Anogenital skin and mucosa are subject to unique disorders because of their special anatomy.
Dermatologic and systemic disorders occur in the anogenital region.
Primary neoplasms arise in these areas, most commonly associated with chronic human papillomavirus (HPV) infection.
Sexually transmitted as well as other infections also occur commonly in these sites.
Often normal structures, newly observed, give rise to great concerns about sexual transmitted infections such as anogenital warts and molluscum contagiosum.
Pearly Penile Papules ICD-9: 607.89 ° ICD-10: N48.89 
Normal anatomic structures. Incidence: Up to 19%.
Symptoms: Asymptomatic; may arouse some anxiety when first noted.
Clinical findings: Skin-colored 1- to 2-mm, discrete, domed papules evenly distributed circumferentially around the corona (Fig. 34-1), giving a cobblestone pattern.
Differential diagnosis: Condylomata acuminatum, molluscum contagiosum.
Histology: Angiofibromas.
Management: Reassurance: normal anatomic structures.
Synonym: Angiofibromas.
Figure 34-1. Pearly penile papules Pink (skin-colored), 1- to 2-mm papules are seen regularly spaced along the corona of the glans penis. These structures, which are part of the normal anatomy of the glans, are commonly mistaken for condylomata or molluscum contagiosum.
Sebaceous Gland Prominence ICD-9: 789,9 ° ICD-10: Q89.9
Normal sebaceous glands. Analogous to sebaceous gland on mucosa of mouth.
Locations: Penis, vulva.
Manifestation: 2-mm dermal papule; cream colored. May be arranged in rows.
Synonyms: Tyson glands, sebaceous hyperplasia, “ectopic” sebaceous glands, Fordyce condition.
Angiokeratoma (See also Section 9)
Ectatic thin-walled blood vessels in the superficial dermis with overlying epidermal hyperplasia.
Increasingly common with aging.
Multiple purple, smooth, 2- to 5-mm papules. Bleed with trauma. (See Section 9, Fig. 9-25).
Location: Scrotum, glans penis, penile shaft. Labia, vulva.
Differentiate from angiokeratomas of Fabry disease (usually pinhead size, found on bathing trunk area and upper thighs), Kaposi sarcoma.
Management: Reassurance, electrosurgery.
Synonym: Angiokeratomas of Fordyce.
Sclerosing Lymphangitis of Penis ICD-9: 607.2 ° ICD-10: N48.29 
Etiology Trauma associated with vigorous sexual activity.
Pathogenesis: Lymphatic stasis may result in thrombosed lymphatic vessels. Subsequent recanalization and fibrosis of walls of lymphatic vessels.
Clinical findings: Painless, firm, at times nodular, translucent serpiginous cord appears suddenly,
usually parallel to corona; not attached to overlying epidermis (Fig. 34-2).
Course: Resolves spontaneously in weeks to months.
Synonyms: Nonvenereal sclerosing lymphangitis, penile venereal edema, Mondor phlebitis.
Figure 34-2. Sclerosing lymphangitis: penis A dermal cord on the distal shaft parallel to the corona.
Lymphedema of the Genitalia ICD-9: 457.1 ° ICD-10: 189.0 
Acute idiopathic scrotal edema. Occurs in young boys. Resolves spontaneously in 1-4 days. Differentiate from acute scrotum. Also reported in adults with dengue hemorrhagic fever, Henoch-Schönlein purpura.
Lymphogranuloma venereum (see Section 30). Occurs in chronic undiagnosed infection. Both sexes. Referred to as esthiomene: elephantiasis due to lymphatic obstruction. Chronic. Deformity of penis referred to as “saxophone penis.”
Chronic recurrent bacterial infection may be causative (Fig. 34-3A, B).
Kaposi sarcoma.
Filarial or lymphatic elephantiasis. Caused by parasitic worms such as Wuchereria bancroftii, Brugia malayi, B. timori. Associated with elephantiasis of legs.
Synonym: Lymphangiofibrosis thrombotica occlusiva.
Figure 34-3. (A, B) Chronic lymphedema: scrotum A 29-year-old male with history of recurrent scrotal infections that have destroyed lymphatic channels. There is scrotal noncompressible lymphedema and the penis is retracted.
Plasma Cell Balanitis and Vulvitis
Asymptomatic red glistening plaque(s) on glans penis (Fig. 34-4) or vulva.
Differentiate from squamous cell carcinoma in situ.
Management: Circumcision is curative in uncircumcised males. Otherwise, topical corticosteroids, calcineurin inhibitors, and imiquimod can be used. Electrosurgery and laser destruction have also been reported.
Synonym: Zoon balanitis.
Figure 34-4. Plasma cell balanitis Solitary red glistening plaque for 10 years in an uncircumcised male.
Phimosis, Paraphimosis, Balanitis Xerotica Obliterans ICD-9: 607.81 ° ICD-10: N48.0 
Phimosis: nonretractable foreskin. Etiology: Lichen sclerosus, nonspecific balanoposthitis (posthitis is inflammation of foreskin or prepuce), lichen planus, cicatricial pemphigoid, chronic lymphedema, Kaposi sarcoma. Precludes examination of glans for precancerous changes (Fig. 34-5).
Balanitis xerotica obliterans (BXO): End stage of chronic phimosis. Foreskin fibrotic, contracted, fixed over glans and cannot be retracted over glans. Most often end-stage lichen sclerosus, which is commonly referred to as BXO (see Section 14, lichen sclorosus).
Paraphimosis: Foreskin fixed in retraction. Etiology: vigorous sexual activity, acute contact urticaria, acute allergic contact dermatitis, lichen sclerosus (Fig. 34-6).
Figure 34-5. Phimosis The prepuce or foreskin has been chronically inflamed with scarring and is no longer retractable over the glans penis.
Figure 34-6. Paraphimosis The prepuce or foreskin has been retracted proximally over the glans and cannot be replaced to the normal position covering the glans. The shaft is edematous.
Mucocutaneous Disorders
Genital (Penile/Vulvar/Anal) Lentiginoses ICD-9: 709.8 ° ICD-10: L98.8
Onset: Adulthood.
Clinical findings: Tan, brown, intense blue-black; usually variegated, 5- to 15-mm macules.
Sites: In clusters on vulva (labia minora, Fig. 34-7), penis (glans, shaft) (Fig. 34-8), and perianal areas.
Course: Persist for years without change in size.
Histology: No significant melanocytic hyperplasia; nevus cells are not present; pigmentation due to increased melanin in basal cell layer.
Differential diagnosis: Melanoma in situ, PUVA lentigo, fixed drug reaction, blue nevus, HPV-induced intraepithelial neoplasia (IN).
Diagnosis: Dermoscopy rules out in situ melanoma; histology confirms diagnosis.
Extensive lesions that cannot be easily removed should be followed photographically; areas that show significant change should be biopsied.
Synonyms: Penile lentigo, vulvar melanosis.
Figure 34-7. Genital lentiginoses: vulva Multiple, variegated dark brown macules, bilaterally on the labia minora. Acrolentiginous melanoma in situ must be ruled out.
Figure 34-8. Genital lentiginoses: penis Variegated macular pigmentation of the glans and foreskin for over 20 years. Biopsy ruled out melanoma and HVP-infection (SCCIS).
Vitiligo and Leukoderma (See also Section 13) 
Etiology: Loss of melanocytes results in depigmentation.
Isomorphic or Koebner phenomenon: Depigmentation at sites of injury: genital herpes, cryosurgery, imiquimod therapy.
Wood lamp examination: Differentiates depigmentation from hypopigmentation.
Clinical findings: Sharply demarcated, depigmented, white macules (Fig. 34-9); examine skin for other depigmented areas.
