A 73-year-old woman presents with itching of the lower back, buttocks, and eyes, without blisters, hives, or other symptoms, and has no history of chickenpox or shingles vaccination. What is the next step in management?

Evaluation for Shingles Without Rash (Zoster Sine Herpete)

This patient requires immediate clinical evaluation for zoster sine herpete (ZSH), a condition where varicella-zoster virus reactivates without producing the characteristic rash, particularly given her lack of chickenpox history and no prior vaccination, making her susceptible to VZV infection.

Clinical Assessment Priority

The combination of dermatomal itching (lower back and buttocks) with eye involvement in an elderly, unvaccinated patient with no chickenpox history raises significant concern for atypical VZV reactivation. While classic shingles presents with vesicular rash, ZSH can manifest with pain, itching, or other neurological symptoms in a dermatomal distribution without visible skin lesions 1, 2.

Key Diagnostic Steps

Immediate evaluation should focus on:

• Dermatomal pattern assessment: Carefully map whether the itching follows a specific dermatome (e.g., L1-L3 for lower back/buttocks). The involvement of eyes suggests possible trigeminal nerve involvement, which would be concerning for ophthalmic zoster
• Neurological examination: Assess for any sensory changes, weakness, or cranial nerve deficits
• Ophthalmologic evaluation: Eye itching in this context warrants urgent ophthalmology consultation to rule out herpes zoster ophthalmicus, which can cause vision loss even without visible rash

Diagnostic Testing

If clinical suspicion for ZSH is moderate to high:

• VZV serology: Check VZV IgG and IgM. Positive IgM or rising IgG titers support recent reactivation 2
• VZV PCR: If symptoms are severe or neurological complications suspected, consider PCR testing of appropriate specimens (CSF if meningitis/encephalitis suspected) 1
• Skin examination: Continue monitoring for delayed rash appearance, as vesicles may develop days after symptom onset

Treatment Considerations

If ZSH is diagnosed or highly suspected clinically:

Given the patient's age (73 years) and risk for complications, empiric antiviral therapy should be strongly considered while awaiting confirmatory testing, particularly if ophthalmic involvement is present. Standard treatment would be:

• Famciclovir 500 mg three times daily for 7-10 days, OR
• Valacyclovir 1 g three times daily for 7-10 days, OR
• Acyclovir 800 mg five times daily for 7-10 days

These are the modern equivalents to the older acyclovir regimens mentioned in the guidelines 3, with better bioavailability.

Alternative Diagnoses to Consider

If VZV testing is negative, evaluate for:

• Neuropathic itch: Can present with dermatomal distribution without rash
• Contact dermatitis: Though typically would show skin changes
• Systemic causes of pruritus: Given the generalized nature (back, buttocks, eyes), consider checking complete blood count, liver function, renal function, and thyroid function to rule out systemic causes 4
• Allergic conjunctivitis: For the eye symptoms specifically

Critical Pitfalls to Avoid

1. Don't dismiss symptoms due to absence of rash: ZSH is frequently missed because clinicians expect visible lesions 2
2. Don't delay ophthalmic referral: Herpes zoster ophthalmicus can cause permanent vision loss and requires urgent treatment 5
3. Don't assume negative chickenpox history means no VZV exposure: Up to 90% of adults are seropositive for VZV even without recalled chickenpox history 6
4. Don't wait for rash to develop before treating: If clinical suspicion is high and especially with eye involvement, empiric antiviral therapy is warranted to prevent complications

Vaccination Consideration

After acute management, this patient should receive the recombinant zoster vaccine (Shingrix) once recovered, as she remains at high risk for future VZV reactivation given her age and lack of prior immunity.