susceptibility, all after the application of extensive polyethylene film occlusion for 48 hours or longer. [4] :24

Colloid milium

Colloid milium is a skin condition characterized by a translucent, flesh-colored, or slightly yellow, 1 to 5 mm papules. [4] :31

Pathophysiology

Miliaria occurs when sweat glands become clogged due to dead skin cells or bacteria such as Staphylococcus epidermidis , [9] a common bacterium that occurs on the skin, which is also associated with acne.

The trapped sweat leads to irritation (prickling), itching, and a rash of very small blisters, usually in a localized area of the skin.

Prevention

Prickly heat can be prevented by avoiding activities that induce sweating, using air conditioning to cool the environment, [10] wearing light clothing, and in general, avoiding hot and humid weather. Frequent cool showers or cool baths with mild soap can help to prevent heat rash.

Treatment

The primary remedy for prickly heat or rash is to wear lighter clothing, or otherwise avoid overheating one's body. The immediate treatment of the involved skin areas involves the use of a soothing ointment, such as calamine lotion.

Medical assistance should be sought for the first episode of a rash with the appearance of miliaria. The differential diagnosis includes several conditions that an experienced practitioner should be able to recognise and may require treatment distinct from the usual measures taken for miliaria. In most cases, the rash of miliaria resolves without intervention, but severe cases can last for weeks and cause significant disability. General measures should be recommended for all patients, including moving to an air-conditioned environment if possible, avoiding sweat-provoking activities and occlusive clothing, and taking frequent, cool showers.

The use of topical antibacterials (including antibacterial soaps) may shorten the duration of symptoms in miliaria rubra even in the absence of obvious superinfection. Other topical agents that may reduce the severity of symptoms include anti-itch preparations such as calamine or menthol- or camphor-based preparations, and topical steroid creams. Caution should be used, however, with oil-based preparations (ointments and oily creams as opposed to water-based or aqueous lotions) that may increase blockage of the sweat glands and prolong the duration of illness. Other agents have been investigated including supplemental vitamin A and C and vitamin A based medications, but little scientific evidence supports any of the above treatments in reducing the duration of symptoms or frequency of complications.

In most tropical areas, the local dispensaries sell prickly heat powder, a talc admixture containing drying milk proteins (labilin) and Triclosan to fight bacterial infection. These include cooling menthol to help alleviate difficulty getting to sleep. This is an effective treatment; the powder stays on the skin longer and treats bacteria dispersed into bed linens, providing a reasonably dry refuge area for healing. Miliaria often covers large areas, and generous use of cortisone may be contraindicated for reasons stated on package warnings. Regular talcum powder does not reduce the rash, but can alleviate burning and itching. In cases where the rash has developed into open blisters or pustular lesions, a doctor should be consulted since more aggressive, medically monitored treatment may be required.

See also

Related Research Articles

<span class="mw-page-title-main">Perspiration</span> Fluid secreted from sudoriferous glands

Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals.

<span class="mw-page-title-main">Irritation</span> State of inflammation

Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritants are typically thought of as chemical agents but mechanical, thermal (heat), and radiative stimuli can also be irritants. Irritation also has non-clinical usages referring to bothersome physical or psychological pain or discomfort.

<span class="mw-page-title-main">Sebaceous hyperplasia</span> Medical condition

Sebaceous hyperplasia is a disorder of the sebaceous glands in which they become enlarged, producing flesh-colored or yellowish, shiny, often umbilicated bumps on the face. Newly formed nodules often swell with sweating, but this diminishes over time.

<span class="mw-page-title-main">Tinea cruris</span> Fungal infection

Tinea cruris, also known as jock itch, is a common type of contagious, superficial fungal infection of the groin and buttocks region, which occurs predominantly but not exclusively in men and in hot-humid climates.

