Characterizing Viral Exanthems

Abstract and Introduction

Abstract

An exanthem is any eruptive skin rash that may be associated with fever or other systemic symptoms. Causes include infectious pathogens, medication reactions and, occasionally, a combination of both. In children, exanthems are most often related to infection and, of these, viral infections are the most common. Some exanthems have very specific morphologies that help identify and characterize the eruption. In this article, we describe common and uncommon viral exanthems, based on their morphology, and review current advancements in understanding and treatment of these exanthems.

Introduction

An exanthem is any eruptive skin rash that may be associated with fever or other systemic symptoms. Causes include infectious pathogens, medication reactions and, occasionally, a combination of both.

Over 100 years ago, a group of characteristic childhood eruptions were described and numbered from one to six:^[1,2] measles, scarlet fever, rubella, erythema infectiosum and roseola infantum. The origin of the fourth classic childhood eruption, formerly referred to as Dukes' disease, is controversial. It may represent misdiagnosed cases of rubella or scarlet fever, rather than a distinct illness.

Viral exanthems are common in childhood. The words 'exanthema' and 'anthos' mean 'breaking out' and 'flower' in Greek, respectively. Similarly, a child breaking out with a viral exanthem may be likened to a flower bursting into bloom. In children, exanthems are most often related to infection^[3] and, of these, viral infections are the most common. Determining the cause of an exanthem is based on the characteristic morphology, distribution and time course of the eruption, as well as a careful assessment of infectious contacts, immunization status and aspects of the physical examination. Although not always diagnostic, the morphology and configuration of cutaneous lesions are of considerable importance to the classification and diagnosis of viral exanthems. For the purpose of this article, we will characterize common and uncommon viral exanthems, based on their morphology, and will discuss current advancements in understanding and treatment of these viral diseases.

Cite this: Characterizing Viral Exanthems - Medscape - Dec 01, 2010.

Box 1. Proposed diagnostic criteria for papular acrodermatitis of childhood.
*Positive clinical features* Monomorphous, flat-topped, pink-brown papules or papulovesicles 1–10 mm in diameter on at least three of the following four sites: cheeks, buttocks, extensor surfaces of the forearms, and extensor surfaces of the legs Symmetrical distribution Duration of at least 10 days
*Negative clinical features* Extensive truncal lesions Scaly lesions

Data taken from [52].

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Executive Summary

Macular & maculopapular exanthems

Measles, rubella, erythema infectiousum and roseola infantum are part of the six classic childhood exanthems, and have very distinct and recognizable features.
The eruption when aminopenicillins are administered to patients with Epstein–Barr virus is a bright-red morbilliform eruption that does not preclude future use of aminopenicillins.

Vesicular & pustular exanthems

Varicella infection is benign and self-limiting, but has the potential to cause life- and limb-threatening complications in immunocompetent and immunocompromised hosts. The varicella vaccine is now available in combination with the measles–mumps–rubella vaccine.
Eczema herpeticum is a severe form of disseminated cutaneous herpes simplex virus infection that morphologically presents as monomorphic umbilicated vesiclulopustules, which progress to form punched-out erosions.
Hand–foot–mouth disease is a distinct monomorphous exanthem that is most commonly caused by the Coxsackie A16 virus and human enterovirus 71. Meningoencephalitis and myocarditis are rare complications, which occur more commonly with human enterovirus 71.
Although acute generalized exanthematous pustulosis usually occurs following drug ingestion, cases in children may be caused by viral infections.

Papular exanthems

Papular acrodermatitis of childhood is characterized by the abrupt onset of erythematous papules over the extremities, buttocks and face, with relative sparing of the abdomen and chest. It appears to occur as a response to a number of infectious stimuli.
Therapy for molluscum contagiosum ranges from destructive techniques to observation, as lesions will eventually resolve spontaneously.

Other viral exanthems

Parovovirus B19 has been linked recently to several petechial and purpuric exanthems, which may be localized to particular areas of the body. Recently, it has also been implicated in outbreaks of generalized petechiae.
Pityriasis rosea in children may present atypically by involving the face and extremities.
Erythema multiforme is often triggered by herpes simplex virus in children.
Unilateral laterothoracic exanthem is a distinct exanthem, which preferentially affects one side of the body, with a prolonged clinical course.

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