What Causes Vesicular Exanthams?

Patient Presentation
A 3-year-old male came to clinic with a history of fever and developing rash for 24 hours. The fever had been 38.2°C maximum and was responsive to antipyretics. The rash had been noticed during the night and was described as small spots on his arms and trunk. Since then they had developed a central vesicle. All the lesions looked the same, and the mother didn’t think that more were appearing. The family denied any travel. There were sick children at daycare but the family didn’t know what specific problems were occurring. There was no cough, emesis, diarrhea, pain or pruritus. He had rhinorrhea and had been drinking well but was refusing most solids. He was not particularly fatigued, lethargic or irritable. The past medical history showed a healthy child who was fully immunized. The review of systems was otherwise negative.

The pertinent physical exam showed a well-appearing child with a temperature of 38.3°C. Heart rate was 106 beats/minute and respiratory rate was 24/minute. HEENT showed no mucosal involvement, no oral lesions and his tympanic membranes were normal. He had mild clear rhinorrhea. Heart, lungs and abdominal examinations were negative. His skin had ~ 20 lesions that were distinct lesions, scattered on the upper torso and upper arms. They were 4-10 mm in size with a red, blanching base. Most had a central vesicle that was 2-3 mm in size with water-like fluid. All the lesions looked the same. There were no excoriations seen. There were no lesions on the palms or soles.

The diagnosis of a vesicular exanthem was made that was most likely due to a viral etiology such as coxsackie disease. He had a relative who had frequent contact with him and who was immunocompromised. Therefore a lesion was unroofed and a swab was sent for varicella polymerase chain reaction. The patient was started on acyclovir for possible varicella but when the test returned negative the acyclovir was stopped. When the physician contacted the mother the next day, she reported that the lesions had not progressed, his fever was lower and he was drinking well.

Vesicles are circumscribed, elevated, fluid-filled lesions < 1 cm on the skin. They contain serious exudates or a mixture of blood and serum. They last for a short time and either break spontaneously or evolve into bullae. They can be discrete (e.g. varicella or rickettsial disease), grouped (e.g. herpes), linear (e.g. rhus dermatitis) or irregular (e.g. coxsackie) in distribution.

Associated symptoms such as pruritus, fever, myalgias, coryza and cough, along with a history of potential contact can be helpful. Vesicular rashes that are associated with systemic findings such as fever are usually due to infectious diseases (especially viruses and bacteria), while those that do not have systemic findings often are due to contact or infectious diseases that are non-respiratory contacts such as scabies or tinea.

Most patients do not need specific testing as the clinical history and physical examination will often be enough. In certain cases, scraping of the lesion to look for parasites (i.e. scabies) or multinucleated giant cells (i.e. herpes) or fungus may be indicated.

Most treatment is supportive. Topical agents such as calamine lotion or oatmeal baths may provide some relief. Medication for pain and pruritus can be helpful. Treatment for specific diseases such as acyclovir for herpes, antibiotics for bacterial disease and antifungal mediation for fungal diseases should be recommended as appropriate.

Bullae are also fluid-filled epidermal lesions that are filled with serous or seropurulent fluid. They are > 1 cm and often easily rupture due to their thin walls. The differential diagnosis is different for bullae than for vesicular lesions and is often more ominous including such diseases as Steven-Johnson, staphylococcal scalded skin and meningococcemia.

Vesicular or bullous exanthems should be investigated more extensively if there is skin sloughing, petechiae or purpura, fever and irritability, inflammation of the mucosa, urticaria, has respiratory distress, and diarrhea or abdominal pain.

Learning Point
The differential diagnosis for vesicular exanthems includes:

  • Viral
    • Coxsackie
    • Echo
    • Herpes
    • Smallpox
    • Varicella
  • Bacteria
    • Haemophilus
    • Staphylococcus
    • Streptococcus
    • Mycoplasma
  • Fungal
    • Trichophyton mentagrophytes
    • Tricophyton rubrum
  • Parasitic
    • Rickettsial diseases
    • Scabies
    • Tularemia
  • Other
    • Contact and Rhus dermatitis
    • Dishidrotic eczema
    • Kawasaki disease
    • Photosensitivity

Questions for Further Discussion
1. What is the differential diagnosis of bullous exanthems?
2. What is the difference between a pustular lesion and those that are vesicular or bullous?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com, the National Guideline Clearinghouse and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for this topic: Rash.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Sifuentes M. Vesicular Exanthems, in Pediatrics A Primary Care Approach. Berkowitz CD ed. W.B. Saudners and Co. Philadelphia, PA. 1996;400-403.

Feder HM Jr, Bennett N, Modlin JF. Atypical hand, foot, and mouth disease: a vesiculobullous eruption caused by Coxsackie virus A6. Lancet Infect Dis. 2014 Jan;14(1):83-6.

Barr KL. Evaluation of vesicular-bullous rash. ePocrates.
Available from the Internet at https://online.epocrates.com/u/2911775/Evaluation+of+vesicular-bullous+rash/Differential/Overview (rev. 10/3/14, cited 1/27/15).


Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital