Inguinal and genital porokeratosis are rare but seem to be more common in Asians. We report a case of a 69-year-old Japanese man with multiple lesions of porokeratosis in both inguinal regions. The lesions first appeared in the inguinal region and subsequently spread to the trunk. The patient reported that his father had had similar lesions. Dermoscopy demonstrated central brown pigmentation and blue-gray dots surrounded by a single "white track" at the periphery. The exterior border of the white track also showed light brown pigmentation. Genital or inguinal porokeratosis is uncommon and may be misdiagnosed as Bowen's disease, lichen planus or extramammary Paget's disease. However, awareness of this entity and the use of dermoscopy are helpful to establish a correct diagnosis.
Keywords: dermoscopy; genital; inguinal; porokeratosis.