Diseases of the Genitals and Perineum

INTRODUCTION TO CHAPTER

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A stroll down the pharmacy aisle is proof enough that genital symptoms plague our population. The sheer number of products such as cleaning wipes, douches, anti-itch sprays, and antifungal preparations is overwhelming. Many patients will go to great lengths to solve genital symptoms on their own, whether motivated by embarrassment, lack of access to medical care, or uncertainty as to which medical professional is best suited to treat the problem. Indeed, many clinicians also share this uncertainty. On the other hand, patients can be too certain of a diagnosis, for example ascribing any vulvar itching, burning, or discomfort to a yeast infection. Diseases are often diagnosed via telephone, and medications (especially antifungal treatments) are often prescribed without a physical examination.

ANATOMY

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Knowledge of normal genital anatomy, as well as normal variants of the male and female genitalia, must form the basis for any approach to diagnosing genital disease.

Keratinized, hair-bearing skin is present on the scrotum and penile shaft in males and on the labia majora in females.
Modified mucous membranes with a minimal keratin layer are present on the glans in males and medial labia majora and labia minora in females.
True mucous membranes with no keratin layer are present on the urethral meatus in males and the vagina and introitus beginning at Hart’s line in females.

In males, surgical removal of the prepuce (foreskin) decreases the incidence of penile cancers, genital warts, psoriasis, erosive lichen planus, lichen sclerosus, and several sexually transmitted infections including herpes simplex and human immunodeficiency virus (HIV).¹

Knowledge of anatomic boundaries, and the typical locations of certain conditions, may aid the clinician in distinguishing diseases with similar morphologic features. For example, involvement of the mucous membranes favors lichen planus over lichen sclerosus. Involvement of the intertriginous regions favors a candida infection, whereas sparing of the creases may implicate a contact dermatitis. A well-defined, scaly red plaque involving the scrotum may suggest lichen simplex chronicus, while tinea cruris, which is also red, scaly, and itchy, tends to spare the scrotum and favor the skin folds.

Normal variations of the genitalia commonly lead patients to seek medical attention, often in the setting of new-onset symptoms, or at the initiation of sexual activity. In the latter situation, these variants may be mistaken for sexually transmitted infections. This is often the case with pearly penile papules and vulvar papillae, which are present in more than one-third of uncircumcised males and premenopausal women, respectively; both are frequently misdiagnosed as genital warts.² Unlike warts, these papules are usually symmetric, exhibit domed rather than filiform tips, and have a discrete base. Prominent sebaceous glands (Fordyce spots) are also commonly mistaken for genital warts. These 1 to 2 mm yellowish papules occur on the modified mucous membranes, including the labia minora and distal shaft of the penis, and may coalesce to form thin plaques.³

APPROACH TO DIAGNOSIS

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Skin diseases of the genitals and perineum can be classified into four broad categories (see Table 39-1).

Table 39-1.Differential diagnosis for diseases of the genitals and perineum.