Differential diagnosis: Lichen sclerosus, site of genital herpes; iatrogenic after cryo-, electro-, or laser surgery.
Figure 34-9. Vitiligo: penis Multiple depigmented macules have become confluent.
Psoriasis Vulgaris (See also Section 3)
Incidence: Most common noninfectious dermatosis occurring on the glans penis and vulva.
Onset: May be initial presentation of psoriasis.
Clinical findings: (1) Erythematous scaling plaques on nonoccluded skin (Fig. 34-10); (2) intertriginous psoriasis, well-demarcated erythematous plaques without scale in naturally occluded skin (Fig. 34-11).
Distribution [intertriginous (inverse) psoriasis]: Penis, vulva, intergluteal cleft, inguinal folds.
Differential diagnosis: Lichen planus (LP), fixed drug eruption, condyloma acuminata, HPV-induced IN, squamous cell carcinoma (SCC) in situ, invasive SCC, extramammary Paget disease, migratory necrolytic erythema.
Figure 34-10. Psoriasis vulgaris: shaft of penis Well-demarcated scaling plaques on the penile shaft of a 25-year-old male. “Pinking” of the intergluteal cleft and nail findings of psoriasis were also present. The patient presented to a clinic for sexually transmitted disease.
Figure 34-11. Psoriasis vulgaris: intertriginous An erythematous plaque, present for decades and unresponsive to topical antifungal agents, is seen in the right inguinal area. Biopsy excluded extramammary Paget disease.
Lichen Planus (See also Section 14)
Commonly associated with LP at other sites: however, may occur as initial or sole manifestation.
Symptoms: Not pruritic; pain in eroded lesions, anxiety about sexually transmitted disease.
Clinical findings: Violaceous flat-topped papules, discrete or confluent. Lacy white surface pattern most commonly on glans. Older lesions may have grayish hue with melanin incontinence. Annular lesions occur on glans and shaft (Fig. 34-12). Bullous and/or erosive LP (Fig. 34-13) on glans, vulva.
Distribution: Glans, penile shaft (Fig. 34-12), vulva. Course: Spontaneous remission; erosive LP may persist for decades; SCC complicates rarely.
Figure 34-12. Lichen planus, annular: penis Violaceous annular plaques (arrow) on the distal shaft and glans of a 26-year-old patient, present for >1 year. White lacelike plaques were also present on the buccal mucosa.
Figure 34-13. Lichen planus, erosive: penis A 36-year-old male with painful erythematous erosions on the glans penis and foreskin for 6 months. Lesions resolved with intralesional triamcinolone injections.
Lichen Nitidus ICD-9: 697.0 ° ICD-10: L44.1
Probably micropapular variant of lichen planus.
1- to 2-mm papules on shaft of penis (Fig. 34-14).
Figure 34-14. Lichen nitidus: penis Flat-topped papules on the shaft of the penis.
Lichen Sclerosus (See also Section 14)
Symptoms: Pruritus, burning; pain with ulceration. Clinical findings: Early: erythema ± hypopigmentation. Later: typical ivory- or porcelain-white macules and plaques; white due to loss of dermal vasculature (Fig. 34-15). Ecchymosis (Figs. 34-15 to 34-17), bullae, and/or erosions may occur in involved sites. May obstruct urethral orifice.
Demography: Ten times move common in female. Causes phimosis (Fig. 34-15) in boys.
End stage: BXO. Effacement of normal architectural features: labia minora and clitoral hood may be reabsorbed (Fig. 34-16).
Course: Invasive SCC can arise in this site of chronic inflammation.
Management: Clobetasol ointment; monitor for steroid-induced atrophy, pimecrolimus, tacrolimus.
Synonym: Lichen sclerosus et atrophicus.
Figure 34-15. Lichen sclerosus: penis A 17-year-old male with phimosis (inability to retract foreskin) for 6 months and white plaques on the periurethral glans and on the reflection of the foreskin.
