Genitals

OVERVIEW

A large number of conditions involve the skin and mucous membranes of the pubic and genital regions: sexually transmitted diseases such as syphilis, venereal warts, herpes virus infections, molluscum contagiosum, scabies, and pediculosis pubis (“crabs”). A vast number of cutaneous disorders that are found elsewhere on the body, such as psoriasis, atopic dermatitis, seborrheic dermatitis, and lichen planus, are also found in the genital area.

SCROTUM/VULVA

Lichen Simplex Chronicus/Atopic Dermatitis

Lichen simplex chronicus (LSC) is a localized form of eczema, characterized by severe, persistent itching and scratching. Scrotal and vulvar eczema is a common cause of chronic genital itching. Many patients who have LSC also have atopic dermatitis elsewhere on their body or have other atopic symptoms.

LSC refers to a localized area of lichenification, which is the hallmark lesion of chronic eczematous dermatitis (thickened epidermis and an exaggeration of normal skin markings) that is induced and exacerbated by scratching and rubbing.

In addition to the scrotum and vulva, LSC is also seen on the nape of the neck, scalp, wrists, extensor forearms, ankles, pretibial areas, and inner thighs. It is more likely to occur in adults than in children (see also Arms and Legs).

Figure 16-1 Lichen simplex chronicus.

An intensely pruritic, erythematous plaque with evolving lichenification located on the scrotum and the proximal shaft of the penis.

Distinguishing Features

Chronic or paroxysmal pruritus is the primary symptom
Thick, leathery skin due to constant scratching and rubbing results in thickening of the skin and exaggerated skin markings (lichenification), with little or no scale (Fig. 16-1)
In men, LSC occurs particularly in the posterior portion of the scrotum and the crural creases (Fig. 16-2); the penis is generally spared
In women, the labia majora is most often affected (Fig. 16-3)
Perianal skin is often involved in both sexes

Diagnosis

The diagnosis is readily apparent and is made on clinical grounds

Figure 16-2 Lichen simplex chronicus.

Later stage showing pronounced lichenification and postinflammatory hyperpigmentation.

Figure 16-3 Lichen simplex chronicus.

Intensely pruritic, erythema involving the labia majora, perianal area, and surrounding inguinal creases with early lichenification in this 55-year-old woman.
Atopic history is sometimes obtained
The exclusion of candidiasis and tinea cruris
The diagnosis is confirmed by the rapid response to topical anti-inflammatory therapy with topical steroids

Helpful Hints

A chronic itchy scrotal or vulvar rash is rarely the result of a fungal infection, since tinea infections tend to involve the inguinal areas and spare the scrotum and labia
Allergic or irritant contact dermatitis from overwashing, feminine hygiene products, spermicides, and various topical medications, condoms and diaphragms, should also be considered as possible causes (Fig. 16-4)

Management

Avoid scratching and rubbing (this can be very difficult if the condition is chronic)
Eliminate harsh soaps, scrubbing, irritants, and overwashing
Unfortunately, many patients scratch themselves in their sleep; consequently, a soporific antihistamine such as doxepin (10 to 20 mg at bedtime) can help reduce nocturnal pruritus
The application of a potent class II such as fluocinonide or a superpotent class 1 topical steroid such as clobetasol, even for 1 week or more, if necessary, followed by a lower-potency, intermediate-strength (class 3 or 4) topical steroid, may help break the chronic itch-scratch cycle
Patients should be advised that recurrences are to be expected; therefore, the long-term use of the lowest-potency topical steroids and less frequent applications should be encouraged

Alternatively, for longer-term use:

Tacrolimus 0.1% ointment (Protopic) once or twice daily
Pimecrolimus 1% cream (Elidel) once or twice daily
Crisaborole 2% ointment (Eucrisa) twice daily

Figure 16-4 Allergic contact dermatitis.

Topical benzocaine and triple antibiotic ointment has resulted in this ill-defined erythematous eruption.

(Reprinted with permission from Edwards L. Genital Dermatology Atlas. Wolters Kluwer; 2004.)

