Histological features

The anogenital region, as with other mucocutaneous sites, is characterized by a gradual transition from skin to a mucosal surface.

Histological features

These sites most closely resemble skin from other regions of the body since the epithelium is keratinized and stratified and adnexal structures are represented. The epithelium of the labia majora normally contains occasional lymphocytes, which are found in very small numbers around the superficial dermal vasculature. In the labia majora, sebaceous glands are present in association with hair follicles and both eccrine and apocrine glands are typically present. On the medial aspect of the labia majora the hair follicles become modified and there is often no hair seen although sebaceous glands are still present (Fig. 12.2). Some may open directly onto the epithelium (Fordyce spots, see below). In the deep dermis, a layer of smooth muscle known as the tunica dartos labialis is seen. The subcutaneous tissue of the labia majora tends to be prominent in women of reproductive age but decreases in amount after the menopause. The labia majus contains a long smooth muscle called the cremaster. The skin of the perianal area shows numerous terminal hairs with sebaceous glands.

Fig. 12.2 (A, B) Normal vulva: medial aspect of labium majus. The epidermis is keratinized. The dermis is richly vascular. Hair follicles are absent.

Histological features

The labia minora represent the female equivalent of the penile corpus spongiosum. They are located lateral to the vaginal vestibule, medial to the labia majora and are covered by stratified, often pigmented, squamous epithelium. In most females, adnexal structures are absent, as is subcutaneous tissue. The stroma is richly vascular and contains abundant erectile tissue and elastic fibers.

The pilosebaceous unit is incomplete, as the sebaceous gland is not usually associated with a hair follicle and opens directly onto the surface. Sweat glands are sparse and subcutaneous fat is not seen.

Histological features

The epithelium is stratified and keratinized. No adnexal structures are present. The glans clitoris, unlike its male counterpart, does not contain a corpus spongiosum. The frenulum and the prepuce originate from the labia minora and contain abundant sebaceous and mucus-secreting glands.

Histological features

The epithelium is stratified and nonkeratinized, i.e., it is a mucosa (Fig. 12.3). Both the vagina and the urethra open into the vestibule. Bartholin’s glands are located deep to the posterior part of the labia majora. They represent the equivalent of Cowper’s glands or the bulbourethral glands in the male. The ducts of Bartholin and Skene’s glands and the minor vestibular glands open into the vestibule

Fig. 12.3 Vestibule: (A) the epithelium is nonkeratinizing and rich in glycogen. Cutaneous appendages are absent at this site; (B) the epithelium is strongly PAS positive.

Histological features

The pattern of keratinization of the epithelium varies throughout the anogenital area most markedly in the transition from true urothelium to true skin. There is controversy over the definition of ‘mucosa’ ^5,6 but there is no doubt that the penile urethra does possess a true mucosa, while the glans of the circumcised male does not; the glans and inner prepuce of the uncircumcised male probably does not display mucosa but the outer prepuce does. There are several epithelial transition zones.⁷ The proximal (pre-prostatic and prostatic) urethra is lined by transitional epithelium, the membranous spongy penile urethra by pseudostratified columnar epithelium. The distal penile urethra is lined by stratified or pseudo-stratified squamous epithelium incorporating a single layer of columnar cells at the surface and contains Littre’s glands, the distal 5–6 mm of penile urethra, which includes the navicular fossa manifests a 6–10 cell layer of nonkeratinizing squamous epithelium, contains no adnexae and is continuous with the epithelium of the uncircumcised glans (which may show some thin keratinization, although some accounts state that the glans is not keratinized in the uncircumcised) and inner preputial epithelium; the outer preputial epithelium is identical to skin.⁷ Just as there is wide variability in the size and shape of the navicular fossa, the site of the epithelial transition zones and probably the degree of keratinization of the glans and the disposition of adnexa may vary. Presumed multipotential, mucous secreting cells have been described in the perimeatal epithelium⁸ and mucinous metaplasia of glans and foreskin have also been observed.^9,10 Also, the final transition will depend on the length of the foreskin: it is our experience that male genital lichen sclerosus has a greater predilection for the male with a longer foreskin (as does penile cancer¹¹). The wide spectrum of differentiation of the male urogenital tract is accompanied by changes in the expression of epithelial cytokeratins, but this is relatively unexplored territory.¹² Normal regional histology is illustrated in Figures 12.4–12.9.