<span class="mw-page-title-main">Rosacea</span> Skin condition resulting in redness, pimples and swelling, usually on the face

Rosacea is a long-term skin condition that typically affects the face. It results in redness, pimples, swelling, and small and superficial dilated blood vessels. Often, the nose, cheeks, forehead, and chin are most involved. A red, enlarged nose may occur in severe disease, a condition known as rhinophyma.

<span class="mw-page-title-main">Sweat gland</span> Small sweat-producing tubular skin structures

Sweat glands, also known as sudoriferous or sudoriparous glands, from Latin sudor 'sweat', are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial surface by way of a duct. There are two main types of sweat glands that differ in their structure, function, secretory product, mechanism of excretion, anatomic distribution, and distribution across species:

<span class="mw-page-title-main">Pityriasis rubra pilaris</span> Medical condition

Pityriasis rubra pilaris refers to a group of chronic disorders characterized by reddish orange, scaling plaques and keratotic follicular papules. Symptoms may include reddish-orange patches on the skin, severe flaking, uncomfortable itching, thickening of the skin on the feet and hands, and thickened bumps around hair follicles. For some, early symptoms may also include generalized swelling of the legs, feet and other parts of the body. PRP has a varied clinical progression and a varied rate of improvement. There is currently no known cause or cure for PRP.

<span class="mw-page-title-main">Urushiol-induced contact dermatitis</span> Medical condition

Urushiol-induced contact dermatitis is a type of allergic contact dermatitis caused by the oil urushiol found in various plants, most notably sumac family species of the genus Toxicodendron: poison ivy, poison oak, poison sumac, and the Chinese lacquer tree. The name is derived from the Japanese word for the sap of the Chinese lacquer tree, urushi. Other plants in the sumac family also contain urushiol, as do unrelated plants such as Ginkgo biloba.

<span class="mw-page-title-main">Polymorphous light eruption</span> Medical condition

Polymorphous light eruption (PLE) presents with itchy red small bumps on sun-exposed skin, particularly face, neck, forearms and legs. It generally appears 30 minutes to a few hours after sun exposure and may last between one and 14 days. The bumps may become small blisters or plaques and may appear bloody,often healing with minimal scarring.

<span class="mw-page-title-main">Perioral dermatitis</span> Medical condition

Perioral dermatitis, also known as periorificial dermatitis, is a common type of skin rash. Symptoms include multiple small (1–2 mm) bumps and blisters sometimes with background redness and scale, localized to the skin around the mouth and nostrils. Less commonly the eyes and genitalia may be involved. It can be persistent or recurring and resembles particularly rosacea and to some extent acne and allergic dermatitis. The term "dermatitis" is a misnomer because this is not an eczematous process.

<span class="mw-page-title-main">Allergic contact dermatitis</span> Medical condition

Allergic contact dermatitis (ACD) is a form of contact dermatitis that is the manifestation of an allergic response caused by contact with a substance; the other type being irritant contact dermatitis (ICD).

<span class="mw-page-title-main">Syringoma</span> Medical condition

Syringomas are benign eccrine sweat duct tumors, typically found clustered on eyelids, although they may also be found in the armpits, abdomen, chest, neck, scalp, or groin area, including genitals, in a symmetric pattern. They are skin-colored or yellowish firm, rounded bumps, 1–3 mm in diameter, and may be confused with xanthoma, milia, hidrocystoma, trichoepithelioma, and xanthelasma. They are more common in women and are most commonly found in middle-aged Asian women. While they can present at any time in life, they typically present during adolescence. They are usually not associated with any other symptoms, although can sometimes cause itchiness or irritation.

Fox–Fordyce disease is a chronic blockage of the sweat gland ducts with a secondary, non-bacterial inflammatory response to the secretions and cellular debris in the cysts. The inflammation is often accompanied by intense itching. In general, the disease often causes skin to darken near the affected area and raised bumps or papules to appear. In addition, hair follicles can become damaged which cause hair loss. Hidradenitis is very similar, but tends to have a secondary bacterial infection so that pus-draining sinuses are formed. It is a very devastating skin disease that does not have universally curative treatments.