Figure 34-16. Lichen sclerosus: vulva and perineum A large white sclerotic plaque extensively involving the anogenital region. The clitoral and labia minora region is completely atrophic (agglutination). Ecchymoses are noted in association with atrophy. Ulcerations can occur and are painful.
Figure 34-17. Lichen sclerosus: penis (A) Whitish plaques on glans with typical ecchymoses; the urethral orifice was constricted. (B) Five years later, the penis had become atrophic and submerged within the pubic fat, making urination difficult. A white sclerotic plaque with ecchymoses is seen on the stretched skin of the ventral penile shaft.
Migratory Necrolytic Erythema (See also Section 19) 
Manifestation of glucagonoma syndrome.
Painful erythematous plaques, glistening surface, serpiginous border surrounded by scaling. (See Fig. 19-10).
Genital Aphthous Ulcerations (See also Sections 14, 27, and 33)
Idiopathic ulcers on scrotum or vulva. May be associated with oral aphthous ulcerations. May occur as a manifestation of primary HIV/AIDS.
Occur as part of the syndrome complex of Behçet disease. (See also Figs. 14-24 to 14-27).
ECZEMATOUS DERMATITIS
Allergic Contact Dermatitis (See also Section 2)
On genitalia is often more florid and symptomatic than at other sites.
Allergens: Topically applied agents (medications, lubricants); haptens blotted onto genitals by hands (e.g., poison ivy sap).
Symptoms: Intense pruritus, burning sensation; edema.
Clinical findings: Erythema, microvesicles; edema; exudation of genitals (Fig. 34-18). With phytodermatitis (e.g., poison ivy or oak), lesions are usually present at other sites.
Differential diagnosis: Genital herpes, atopic dermatitis, irritant dermatitis
Figure 34-18. Allergic contact dermatitis: penis Striking edema of the distal penile shaft associated with severe pruritus in a 21-year-old patient. He had touched poison ivy with his hands, transferring the resin to his penis while urinating. The magenta colored pigment is Castellani paint.
Atopic Dermatitis, Lichen Simplex Chronicus, Pruritus Ani ICD-9: 698.0 ° ICD-10: L29.0
Atopic dermatitis: Usually associated with more widespread involvement but can be isolated to genitalia.
Lichen simplex chronicus: Chronic rubbing/scratching results in a single plaque on scrotum (Fig. 34-19), vulva, or anus (Fig. 34-20), persisting for years or decades. In dark skin, hypo- and hyperpigmentation occurs (see Section 2).
Pruritus ani: Can occur in the absence of any identifiable dermatologic disorder. Chronic pruritus and rubbing often produce some lichenification (Fig. 34-20). Risk factors: Atopic diathesis; multifactorial. Secondary infection: Staphylococcus aureus, group A and B streptococci, Candida albicans, and herpes simplex virus. Management: Discontinue compulsive rubbing/scratching; maintenance of perianal hygiene.
Figure 34-19. Lichen simplex chronicus: scrotum Pruritic bilateral erythematous hyperpigmented plaques present for >20 years.
Figure 34-20. Lichen simplex chronicus: pruritus ani The patient had experienced intense anal pruritus for many years. Perianal erythema with mild lichen simplex chronicus and fissure is associated with chronic rubbing of the skin.
Fixed Drug Eruption (See also Section 23)
Large blisters occur on the male genitalia commonly; evolve to painful erosion (Fig. 34-21).
With repeated drug exposure, blisters/erosions recur at the same site.
Figure 34-21. Fixed drug eruption: trimethoprim-sulfamethoxazole Violaceous bullae that had ruptured, occurring on the dorsum of the penis (glans and shaft), recurring after treatment with trimethoprim-sulfamethoxazole.
Premalignant and Malignant Lesions
Squamous Cell Carcinoma in Situ (See also Section 30)
Terminology: Squamous cell carcinoma in situ (SCCIS) is generic; intraepithelial neoplasia (IN) is HPV-induced SCCIS
Etiology: HPV infection, chronic low-grade balanoposthitis (poor hygiene, LS) in older individuals; chronic dermatoses (ulcerative lichen planus, lichen sclerosus).