Fig. 12.4 Penis: This transverse section of the human penis shows the arrangement of the erectile tissues, which exist in the form of three columns. The two dorsal columns are called the corpora cavernosa CC and the single ventral column is the corpus spongiosum CS, through which runs the penile urethra U. At its distal end, the corpus spongiosum expands to form the glans penis. The erectile corpora are enclosed within, and separated by, a fibrocollagenous capsule F. The erectile centre of the penis is enclosed in a sheath of skin S to which it is connected by a loose subcutis containing prominent blood vessels.

Reproduced with permission from Young B. et al., Wheater’s Functional Histology, 5th edition. © Churchill Livingstone, 2006.

Fig. 12.5 Normal histology of the penis. Foreskin. Full thickness of prepuce shows all five layers: keratinized stratified squamous epithelium, dermis with sebaceous glands, dartos, submucosa and squamous mucosa. H&E.

Courtesy of and reproduced with permission from Sternberg, SS, ed. Histology for Pathologists, 2nd edition. Philadelphia: Lippincott, Williams and Wilkins, 1997.

Fig. 12.6 Normal histology of the penis, balanopreputial sulcus. Histologic components of both glans and penile body are present. This specimen from a circumcised person shows the mucosa at top, lamina propria below, then dartos, or smooth muscle layer and Buck’s fascia. H&E.

Courtesy of and reproduced with permission from Sternberg, SS, ed. Histology for Pathologists, 2nd edition. Philadelphia: Lippincott, Williams and Wilkins, 1997.

Fig. 12.7 Normal histology of the penis. Glans penis. The three layers of glans are noted: nonkeratinized stratified mucosa, lamina propria and corpus spongiosum. H&E.

Reproduced with permission from Sternberg, SS, ed. Histology for Pathologists, 2nd edition. Philadelphia: Lippincott, Williams and Wilkins, 1997.

Fig. 12.8 Anal transitional zone (ATZ). Transition from ATZ epithelium (left) to squamous zone (right). H&E.

Reproduced with permission from Sternberg, SS, ed. Histology for Pathologists, 2nd edition. Philadelphia: Lippincott, Williams and Wilkins, 1997.

Fig. 12.9 Perianal skin. Keratinized squamous epithelium and an underlying apocrine gland. H&E.

Reproduced with permission from Sternberg, SS, ed. Histology for Pathologists, 2nd edition. Philadelphia: Lippincott, Williams and Wilkins, 1997.

Clinical features

Skin tags (acrochordons) are common in the groins, especially in the obese. They may catch on clothing, bleed and get infected. Fibrosed hemorrhoids can result in perianal skin tags, but larger, fleshier, more edematous skin tags should arouse the suspicion of Crohn’s disease: they can predate gastrointestinal disease by several years.¹ These lesions are particularly relevant in young patients with diarrhea, abdominal pain and/or growth retardation.¹

Histological features

The histology of a skin tag at this site is identical to that of those occurring elsewhere. The presence of granulomata in anal skin tags is often a clue to the diagnosis of Crohn’s disease.²

Clinical features

Pearly/pink penile papules¹ may be found in 15–50% of men.^2–5 They manifest as flesh-colored, smooth, rounded papules (1–3 mm) occurring predominantly around the coronal margin of the glans, rarely on the glans. Often there are rows or rings of papules (Fig. 12.13). Ectopic lesions, for example on the penile shaft, have been reported,⁶ including in children.⁷ They are frequently mistaken for warts and Tyson’s or ectopic sebaceous glands. The lesion is analogous to other acral angiofibromas such as adenoma sebaceum, subungual and periungual fibromas, fibrous papule of the nose, acquired acral angiofibroma and oral fibroma. These lesions may regress with circumcision and old age.⁸