Scrotal Cyst

Distinguishing Features

Solitary or multiple (Fig. 16-5) white cystic lesions
When incised, a cheesy-white, rancid, malodorous keratin material can be expressed
Such cysts may calcify

Angiokeratomas of Fordyce

Distinguishing Features

Asymptomatic 2 to 3 mm red-to-blue papules; solitary or multiple
They occur on the medial labia minora in women and the scrotum in men (Figs. 16-6 and 16-7)
The overlying surface may show slight scales (hyperkeratosis)

Diagnosis

Clinical
Shave biopsy only if diagnosis is in doubt

Figure 16-6 Angiokeratomas of Fordyce, vulva.

These are small dark purple papules most often appear on the labia majora.

Figure 16-7 Angiokeratomas of Fordyce, scrotum.

These red-purple papules are most often found on the scrotum; they are usually first noticed during young adulthood.

MALE AND FEMALE EXTERNAL GENITALIA

Molluscum Contagiosum

Distinguishing Features

Dome-shaped waxy or pearly papules with a central white core (umbilication)
Lesions generally 1 to 3 mm in diameter, but may coalesce into double or triple lesions and become “giant” mollusca
Generally asymptomatic; may itch and become inflamed (Fig. 16-8)

Diagnosis

Clinical
A handheld magnifier or dermatoscope often reveals the central core
A short application of cryotherapy with liquid nitrogen accentuates the central core (see Fig. 3-2, A and B)
Shave or curettage biopsy if diagnosis is in doubt will show molluscum bodies

Figure 16-8 Molluscum contagiosum.

Numerous inflamed lesions in a man who shaved the suprapubic area.

Pubic Lice (Pediculosis Pubis, “Crabs”)

Pubic Lice (pediculosis pubis, “crabs”) are insects that infest the pubic hair and survive by feeding on human blood. They are most often spread by sexual contact. The pubic louse gets the nickname of “crab” from its large front claws. The claws enable the lice to grasp the coarser pubic hairs in the groin, perianal, and axillary areas. Heavy infestation with pediculus pubis may also involve the eyelashes, eyebrows, and facial hair. The lice cannot survive off of the human host for more than 1 day.

Distinguishing Features

The primary symptom of infestation is pubic itching
Often, a sexual partner has “crabs”

Diagnosis

Pubic lice are diagnosed easily because they are visible to the naked eye at the base of hairs (Fig. 16-9). They are pinhead size, oval in shape, and grayish, but they appear reddish-brown when full of blood from their host
Nits (ova), the tiny white eggs, also are visible and usually are observed clinging to the base of pubic hairs
Blue macules (maculae caeruleae) may occur on nearby skin

Management

Lotions and shampoos that will kill pubic lice are available both over the counter and by prescription
Permethrin agents are usually the first line of treatment, although resistance to permethrin has become an increasingly important problem
Permethrin 1% is available OTC as Nix and Rid
A 5% permethrin (Elimite) is available only by prescription
- Topical spinosad (Natroba and generic) and topical ivermectin (Sklice) work by interfering with the lice’s nervous system and are both approved for head lice but may be tried for pubic lice
Malathion (Ovide), FDA approved only for use against head lice, may be effective against pediculosis pubis
Mercuric oxide ointment and petrolatum (twice daily for 7 to 10 days) is often used, with good results, for eyelash infestation
Treatment should include contacts of infested patients, especially sexual partners
Shaving of pubic or body hair is not necessary to treat lice

Helpful Hint

In recalcitrant cases, particularly after repeated treatment failures, “delusions of parasitosis” should be considered in the differential diagnosis in adult patients

Figure 16-9 Pubic lice (pediculosis pubis, “crabs”).

A small brown crab louse is seen at the base of hairs (arrow).

Scabies

Figure 16-10 Scabies.

Characteristic distribution of a scabies infestation in the finger webs and scrotum.

Figure 16-11 Scabies.

These are extremely pruritic papules on the shaft, mons pubis, and glans penis.

(Image courtesy of Robert I. Rudolph, MD.)

Lichen Sclerosis

Lichen sclerosis (LS), formerly referred to as lichen sclerosis et atrophicus, is a chronic inflammatory condition of unknown etiology. The peak incidence is in perimenopausal and postmenopausal women with a second peak in girls 8 to 13 years of age. Genital skin and mucosa are affected most frequently, but extragenital lesions of LS also occur. Kraurosis vulvae is an older term that was used to describe LS that was limited to the vulvar area. LS that involves the glans penis is known as balanitis xerotica obliterans. It is seen almost exclusively in uncircumcised men.

Distinguishing Features

Females