Clinical findings: Solitary, well-defined, irregularly bordered, red patch with a glazed-to-velvety surface hyperkeratosis on the penis or vulva; associated dermatoses. HPV-associated lesions are usually multifocal, occurring at any sites of the anogenital region (Fig. 34-22).
Diagnosis: Lesional biopsy.
Course: Appearance of a nodule or ulcer suggests progression to invasive SCC (Fig. 34-23). In HPV-associated SCCIS, rate of transformation to invasive SCC is relatively low; rate is higher for vulvar SCCIS: Rate of invasiveness and metastasis higher when associated with poor hygiene/chronic balanoposthitis. (See also Sections 11 and 30.)
Synonyms: Erythroplasia of Queyrat; Bowen disease, bowenoid papulosis.
Figure 34-22. HPV-induced squamous cell carcinoma in situ: perianal A well-demarcated pink perianal asymptomatic plaque. Anal Pap test showed low-grade squamous intraepithelial lesion (LSIL).
Figure 34-23. Squamous cell carcinoma in situ arising in lichen sclerosus: vulva Erythema and erosions with marked atrophy of the labia minora and clitoris in a patient with longstanding genital lichen sclerosus. Lesional biopsy shows associated SCC in situ arising in lichen sclerosus.
HPV-Induced Intraepithelial Neoplasia (IN) and
Squamous Cell Carcinoma In Situ (See also Section 30)
Etiology: HPV types 16, 18, 31, 33.
Risk factors: Immunosuppression, occurring in HIV/AIDS disease, iatrogenically induced immunosuppression in solid organ transplantation.
Clinical findings: Erythematous patches and papules (flat-topped) (Figs. 34-22 and 34-24); pigmented papules. Arrangement: Solitary, clustering, confluence, plaque(s) formation. Distribution: Mucosa and anogenital and inguinocrural skin.
Course: Spontaneous resolution; persist for years; multiple new lesions appear; progress to invasive SCC. Progression to invasive SCC highest in cervix, anus. Monitor cervix/anus by periodic Pap testing (cytology) to detect dysplastic changes.
IN I: mild dysplasia.
IN II: moderate dysplasia.
IN III: neoplastic cells penetrate into upper third of epithelial layers; SCCIS.
Invasive SCC: neoplastic cells penetrate stromal layer of epithelium.
Figure 34-24. HPV-induced invasive squamous cell carcinoma: perineum A 34-year-old HIV/AIDS-infected male presented with a perineal tumor (arrow) of several months duration.
Invasive Anogenital Squamous Cell Carcinoma
Invasive SCC of Penis (See also Section 11) 
Risk factors: Lack of circumcision, poor penile hygiene, phimosis (25-75%), low socioeconomic status, HPV infection (15-80%), UV-radiation exposure, tobacco use.
Demography: More common in developing nations (up to 10% of cancers in men; rare in industrialized nations).
Precancerous lesion/disorders: Phimosis, chronic balanoposthitis, pseudoepitheliomatous keratotic and micaceous balanitis, lichen planus, lichen sclerosus, giant condyloma, HPV-induced IN.
Symptoms: Precursor lesion, itching/burning under foreskin, ulceration of glans or prepuce.
Clinical findings: Subtle induration; small excrescence; small papule; warty growth to an obvious extensive carcinoma with sloughing. Necrosis and/or secondary infection in phimotic foreskin. Extends along the penile shaft and involves corpora cavernosa. Rarely, bleeding, urinary fistula, and urinary retention occur.
Distribution: Glans (48%), prepuce (21%), glans and prepuce (9%), prepuce glans and shaft (14%), coronal sulcus (6%), shaft (<2%).
Metastasis: Inguinal lymph node metastases; distant sites rare.
