Miliaria


Article Author:
Karla Guerra


Article Editor:
Karthik Krishnamurthy


Editors In Chief:
David Wood
Andrew Wilt
Hajira Basit


Managing Editors:
Avais Raja
Orawan Chaigasame
Khalid Alsayouri
Kyle Blair
Radia Jamil
Erin Hughes
Patrick Le
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Hassam Zulfiqar
Navid Mahabadi
Hussain Sajjad
Steve Bhimji
Muhammad Hashmi
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Abbey Smiley
Sarosh Vaqar
Mark Pellegrini
James Hughes
Beenish Sohail
Hajira Basit
Phillip Hynes
Sandeep Sekhon


Updated:
12/26/2018 3:43:41 PM

Introduction

Miliaria, or eccrine miliaria, is a frequently seen skin disease triggered by blocked eccrine sweat glands and ducts, causing backflow of eccrine sweat into the dermis or epidermis.[1] This backflow results in a rash comprising sweat-filled vesicle formation under the skin. Other names for it include “heat rash,” “prickly heat,” or a “sweat rash.”[2] It is most common in warm, humid climates during the summer months. The 3 main types of miliaria are crystallina, rubra, and profunda and are classified by the depth of obstruction of the sweat duct causing clinical and histological differences. The rash is usually self-limited and resolves independently of treatment.

Etiology

Though miliaria affects all age groups and both genders equally, infants and children are at a higher risk due to eccrine duct immaturity.[3] Sweating is the most common risk factor for miliaria. Therefore, hot or humid conditions and high fevers are associated with miliaria. The following have been identified as causes of miliaria:

  • Occlusion of the skin: Transdermal drug patches and tight clothing have been associated with miliaria.[4][5]
  • Type I pseudohypoaldosteronism: Mineralocorticoid resistance results in loss of sodium through eccrine glands and has been associated with pustular miliaria rubra.[6][7][8]
  • Strenuous physical activity
  • Morvan syndrome: A rare autosomal recessive disease that results in hyperhidrosis, among other abnormalities, which predisposes to miliaria.[9][10]
  • Medications: Drugs that induce sweating such as bethanechol, clonidine, and neostigmine have been linked to miliaria.[11] Additionally, few cases of isotretinoin-induced miliaria have been reported.[12]

Epidemiology

Miliaria frequently affects neonates and those individuals suffering from increased sweating and living in hot and humid climates. Though seen in all races and both genders, each type of miliaria affects a slightly different population.

Miliaria crystallina, or sudamina, commonly affects neonates with the greatest incidence at 2 weeks of age or less. It affects between 4.5% to 9% of neonates.[13][14] It can also be seen in adults who have recently relocated to a warmer climate.

Miliaria rubra, the most common form of miliaria, is frequently seen in neonates between 1 and 3 weeks of age and can affect up to 30% of adults living in hot and humid conditions.[3]

Miliaria profunda is the rarest form of miliaria and is most commonly seen in people who have recurrent episodes of miliaria rubra or individuals exposed to new warm climates such as military persons deployed in tropical climates.[15]

Pathophysiology

The main cause of miliaria is obstruction of the eccrine sweat duct. This can be due to cutaneous debris or bacteria like Staphylococcus epidermidis which form biofilms.[16][17] This leads to leakage of sweat back into the epidermis or dermis, resulting in cellular overhydration and swelling which further occludes the duct. More profound involvement of the eccrine gland or duct may lead to rupture. The different types of miliaria have different cutaneous involvement, with miliaria crystallina occurring due to ductal occlusion of the stratum corneum, miliaria rubra occurring due to ductal occlusion in the epidermis at the subcorneal layers, and miliaria profunda resulting from a ductal occlusion in the dermal-epidermal junction, specifically the papillary dermis.

Histopathology

The histology of miliaria is different based on the type, as each different type is classified by the depth of obstruction of the eccrine duct. Miliaria crystallina usually displays subcorneal or intracorneal vesicles of the intraepidermal part of the duct that may contain neutrophils. Miliaria rubra displays epidermal spongiosis with parakeratosis and vesicles in the epidermis communicating with the eccrine duct. There may be inflammatory lymphocytic infiltrate surrounding the duct and superficial vasculature. Miliaria profunda displays intradermal spongiosis of the eccrine duct, and is comparable to miliaria rubra, though shows rupture of the eccrine duct and more significant lymphocytic inflammation. It is PAS-positive, diastase-resistant.

History and Physical

Miliaria is a disorder involving vesicles, papules, and pustules of the skin. It is crucial to take a closer look at the skin and location of the rash in to characterize the rash and arrive at an accurate diagnosis.

