Esomeprazole-induced DRESS syndrome. Studies of cross-reactivity among proton-pump inhibitor drugs. Allergy 2007; 62: 1342-1343. 2 Ogawa K, Morito H, Hasegawa A et al. Elevated serum thymus and activation-regulated chemokine (TARC/CCL17) relates to reactivation of human herpesvirus 6 in drug reaction with eosinophilia and systemic symptoms (DRESS)/drug-induced hypersensitivity syndrome (DIHS). Br J Dermatol 2014; 171: 425-427. 3 Ogawa K, Morito H, Hasegawa A et al. Identification of thymus and activation-regulated chemokine (TARC/CCL17) as a potential marker for early indication of disease and prediction of disease activity in drug-induced hypersensitivity syndrome (DIHS)/drug rash with eosinophilia and systemic symptoms (DRESS). J Dermatol Sci 2013; 69: 38-43. 4 Almudimeegh A, Rioux C, Ferrand H, Crickx B, Yazdanpanah Y, Descamps V. Drug reaction with eosinophilia and systemic symptoms, or virus reactivation with eosinophilia and systemic symptoms as a manifestation of immune reconstitution inflammatory syndrome in a patient with HIV? Br J Dermatol 2014; 171: 895-898.Spontaneous regression of genital warts at untreated sites following electrocoagulation treatment for lesions at the other sitesDear Editor, Although warts often persist for years, it is well known that spontaneous regression can be sometimes observed. For the mechanism of the regression, it is currently accepted that cellular immune response plays a crucial role. 1 However, it is still a major question how the immunological reactions can be spontaneously generated in a subset of patients. 2 A 40-year-old otherwise healthy Japanese man suffered from human papillomavirus (HPV)-6-induced genital warts (condyloma acuminate) around the anus for 6 months. Before he visited our hospital, he had been treated with topical imiquimod cream for 3 months and then with liquid nitrogen cryotherapy for the following 2 months at a local dermatology clinic. However, clinical signs of regression were not apparent at his initial attendance (Fig. 1a). He did not have any sexual partners. The patient showed no clinical or laboratory signs of immunodeficiency. Histological examination (Fig. 1b) showed acanthosis, papillomatosis, hyperkeratosis and dilatation of the small vessels with infiltrations of marked mononuclear cells and a few macrophages in the dermis. Intraepithelial mononuclear cell infiltration was also observed. Koilocytosis was not observed. 3 Although HPV antigen was not detected immunohistochemically, polymerase chain reaction analysis demonstrated the presence of HPV-6 DNA. Figure 1. (a) Pretreatment clinical feature of perianal genital warts. (b) Histopathological examination revealed hyperkeratosis, acanthosis, dilated blood vessels and mononuclear cell infiltration in the upper dermis (hematoxylin-eosin, original magnification 940). (c) Clinical features after scissor excision followed by electrocoagulation of selected lesions. (d) Clinical features 1 month after the treatment, showing almost complete resolution of the warts left untreated.