Invasive SCC of Vulva (See also Section 11)
Risk factors: HPV infection, abnormal cervical Pap test, immunosuppression, HIV/AIDS disease, advanced age, increased number of sexual partners, younger age at first episode of intercourse, tobacco use, lichen planus, lichen sclerosus (Fig. 34-23).
Symptoms: Vulvar pruritus, localized pain, discharge, dysuria, bleeding, ulceration.
Clinical findings: IN, bulky whitish or pigmented lesion of thickened or hard skin; verrucoid, polypoid, papular. Location: 65% arise on labia majora.
Invasive SCC of Cutaneous Anus (See also Section 11)
Etiology: Oncogenic HPV infection. Risk factors: Chronic immunosuppression, HIV/AIDS disease. Location: (1) Cutaneous, (2) junction of columnar and squamous epithelium.
Precursor lesion: Anal IN. Clinical findings: Papule, nodule, ulcerated nodule (Fig. 34-24).
Genital Verrucous Carcinoma (See also Section 30) 
Etiology HPV infection.
Clinical findings: Large, cauliflower-like, warty tumors.
Distribution: Vulva, penis, anus.
Course: Slow-growing; rarely metastasize.
Malignant Melanoma of the Anogenital Region (See also Section 12)
Incidence: Rare
Precursor lesions: Preexisting pigmented lesion or de novo from epidermal melanocytes.
Clinical findings: Macules or papules with variegation of brown-black color, irregular borders, and often with papular elevation (Fig. 34-25) or ulceration.
Distribution: Males: glans (67%), prepuce (13%), urethral meatus (10%), penile shaft (7%), and coronal sulcus (3%) (Fig. 34-25); females: labia minora, clitoris (Fig. 34-26).
Differential diagnosis: Genital lentiginosis, old fixed drug eruption, SCC, hemangioma, intraepithelial neoplasia (Bowenoid papulosis).
Histologic types: Acral lentiginous melanoma; rarely, desmoplastic melanoma.
Prognosis: Poor because of early metastases via lymphatic vessels; most patients die within 1–3 years.
Figure 34-25. Melanoma, invasive: penis A violaceous nodule (arrow) represents the vertical growth phase (VGP) arising in an area of macular variegated hyperpigmentation (arrow) which denotes radial growth phase (RGP) which had been present for 5 years and resembled genital lentiginosis. The most common histologic type of genital melanoma is acrolentiginous melanoma.
Figure 34-26. Melanoma, invasive: vulva A violaceous nodule in a black plaque is seen.
Extramammary Paget Disease (See also Section 18)
Often undiagnosed for years or decades; treated as intertrigo.
Well-demarcated plaques in genital area (Fig. 34-27).
Figure 34-27. Extramammary Paget disease (EMP): penis, scrotum, inguinal area Well-demarcated recurrent, bright red plaques for several years which had been previously excised by Mohs micrographic surgery but recurred; lesions were effectively treated with electron beam radiotherapy.
Kaposi Sarcoma (See also Section 21) 
Common in advanced untreated HIV/AIDS.
Location: Penis and scrotum.
Manifestations: Violaceous papules, nodules, plaques; become confluent. Edema of penis and scrotum (Fig. 34-28).
Figure 34-28. Kaposi sarcoma: penis Multiple nodules are seen on the glans and shaft of the penis, present for 8 months in a patient with HIV/AIDS. Massive swelling of the penis was caused by tumor infiltration and lymphatic obstruction, resulting in urinary obstruction. Similar obstruction caused edema of both legs.
Anogenital Infections (See also Sections 25, 26, and 30)
Bacterial infections, see Section 25
Mucocutaneous anogenital fungal infections, see Section 26
Dermatophytosis and tinea versicolor occur on keratinizing skin only. Rarely occur on shaft of penis.
Candidiasis is common on naturally occluded sites on the penis, vulva, vagina.
STI, see Section 30.