Miliaria crystallina shows up as 1- to 2-mm superficial vesicles, affecting both adults and neonates usually younger than 2 weeks old. Because the pathophysiology involves the stratum corneum or the most superficial layer of the outer layer of the skin, the vesicles have a thin superficial layer that results in the vesicles resembling water droplets on the skin that easily rupture.[11] The vesicles are superficial; therefore, an inflammatory response is typically absent. The upper trunk, neck, and head are the most commonly affected sites. The blisters will usually appear within a few days of exposure to risk factors and will resolve within a day after the superficial layer of skin rubs off.[18]

Miliaria rubra is the most prevalent form of miliaria, and due to obstruction of eccrine ducts in the deeper layers of the skin, an inflammatory response is witnessed. This results in larger, erythematous papules and vesicles. One of the critical clinical diagnostic features is the minimal follicular involvement, which helps differentiate miliaria rubra from folliculitis. If pustules are present, then miliaria rubra is called miliaria pustulosa and may indicate a bacterial infection. Because an inflammatory response is involved, patients may experience pruritic and painful symptoms, which may worsen during perspiration. In neonates usually between the ages 1 to 3 weeks, the groin, axilla, and neck are the most commonly affected areas. In adults, miliaria rubra is most likely seen in places where clothes rub on the skin such as the trunk and extremities. The face is usually spared. Superinfection with staphylococci may occur, and when impetigo or multiple abscesses are involved, the condition is called periporitis staphylogenes.[19] 

Miliaria profunda, due to a deeper involvement of the skin at the dermal-epidermal junction, results in firm, large, flesh-colored papules that are also not centered around a follicle. The eruption can be asymptomatic but may also be extremely pruritic. It is usually seen in patients with numerous previous episodes of miliaria rubra. The most common location involved in adults is the trunk, but the arms and legs may also be involved. The skin rash usually appears within minutes to hours of perspiration and resolves within an hour of sweating cessation.

In both miliaria rubra and miliaria profunda, anhidrosis may occur in affected areas due to obstructed sweat glands. As such, heat exhaustion may occur due to ineffective thermoregulation in patients with largely affected areas and should be considered in the setting of a skin rash accompanied by hyperthermia.

Evaluation

Miliaria is a clinical diagnosis. Laboratory tests are often inconclusive and not helpful. Dermoscopy has been found to be a useful tool, particularly in people with darker skin, revealing large white globules with surrounding darker halos (white bullseye).[20] When in doubt, a skin punch biopsy would be useful to help with diagnosis. Please refer above to the histopathology section regarding findings. High-definition optical coherence tomography has assisted in finding the obstruction of the eccrine duct.[21]

Treatment / Management

Because hot, sweaty conditions are the main risk factors for miliaria, general measures to decrease sweating and eccrine duct blockage are warranted in the management of miliaria. This includes cooler environments, wearing breathable clothes, exfoliating the skin, removing skin occluding objects such as band-aids or patches, and treating febrile illnesses.

Specific modalities for treatment of miliaria are unique depending on the type. Miliaria crystallina is usually not treated as it is self-limited and usually resolves within 24 hours. Miliaria rubra treatment is geared towards decreasing inflammation, and therefore mild to mid-potency corticosteroids like triamcinolone 0.1% cream may be applied for one to two weeks. If miliaria pustulosa develops, topical antibiotics such as clindamycin are indicated.

Very little information exists regarding the treatment of miliaria profunda except the general measures listed above. However, results in one study showed improvement of 1 patient with miliaria profunda with the combined use of oral isotretinoin 40 mg per day for 2 months and topical anhydrous lanolin.[22]

Differential Diagnosis

  • Viral exanthems or viral infections such as herpes simplex or varicella
  • Cutaneous candidiasis or other fungal skin infections
  • Folliculitis, whether bacterial or pityrosporum
  • Neonatal acne or erythema toxicum neonatorum
  • Drug rashes, particularly acute, generalized, exanthematous pustulosis
  • Grover disease
  • Arthropod bites
  • Lymphocytoma cutis or cutaneous T-cell pseudolymphomas

Prognosis

Most cases of miliaria resolve spontaneously after decreasing risk factors and moving to a cooler environment.

Complications

The most serious complication that may result from miliaria is anhidrosis, leading to poor thermoregulation and heat exhaustion. This may permanently disable a person from work or prevent an active person from continuing exercise or sports. Bacterial superinfections may occur due to the epidermal layer being affected.

Deterrence and Patient Education

Physicians should educate patients about the causes of miliaria, including hot, humid climates, and non-breathable clothes. If a patient is predisposed to miliaria, the clinician should create a personalized plan should for the patient that includes methods of avoiding overheating, which clothes are most appropriate, and how to react when the rash appears. Clinicians should also educate patients on the signs and symptoms of heat exhaustion if they develop anhidrosis secondary to miliaria.

Enhancing Healthcare Team Outcomes

Miliaria is a generally benign skin disorder that occurs in patients of all ages and genders who are exposed to humid, warm climates. It is usually self-limited and resolves spontaneously in response to a cooler, dryer atmosphere. In situations where a rash appearing to be miliaria does not resolve quickly, a consultation with a dermatologist should rule out other more serious rashes that may mimic miliaria.


  • Image 312 Not availableImage 312 Not available
    Contributed by DermNetNZ
Attributed To: Contributed by DermNetNZ

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Miliaria - Questions

Take a quiz of the questions on this article.

