In an immunocompromised patient receiving valacyclovir, how does an open ulcer appear compared with a healing ulcer?

Visual Characteristics of Open vs. Healing Herpes Zoster Ulcers in Immunocompromised Patients

In an immunocompromised patient receiving valacyclovir, an open ulcer appears as a round, weeping lesion with moist, exposed tissue and pronounced surrounding inflammation, while a healing ulcer shows dry crusting, reduced weeping, and progressive epithelialization with subcutaneous fibrosis. 1

Open (Active) Ulcer Characteristics

Active ulcers demonstrate specific features that distinguish them from healing lesions:

• Round, open configuration with approximately 1-inch diameter, actively weeping fluid 1
• Moist, exposed tissue without crust formation, indicating ongoing viral replication 2
• Pronounced subcutaneous fibrosis surrounding the ulcer base, particularly in severe postthrombotic syndrome 1
• Small, round, weeping appearance with active fluid discharge from the lesion surface 1

In immunocompromised patients specifically, open ulcers may present atypically:

• Chronic poorly healing ulcers with persistent viral replication, lacking the typical vesicular component 3
• Loss of vesicular appearance from onset, making lesions appear as chronic ulcers rather than progressing through typical stages 3
• Continued development of new lesions for 7-14 days or longer, compared to 4-6 days in immunocompetent hosts 2, 4, 3
• Higher rates of lesion coalescence and deeper tissue involvement 3

Healing Ulcer Characteristics

Healing ulcers demonstrate progressive resolution with distinct morphologic changes:

• Complete crusting of all lesions, indicating cessation of active viral shedding 2, 4
• Dry, scabbed surface without active weeping or fluid discharge 2
• Pronounced subcutaneous fibrosis with resulting deformity in skin architecture 1
• Progressive reduction in size and inflammation over sequential weeks 1

The healing process follows a predictable timeline:

• Lesions typically crust within 7-10 days in immunocompetent patients receiving appropriate antiviral therapy 2
• Complete healing requires approximately 2 weeks total disease duration in immunocompetent hosts 4, 3
• Immunocompromised patients heal more slowly, potentially requiring extended treatment beyond 7-10 days 2, 5

Critical Clinical Implications for Valacyclovir Treatment

Treatment duration must be guided by lesion appearance, not arbitrary timeframes:

• Continue valacyclovir until all lesions have completely scabbed, which is the key clinical endpoint 2
• Do not discontinue at exactly 7 days if lesions are still forming or have not completely scabbed 2
• Immunocompromised patients may require treatment extension well beyond 7-10 days as their lesions continue to develop over longer periods and heal more slowly 2

Warning signs requiring escalation to intravenous therapy:

• Persistent open, weeping ulcers despite 7-10 days of oral valacyclovir suggest treatment failure or resistance 2
• Development of chronic ulcerations with persistent viral replication indicates need for IV acyclovir 10 mg/kg every 8 hours 2
• Multi-dermatomal involvement or visceral complications require immediate switch to intravenous therapy 2

Common Pitfalls in Assessment

Clinicians frequently underestimate disease severity in immunocompromised patients:

• Atypical lesions lacking characteristic vesicular appearance may lead to underestimation of scarring risk 3
• Assuming 7-day treatment is sufficient when lesions remain open and weeping represents inadequate therapy 2
• Failure to recognize chronic ulceration as a sign of persistent viral replication requiring treatment intensification 2, 3

The patient remains contagious until all lesions are completely crusted over, requiring continued isolation precautions 4