This conference follows a post-allogeneic stem cell transplant patient with a complex rash history: diffuse pruritic dermatitis, cutaneous/GI GVHD, multiple prophylactic antimicrobials, and a progressive ulcerative lip lesion initially treated as HSV despite oral acyclovir exposure. The case highlights the diagnostic uncertainty created by overlapping GVHD, drug eruption, viral infection, and malignancy-related skin disease in a severely immunocompromised host.
The teaching portion emphasizes how to approach rash “decision points”: when to biopsy, when to send PCR versus culture, why susceptibility testing logistics matter, and how renal function can limit IV antiviral choices. The final diagnosis of HSV-2 herpes folliculitis and the eventual use of topical cidofovir frame a practical discussion of suspected acyclovir-resistant HSV and diagnostic delays.