Cutaneous Diseases of the External Genitalia. The patients with cutaneous diseases of the external genitalia are usually concerned about a presence of sexually transmitted diseases, but other cutaneous diseases of inflammatory or autoimmune origin also present as cutaneous diseases of the external genitalia. The commonly found cutaneous diseases of the external genitalia are inflammatory diseases, such as contact dermatitis, psoriasis, Reiter's syndrome, Lichen planus, seborrheic dermatitis, balanitis, and balanoposthitis. Also sexually transmitted diseases are mainly composed of syphilis, genital herpes, lymphogranuloma venereum, condyloma, and molluscum contagiosum. The sexual partners of these sexually transmitted diseases need treatment at the same time. Fungal diseases, such as tinea and candidiasis also occur in genital areas and need careful diagnosis. Autoimmune diseases, such as Behcet's disease, also manifest as ulcerative lesions in the genital areas.