Vulvar vitiligo-like depigmentation and multiple halos of hypomelanosis at the trunk following treatment with imiquimod 5% cream for vulvar condylomata: casual or related events?

Abstract

A 25-year-old Caucasian female with multiple genital warts involving the vulvar area was treated with imiquimod 5% cream. During follow-up the patient developed areas of hypopigmentation at the site of application of imiquimod cream and areas of hypomelanosis around multiple preexisting nevi of the trunk. At 18 months follow-up genital depigmentation persisted and halo nevi of the trunk were still present. Different mechanisms of imiquimod-induced depigmentation have been reported. Halo nevi are considered expression of an autoimmune response. In the case presented here, it might be conceivable that both vitiligo-like depigmentation at the site of application and halo of hypomelanosis around melanocytic nevi have been induced by the same immunologic mechanism elicited by topical application of imiquimod.

Vitiligo-Like Depigmentation following Treatment with Imiquimod 5% Cream for Condylomata Acuminata

“…In the literature, imiquimod application has been reported to cause depigmentation via different mechanisms of action, including postinflammatory depigmentation, necrosis or apoptosis of melanocytes, and immune-mediated vitiligo-like reactions [ 5 ]. One reason for the presence of those depigmented lesions after topical imiquimod application is that the cream could induce local melanocyte apoptosis [ 12 ], which was observed by TUNEL assay, by Hoechst 33258 staining, and by measuring mitochondrial membrane potential in melanocytes [ 8 ].…”

“…Imiquimod (Aldara®) (2.5, 3.75, and 5%) is a commercially available topical cream. It is currently approved by the US Food and Drug Administration (FDA) for use as a topical treatment for biopsy-confirmed small superficial basal cell carcinoma measuring up to 2 cm in its greatest diameter over the neck, trunk, or extremities (excluding the hands and feet) [ 1 ], nonhyperkeratotic nonhypertrophic actinic keratoses over the face and/or scalp [ 2 , 3 ], and external genital and perianal warts (condylomata acuminata) in adults [ 4 , 5 ]. In condylomata acuminata, which is considered to be a sexually transmitted disease, it is approved to be used as a 5% cream three times weekly for up to 16 weeks, or as a 3.75% cream daily for up to 8 weeks [ 6 ].…”

“…Moreover, a 61-year-old male, diagnosed with superficial basal cell carcinoma at the Royal Brisbane Hospital (Australia), was reported to have vitiligo-like depigmentation over the treated area after using imiquimod 5% for five nights per week for almost 13 weeks [ 13 ]. Finally, a 25-year-old Caucasian female with no personal or family history of vitiligo was followed up at Ospedale Maggiore Policlinico di Milano Hospital (Italy) with multiple genital warts involving the vulvar area; she developed genital depigmentation following the use of imiquimod 5% cream three times weekly for 18 months [ 5 ].…”

Rare Cutaneous Side Effects of Imiquimod: A Review on Its Mechanisms, Diagnosis, and Management

“…Similarly, Alatabani et al [ 31 ] reported a case of a patient who experienced depigmentation at both the treated and nontreated sites after topical treatment of genital warts with imiquimod 5% cream. Serra et al [ 36 ] reported an interesting case in which, in addition to hypopigmentation at the sites of application, the patient developed halos of hypomelanosis around multiple preexisting melanocytic nevi of the trunk following topical administration of imiquimod for vulvar condylomata. In these reports, patients denied using any topical treatment other than imiquimod.…”