SCROTAL SKIN DISEASES I: CHEMICAL AND INFECTIOUS
Many skin diseases of infectious, allergic, or metabolic origin can involve the scrotum. Among many yeasts, molds, and fungi, only a few are infectious and are termed dermatophytes (“skin fungi”). Skin fungi live only on the dead layer of keratin protein on the skin surface. They rarely invade deeper and cannot live on mucous membranes. Infections by the fungus tinea cruris (ring-worm) are very common in the groin and scrotum. It involves desquamation of the scrotal skin and contiguous surfaces of the inner thighs and itches (“jock itch”). Tinea begins with fused, superﬁcial, reddish-brown, well-deﬁned scaly patches, which extend and coalesce into large, symmetrical, inﬂamed areas. The margins of the lesions are characteristically distinct. The initial lesion may become macerated and infected and is painful and itches. Sweating, tight clothing or obesity favor development and recurrence of this fungal infection, derived mainly from the genera Trichophyton and Microsporum. These same organisms cause tinea pedis or “athlete’s foot.”
Contact dermatitis (dermatitis venenata) is a localized rash or irritation of the skin caused by contact with a foreign substance. Only the superﬁcial regions of the skin are affected, including the epidermis and the outer dermis. Unlike contact urticaria, in which a rash appears within minutes of exposure and fades away within minutes to hours, contact dermatitis takes days to fade away. The most common causes of allergic contact dermatitis are poison ivy, poison oak, and poison sumac. Common causes of irritant contact dermatitis are highly alkaline soaps, detergents, and cleaning products. Contact dermatitis of the scrotum may show a variety of lesions varying from erythema, to papules, to vesicles or pustules, but is always accompanied by itching. The scrotal skin is usually swollen, occasionally edematous, painful, and red. Treatment is directed toward discovery and elimination of the speciﬁc cause. Drug eruption is a form of contact dermatitis that may occur on the scrotum and elsewhere on the body after consumption of drugs to which the patient is allergic.
Allergic eczema or atopic dermatitis often occurs together with other atopic diseases like hay fever, asthma, and conjunctivitis. It is a familial and chronic disease and can appear or disappear over time. Atopic dermatitis can often be confused with psoriasis. It usually begins with superﬁcial excoriation, localized edema, and exudation, following which the lesion progresses to dry, thickened skin with scale formation and a brownish hue. Marked pruritus or itching and pustule formation are characteristic. The underlying cause remains obscure. Herpes simplex virus type II (HSV-2, see Plate 2-21) is a form of genital herpes located on the genitals that is more commonly observed on the penis than the scrotum.
Intertrigo or thrush is an erythematous, inﬂammatory condition occurring where contiguous skin surfaces are moist and warm. It is caused by the yeast Candida albicans that is normally found on the skin. It is usually symmetrical on the scrotum and inner surfaces of the thighs, with frequent involvement of the penis and buttocks. Abrasions may lead to ﬁssures and maceration, with the skin becoming secondarily infected with bacteria. If the diagnosis is in doubt, a KOH test can be performed to detect the candida yeast. A bacterial culture can help diagnose a secondary bacterial infection. Intertrigo is treated with antifungal creams such as clotrimazole and miconazole. Equally important is to keep the skin folds as dry as possible.
Other rare skin lesions (not illustrated) with a predilection for the scrotum are prurigo, which is a general term for itchy eruptions of the scrotal skin, and lichen planus, an inﬂammatory skin rash that forms scaly rings and plaques on the genitalia that are characteristically “violaceous” or purple colored. Erythrasma of the genital region, a chronic infection by the bacteria Corynebacterium minutissimum, appears as a brown, scaly, ﬁnely demarcated eruption that produces no symptoms. Tinea versicolor, caused by the fungus Pityrosporum ovale, is relatively common in adolescent and young adult males. It appears as enlarging brown macules without inﬂammation or other symptoms and is treated with typical antifungal creams.