Superficial Ulceration on the Vulva

Foscarnet-Induced Ulceration

Viral swabs were negative for herpes simplex virus. The diagnosis of foscarnet-induced ulceration was reached and the drug was discontinued. Symptomatic treatment with soap substitutes and lidocaine ointment was used.

Foscarnet is an antiviral agent used when resistance develops to first-line therapies.¹ It is a pyrophosphate analogue that inhibits viral DNA polymerase, thereby preventing viral replication. It is used in treating cytomegalovirus and herpes simplex virus, which are resistant to first-line therapies, or patients who develop hematologic toxicity from antivirals. The main side effects of foscarnet include nephrotoxicity, alteration of calcium homeostasis, and malaise. Genital ulceration is a known side effect of therapy, though it is rare and more commonly seen in uncircumcised males. Approximately 94% of the drug is excreted unchanged in the urine, which causes an irritant dermatitis that is more pronounced in males as the urine stays in the subpreputial area.¹

Vulval ulceration² and penile ulceration³ has been reported in AIDS patients treated with foscarnet. In these patients, the onset of ulceration is temporally related to foscarnet therapy, occurring at approximately day 7 to 24 of treatment and resolving after discontinuation of therapy.