A 30-year-old woman has repeated episodes of target-shaped lesions on the palms and forearms, each episode preceded 1 to 2 weeks earlier by a brief cold sore. Prophylactic continuous oral acyclovir is recommended for her because it:

• A Directly inhibits immune complex deposition in the dermal vessels
• B Suppresses HSV reactivation that acts as the trigger for recurrent erythema multiforme ✓
• C Prevents mycoplasmal superinfection of the upper respiratory tract
• D Blocks TNF-alpha release from keratinocytes in the target lesions

Explanation

Recurrent herpes-associated erythema multiforme (HAEM) is driven by HSV DNA fragments reaching the skin and triggering a delayed-type hypersensitivity reaction via CD4 T cells. Continuous suppressive acyclovir prevents HSV reactivation and thereby reduces HAEM episodes; trials show clear benefit when episodes follow documented herpes labialis. Mycoplasma triggers single episodes rather than recurrences tied to cold sores, and acyclovir has no immunosuppressive action on complexes or TNF-alpha.

Reference: Fitzpatrick's Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.