What lesions have a similar morphology to herpes zoster?

Lesions with Similar Morphology to Herpes Zoster

Herpes simplex virus (HSV) infections present with the most similar morphology to herpes zoster, particularly in immunocompromised patients where both conditions can manifest as vesicular eruptions that evolve into ulcerations, making clinical differentiation challenging without laboratory confirmation.

Primary Differential: Herpes Simplex Virus

Morphologic Similarities

• HSV lesions progress through identical stages: erythematous macules → papules → vesicles → pustules → ulcers, exactly mirroring the evolution of herpes zoster lesions 1
• 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 1

Key Distinguishing Features

• Distribution pattern: HSV typically lacks the unilateral dermatomal distribution that characterizes herpes zoster 1, 2
• Prodromal pain: The 24-72 hour dermatomal pain preceding skin findings is characteristic of zoster but not HSV 1, 2
• Laboratory confirmation is essential in immunocompromised patients where morphology alone cannot reliably distinguish between HSV and VZV 1

Other Conditions with Overlapping Features

Disseminated Varicella

• Some patients with herpes zoster present initially with disseminated cutaneous infection that mimics atypical varicella rather than typical dermatomal zoster 1
• This presentation can occur in immunocompromised hosts and may not initially display the characteristic vesicular appearance 1

Atypical Presentations in Immunocompromised Patients

• Disseminated ecthymatous lesions from VZV can present without a vesicular stage, appearing as persistent ulcerative lesions that mimic other conditions 3
• In profoundly immunocompromised patients (CD4+ <100 cells/µL), extensive, deep, nonhealing ulcerations from either HSV or VZV can be morphologically indistinguishable 1

Critical Clinical Pitfalls

When Clinical Diagnosis Fails

• Laboratory confirmation should be pursued in all cases where there is diagnostic uncertainty, especially in immunocompromised patients 1
• Available diagnostic methods include viral culture, HSV/VZV DNA PCR (most sensitive), and antigen detection 1
• Tzanck smear showing giant cells can confirm herpesvirus infection but cannot distinguish between HSV and VZV 2

Special Considerations

• Secondary bacterial and fungal superinfections can complicate both HSV and VZV ulcerations in immunocompromised hosts, further obscuring the underlying viral etiology 1, 4
• Nonspecific lesions that lack typical vesicular morphology may represent either HSV or VZV in immunosuppressed patients 1, 2
• The profound loss of T cell function in AIDS can lead to atypical morphology and prolonged course for both herpesvirus infections 3