A 24-year-old female presented with erythematous papules without itch and pain around the vulva. The lesions first appeared 3 weeks prior to consultation (PTC) as one erythematous papule on the vulva, then spread to the pubic area. She admitted having promiscuity, and mostly her partners did not use condoms. Physical examination on the pubic and vulva showed erythematous papules with umbilication at the central part (). Venereal disease research laboratory (VDRL), Treponema pallidum hemagglutination (TPHA), and human immunodeficiency virus (HIV) tests were nonreactive. The patient was treated with 20% KOH solution applied by the patient once daily before bedtime for 25 days. The patient felt a stinging sensation a short time after the first 5 minutes of the application. The MC lesions gradually subsided from day 17 after treatment, disappeared on day 25, and became post-inflammatory hyperpigmentation on day 51 of observation.
A 26-year-old male presented with multiple skin-colored umbilicated papules on the penis, without itch and pain (). The lesions first appeared as one skin-colored papule on the penis shaft for the past 1 month PTC. Over time, 3 weeks after, the skin lesions were spread over the base of the penis and increase in number. There was a history of promiscuity with several female prostitutes. Physical examination on the shaft and the base of the penis revealed several papules with central umbilication. VDRL, TPHA, and HIV tests were nonreactive. The patient was treated with 20% KOH solution applied by the patient twice daily for the lesions. All of the MC lesions disappeared on day 20 of observation. The patient felt a stinging sensation after 3–5 minutes application of the 20% KOH solution. Furthermore, it also caused other side effects such as erosions and post-inflammatory hypopigmentation.