<span class="mw-page-title-main">Cholinergic urticaria</span> Medical condition

Cholinergic urticaria is a type of hives (urticaria) that is triggered by an increase in body temperature, such as during exercise, sweating, or exposure to heat. It is also sometimes called exercise-induced urticaria or heat hives. The condition is caused by an overreaction of the immune system to the release of histamine and other chemicals in response to the increase in body temperature. This results in the characteristic red, itchy, and sometimes raised bumps or welts on the skin that are associated with hives.

Hypohidrosis is a disorder in which a person exhibits diminished sweating in response to appropriate stimuli. In contrast with hyperhidrosis, which is a socially troubling yet often benign condition, the consequences of untreated hypohidrosis include hyperthermia, heat stroke and death. An extreme case of hypohidrosis in which there is a complete absence of sweating and the skin is dry is termed anhidrosis.

<span class="mw-page-title-main">Heat illness</span> Condition caused by the failure of the human body to dissipate heat in a hot environment

Heat illness is a spectrum of disorders due to increased body temperature. It can be caused by either environmental conditions or by exertion. It includes minor conditions such as heat cramps, heat syncope, and heat exhaustion as well as the more severe condition known as heat stroke. It can affect any or all anatomical systems. Heat illnesses include: heat stroke, heat exhaustion, heat syncope, heat edema, heat cramps, heat rash, heat tetany.

Acne mechanica is an acneiform eruption that has been observed after repetitive physical trauma to the skin such as rubbing, occurring from clothing or sports equipment. In addition to those mechanisms, the skin not getting enough exposure to air also contributes to the formation of acne mechanica. It is often mistaken as a rash that forms on sweaty skin that is constantly being rubbed, but in reality, it is a breakout of acne mechanica. The term "acne" itself describes the occurrence in which hair follicles in the skin get clogged by oil, dead skin cells, dirt and bacteria, or cosmetic products and create a pimple. Pimples can vary in type, size, and shape, but the sole basis of them occurring is the same - the oil gland in the pore becomes clogged and sometimes infected, which creates pus in order to fight the infection and subsequently causes the development of swollen, red lesions on the skin.

<span class="mw-page-title-main">Lymphangioma circumscriptum</span> Medical condition

Superficial lymphatic malformation is a congenital malformation of the superficial lymphatics, presenting as groups of deep-seated, vesicle-like papules resembling frog spawn, at birth or shortly thereafter. Lymphangioma circumscriptum is the most common congenital lymphatic malformation. It is a benign condition and treatment is not required if the person who has it does not have symptoms from it.

<span class="mw-page-title-main">Syringocystadenoma papilliferum</span> Medical condition

Syringocystadenoma papilliferum is a rare non-malignant adnexal neoplasm that develops from apocrine or eccrine sweat glands and can be identified histologically by cystic, papillary, and ductal invaginations into the dermis lined by double-layered outer cuboidal and luminal high columnar epithelium and connected to the epidermis.

A coma blister, or coma bullae, is a skin lesion or blister that typically arises due to pressure in an individual with impaired consciousness. They vary in size, ranging from 4 to 5 centimeters in diameter, and may appear hemorrhagic or blood filled. Coma blisters are usually found in the extremities and trunk. These types of blisters have been associated with the overdose of central nervous system (CNS) depressants especially barbiturates, but also tricyclic antidepressants, hypnotics, benzodiazepines, opiates, antipsychotics, and alcohol. However, studies have found that coma blisters are not caused by the toxicity of these drugs, but due to hypoxia and external pressure on the comatose individual's skin from being immobilized. Coma blisters have been frequently found on individuals who have overdosed on drugs, but have also been found on individuals with chronic kidney failure, hypercalcemia, diabetic ketoacidosis, and a variety of neurologic conditions. Coma blisters are more frequent in adults and less common among children as demonstrated by the few cases published in literature.

References

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