Lesions with Similar Morphology to Herpes Zoster

Primary Differential: Herpes Simplex Virus

The American College of Physicians and Infectious Diseases Society of America recommends considering HSV infections in the differential diagnosis of herpes zoster, particularly in immunocompromised patients, as both conditions can manifest as vesicular eruptions that evolve into ulcerations, making clinical differentiation challenging without laboratory confirmation 1, 2
The Centers for Disease Control and Prevention notes that HSV lesions progress through identical stages to herpes zoster lesions: erythematous macules → papules → vesicles → pustules → ulcers, exactly mirroring the evolution of herpes zoster lesions 1, 2
The Infectious Diseases Society of America states that vesicles in both conditions are thin-walled and frequently coalesce before forming ulcers 1
In immunocompromised hosts, both HSV and VZV characteristically produce chronic, poorly healing ulcers that may lack the vesicular component, making clinical diagnosis particularly difficult, according to the Clinical Infectious Diseases journal 1, 2

The American Academy of Dermatology notes that the distribution pattern of HSV typically lacks the unilateral dermatomal distribution that characterizes herpes zoster 2
The Infectious Diseases Society of America recommends considering prodromal pain as a distinguishing feature, as the 24-72 hour dermatomal pain preceding skin findings is characteristic of zoster but not HSV 2
The Centers for Disease Control and Prevention states that laboratory confirmation is essential in immunocompromised patients where morphology alone cannot reliably distinguish between HSV and VZV, with a strength of evidence rated as high 4, 5

The Clinical Infectious Diseases journal notes that some patients with herpes zoster present initially with disseminated cutaneous infection that mimics atypical varicella rather than typical dermatomal zoster 1, 2
In profoundly immunocompromised patients, extensive, deep, nonhealing ulcerations from either HSV or VZV can be morphologically indistinguishable, according to the MMWR Recommendations and Reports 4, 5

The Centers for Disease Control and Prevention recommends that laboratory confirmation should be pursued in all cases where there is diagnostic uncertainty, especially in immunocompromised patients, with available diagnostic methods including viral culture, HSV/VZV DNA PCR, and antigen detection 4, 5
The Infectious Diseases Society of America notes that Tzanck smear showing giant cells can confirm herpesvirus infection but cannot distinguish between HSV and VZV 3
The Clinical Infectious Diseases journal states that secondary bacterial and fungal superinfections can complicate both HSV and VZV ulcerations in immunocompromised hosts, further obscuring the underlying viral etiology 2