Disease	Notes	History	Physical Examination
Dermatitis
Irritant contact dermatitis (ICD)	Common F > M No previous sensitization needed	Irritation, pain, soreness, burning, stinging occurring weeks after exposure to weak irritants (soaps) and immediately after exposure to strong irritants (bleach)^3,4	Chronic ICD: ill-defined pink patch or thin plaque. May have slight scale Acute ICD: red edematous plaques, may be vesicular
Allergic contact dermatitis	Common F > M Delayed-type hypersensitivity reaction; requires prior sensitization	Pruritic. Often history of exposure to prescription or over-the-counter medications (eg, benzocaine, topical antibiotics, and spermicides)^3,5	Red, edematous plaques, may be vesicular, on labia majora in females and penis and scrotum in males, perianal involvement in both sexes
Lichen simplex chronicus	Common F > M Often prior history of atopy	Severe, paroxysmal pruritus, worse at bedtime³	Pink, poorly marginated papules and plaques with epidermal thickening, hypo- or hyperpigmentation, prominent skin markings, scale on labia majora in females (Figure 39-1), scrotum in males
Papulosquamous
Lichen planus	Uncommon F > M Onset between ages 50 and 60. Most common noninfectious erosive condition of vulva. Almost nonexistent in circumcised men Rare association with hepatitis C	May be pruritic, burning, or painful. Possible dyspareunia or dysuria if vagina involved. Elicits rubbing, not scratching	White, lacy patches, flat-topped papules forming plaques, or glossy red vulvar erosions.³ May have loss of architecture with scarring. Annular lesions on penile shaft. May involve nongenital skin, vaginal, or oral mucosa
Lichen sclerosus	Common F > M Prevalence between 1/300 and 1/1000.⁴ Bimodal peaks: childhood and later life (postmenopausal)	Pruritic. Painful if secondary ulceration/erosions present	White papules/plaques. Shiny, wrinkled cigarette-paper appearance.³ Ecchymoses and purpura are pathognomonic (Figure 39-2). Scarring or loss of architecture (Figure 39-3). Spares vagina (unlike lichen planus). Perianal involvement in females only. Phimosis in young boys
Fungal
Candidiasis	Common F > M. Obesity, incontinence, diabetes, immunosuppression, corticosteroid therapy, pregnancy, infected sexual partner, and antibiotics use predispose	Irritation, pruritus, and burning	Red plaques with scale and satellite pustules (Figure 39-4)³ Women may have vaginal discharge. In uncircumcised men, penis is often involved
Tinea cruris	Common M > F	Pruritic or asymptomatic	Well-defined pink plaques with peripheral scale in inguinal folds and upper medial thighs, scrotum is spared (Figure 39-5)
Viral
Herpes simplex (HSV)	Common. Most common cause of genital ulcers. 80% of genital HSV caused by HSV-2.¹¹ 90% of HSV-2 carriers unaware of infection. 70% of HSV-2 infections transmitted during asymptomatic shedding^3,6	Prodrome: tingling, burning Acute onset of painful ulcers. Primary episode occurs 2-7 days after exposure	Small 1-3 mm vesicles on erythematous base (Figure 39-6). May rupture, forming shallow erosions. Most common on the genitals, perianal area, or buttocks
Genital warts Human papillomavirus (HPV)	Common. Risk proportional to number of lifetime sexual partners, increased in immunosuppressed individuals.⁷ Peak age: mid teens to early 30s	Onset after sexual activity. Often asymptomatic. May cause pruritus, pain, bleeding, and burning	Pink, brown, red, black, or skin-colored papules and plaques (Figure 39-7A and B). Women may have cervical warts; men may have perianal warts⁷
Molluscum	Common. Bimodal distribution: children <15 years, young adults 15-29 years (as STI).⁸ Immunosuppression and atopic dermatitis predispose	Incubation period weeks to months. Lesions often asymptomatic. Secondary eczematization may cause itch and pain	Firm, smooth, umbilicated papules. May exhibit Koebner phenomenon
Bacterial
Erythrasma	Uncommon M > F More common in humid climates	Usually asymptomatic	Well-defined plaques in inguinal folds and upper medial thigh. Coral red color with Wood’s light (Figure 39-8A and B)
Hidradenitis suppurativa	Uncommon F > M. Prevalence is 1%. Obesity is risk factor. Onset after puberty	Chronic painful and tender lesions which only partially respond to antibiotics⁹	Red cysts and nodules in inguinal, perianal, and genital areas. Axilla and inframammary areas may also be involved (Figures 15-11 and 15-12)
Perianal streptococcal disease	Uncommon Children > adults. Incidence unknown	Persistent perianal itch or pain. May have pain with defecation. Satellite pustules may indicate staphylococcal infection	Sharply demarcated perianal erythema (Figure 39-9), may have fissures, characteristic foul odor.¹⁰ May involve vulva, scrotum, and penis
Syphilis	Uncommon M > F Incidence in the United States increasing. Most new cases in men who have sex with men, ages 15-40 years¹¹	Primary ulcer: 3 weeks after exposure Secondary: 2-10 weeks after primary ulcer Tertiary: 3-10 years after primary Primary and secondary lesions resolve without treatment	Primary: painless ulcer (chancre) appears within 3 weeks of transmission, usually single, often glans penis in males, vulva (Figure 39-10) or cervix in females Secondary: condylomata lata (soft pink papules and nodules in perineum)
Precancerous tumors and cancer
HPV-related squamous cell carcinoma in situ	Uncommon F > M Younger patients with history of genital warts	Indolent asymptomatic course. Less likely to be invasive	Multifocal red, brown, or skin-colored papules or plaques on penis or perianal area in males and females and in vestibule, labia majora, and perivulvar area in females⁷
Non-HPV related squamous cell carcinoma in situ	Uncommon F > M Older patients. May have history of lichen sclerosis/planus	May be pruritic	Unifocal red, white, or skin-colored papules typically on penis, and perianal area in males and vestibule and labia minora in females (Figure 39-11A and B)
Invasive squamous cell carcinoma	Uncommon F > M Peak age of onset is 60-70 years. May have history of genital warts or lichen sclerosus/planus^3,12	May be tender or pruritic	May present as an ulcer, plaque or exophytic nodule (Figure 39-12) typically on the labia minora or majora or clitoris in females¹³ and on the penis in males
Melanoma	Uncommon M > F Rare <1% of all melanomas. May be amelanotic¹⁴	Usually asymptomatic	Tan to black papule or plaque with asymmetry, irregular color, and indistinct borders. May be ulcerated
Extramammary Paget’s disease	Uncommon F > M Onset after 50 years of age. 15-30% are associated with malignancy¹⁵	Asymptomatic, indolent	Well-demarcated pink scaly plaque with white epithelium on vulva or perineum (Figure 39-13)