From the Guidelines
A viral exanthem, such as the one caused by Varicella-Zoster Virus (VZV), typically presents as a unilateral, vesicular eruption with dermatomal pain that often precedes the skin findings by 24–72 hours. The rash usually starts as erythematous macules that rapidly evolve to papules and then to vesicles, which frequently coalesce, form bullae, and scab before healing 1. In immunocompromised hosts, the rash may continue to develop over a longer period and generally heals more slowly unless effective antiviral therapy is administered 1. Some key characteristics of the rash include:
- Initial lesions are erythematous macules that rapidly evolve to papules and then to vesicles
- Vesicles frequently coalesce, form bullae, and scab before healing
- Lesions in otherwise healthy hosts continue to erupt for at least 4–6 days, with the entire disease duration being approximately 2 weeks
- In immunocompromised hosts, skin lesions may continue to develop over a longer period (7–14 days) and generally heal more slowly unless effective antiviral therapy is administered 1. It's worth noting that the rash can be atypical, localized, faint, or evanescent, and skin pigmentation might make the rash difficult to recognize, as seen in other infectious diseases 1. However, the specific characteristics of the VZV rash, as described in the study by Stevens et al. 1, are the most relevant to this question. The most important consideration in managing a viral exanthem is to provide symptom management and prevent complications, particularly in immunocompromised hosts.
From the Research
Characteristics of Viral Exanthem Rash
- The rash of a viral exanthem can present with diverse morphologies, including:
- Macular
- Maculopapular
- Papular
- Urticarial
- Vesicular
- A combination of these 2
- The distribution and morphology of the rash, as well as geographic location and potential exposure to vector-borne or blood-borne viruses, can provide important clues to the diagnosis of viral exanthems 3
Diagnostic Challenges
- Determining the viral cause of a rash presents significant diagnostic challenges 3
- Clinical, hematological, and biochemical investigations are seldom reliable in distinguishing between a drug reaction and a viral exanthem 4
- Histopathological and immunohistochemical evaluations may help in distinguishing between drug-induced and viral etiologies when faced with a clinical overlap 4
Clinical Variations
- Certain viral exanthems, such as coronavirus disease 2019, chikungunya, hand-foot-and-mouth disease, and mpox, can present with atypical presentations, including an increased frequency of affliction across broader age groups and heightened manifestations often posing as 'great imitators' mimicking a myriad of other dermatoses 2
- Climate change, global warming, and spillover of zoonotic viruses are contributing to the emergence and spread of viral diseases, leading to changing disease dynamics and clinical variations in presentations 2, 3