Take Quiz
During rounds at the hospital, a 72-hour-old newborn is noted to have a rash on their face and neck that appears as easily ruptured vesicles with a slightly erythematous base. The neonate has been bundled up with blankets, as it is cold in the hospital room. What is the most likely diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following assists in making the diagnosis of miliaria rubra?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following does not increase the risk of developing miliaria?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which form of miliaria is due to obstruction of eccrine ducts in the deeper layers of the epidermis with minimal dermal involvement?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is correct regarding the treatment of miliaria?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Miliaria - References

References

Wenzel FG,Horn TD, Nonneoplastic disorders of the eccrine glands. Journal of the American Academy of Dermatology. 1998 Jan     [PubMed]
El Anzi O,Hassam B, [Widespread miliaria crystallina: about a case]. The Pan African medical journal. 2018     [PubMed]
LYONS RE,LEVINE R,AULD D, Miliaria rubra, a manifestation of staphylococcal disease. Archives of dermatology. 1962 Sep     [PubMed]
Ale I,Lachapelle JM,Maibach HI, Skin tolerability associated with transdermal drug delivery systems: an overview. Advances in therapy. 2009 Oct     [PubMed]
Carter R 3rd,Garcia AM,Souhan BE, Patients presenting with miliaria while wearing flame resistant clothing in high ambient temperatures: a case series. Journal of medical case reports. 2011 Sep 22     [PubMed]
Onal H,Adal E,Ersen A,Onal Z,Keskindemirci G, Miliaria rubra and thrombocytosis in pseudohypoaldosteronism: case report. Platelets. 2012     [PubMed]
Urbatsch A,Paller AS, Pustular miliaria rubra: a specific cutaneous finding of type I pseudohypoaldosteronism. Pediatric dermatology. 2002 Jul-Aug     [PubMed]
Akcakus M,Koklu E,Poyrazoglu H,Kurtoglu S, Newborn with pseudohypoaldosteronism and miliaria rubra. International journal of dermatology. 2006 Dec     [PubMed]
Tabanelli M,Passarini B,Liguori R,Balestri R,Gaspari V,Giacomini F,Patrizi A, Erythematous papules on the parasternal region in a 76-year-old man. Clinical and experimental dermatology. 2008 May     [PubMed]
Abou-Zeid E,Boursoulian LJ,Metzer WS,Gundogdu B, Morvan syndrome: a case report and review of the literature. Journal of clinical neuromuscular disease. 2012 Jun     [PubMed]
Haas N,Martens F,Henz BM, Miliaria crystallina in an intensive care setting. Clinical and experimental dermatology. 2004 Jan     [PubMed]
Gupta AK,Ellis CN,Madison KC,Voorhees JJ, Miliaria crystallina occurring in a patient treated with isotretinoin. Cutis. 1986 Oct     [PubMed]
Hidano A,Purwoko R,Jitsukawa K, Statistical survey of skin changes in Japanese neonates. Pediatric dermatology. 1986 Feb     [PubMed]
Goyal T,Varshney A,Bakshi SK, Incidence of Vesicobullous and Erosive Disorders of Neonates: Where and How Much to Worry? Indian journal of pediatrics. 2011 Oct 25     [PubMed]
SANDERSON PH,SLOPER JC, Skin disease in the British army in S. E. Asia. I. Influence of the environment on skin disease. The British journal of dermatology. 1953 Jul-Aug     [PubMed]
Mowad CM,McGinley KJ,Foglia A,Leyden JJ, The role of extracellular polysaccharide substance produced by Staphylococcus epidermidis in miliaria. Journal of the American Academy of Dermatology. 1995 Nov     [PubMed]
Kravvas G,Veitch D,Al-Niaimi F, The increasing relevance of biofilms in common dermatological conditions. The Journal of dermatological treatment. 2018 Mar     [PubMed]
Dixit S,Jain A,Datar S,Khurana VK, Congenital miliaria crystallina - A diagnostic dilemma. Medical journal, Armed Forces India. 2012 Oct     [PubMed]
LUBOWE II,PERLMAN HH, Periporitis staphylogenes and other complications of miliaria in infants and children. A.M.A. archives of dermatology and syphilology. 1954 May     [PubMed]
Mohanan S,Behera B,Chandrashekar L,Kar R,Thappa DM, Bull's-eye pattern in miliaria rubra. The Australasian journal of dermatology. 2014 Nov     [PubMed]
Tey HL,Tay EY,Cao T, In vivo imaging of miliaria profunda using high-definition optical coherence tomography: diagnosis, pathogenesis, and treatment. JAMA dermatology. 2015 Mar     [PubMed]
Kirk JF,Wilson BB,Chun W,Cooper PH, Miliaria profunda. Journal of the American Academy of Dermatology. 1996 Nov     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Pediatrics-Medical Student. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Pediatrics-Medical Student, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Pediatrics-Medical Student, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Pediatrics-Medical Student. When it is time for the Pediatrics-Medical Student board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Pediatrics-Medical Student.