Fig. 12.13 Pearly penile papules. Glans penis, coronal rim.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

Histological features

The histology is that of angiofibroma.⁹ HPV DNA is absent.^10,11

Clinical features

Vestibular papillomatosis is not due to human papillomavirus infection and is a common finding of no significance.^1,2 It is asymptomatic and is the female equivalent of penile pearly papules (hirsutoid papillomas). Individual lesions are dome shaped or filiform and arise on a solitary base. They are found on the inner aspect of the labia minora and vestibule (Fig. 12.14).

Fig. 12.14 Vulval papillomatosis: numerous pale papillomata are present in the vestibule and on the labia minora. These are a normal finding and are particularly common in pregnancy.

By courtesy of the Institute of Dermatology, London, UK.

Histological features

There is a normal or thickened epidermis overlying a central fibrovascular core.

Clinical features

The sebaceous glands of the inner labia majora, the labia minora and clitoral prepuce do not usually have an associated hair follicle. The glands open directly onto the surface and may be very prominent and numerous at these sites. The yellow uniform papules (Fordyce spots) are often seen best if the skin is stretched (Fig. 12.15). Sebaceous gland hyperplasia may sometime be associated with pruritus and pain if they enlarge and the contents rupture into the dermis.

Fig. 12.15 Fordyce spots: hyperplastic sebaceous glands presenting as conspicuous yellow papules. Similar lesions may be seen on the inner lip and oral mucosa.

By courtesy of the Institute of Dermatology, London, UK.

In the male, sebaceous gland prominence, Tyson’s glands, sebaceous hyperplasia and ectopic sebaceous glands (Fordyce’s condition) are all virtually synonymous and are common, normal variants of the skin of the scrotal sac and penile shaft (very rarely the glans) but may cause concern to patients even amounting to dysmorphophobia (Fig. 12.16).^1,2

Fig. 12.16 Sebaceous hyperplasia (Fordyce’s condition). Penis, prepuce.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

Histological features

One or more enlarged sebaceous glands, each composed of numerous lobules, surround a central duct that opens directly into the epidermis (Fig. 12.17).

Fig. 12.17 Fordyce spot: this small sebaceous gland can be seen communicating directly with the epidermis.

Clinical features

These are non-specific terms.¹ Intertrigo is the name given to any dermatosis occurring in skin folds: any scale is usually rapidly removed by frictional abrasion, and a degree of epithelial loss may result in erosion that renders the site especially susceptible to secondary infection, e.g., with Candida (see below).

Balanitis denotes inflammation of the glans penis while posthitis is inflammation of the prepuce. Balanoposthitis means inflammation of the glans and prepuce and is regarded as a special form of intertrigo. By definition, therefore, balanoposthitis cannot occur in the circumcised male, but balanitis might.

Pathogenesis and histological features

Generally, dermatologists feel that balanitis, posthitis and balanoposthitis are probably more commonly due to inflammatory and precancerous dermatoses, while genitourinary physicians teach that most cases are due to infection, usually with Candida.¹ However, Candida is a ready opportunist so its presence may not always indicate primary infection as the cause of the genital inflammation. Bacteria have increasingly been implicated in the etiology of the disease, particularly Staphylococcus aureus.² In cases in which Streptococcus pyogenes is isolated it has been suggested that the disease may be sexually transmitted by penile–oral intercourse.³ Diabetes may be an important predisposing factor to Candida and other infective causes or complications of balanoposthitis.¹

The histological features are non-specific.

Clinical features

Seborrheic dermatitis is the commonest form of eczema affecting anogenital skin, followed by irritant contact eczema. Eczema, particularly seborrheic dermatitis, is more common than many other inflammatory dermatoses in uncircumcised males.¹ Allergic contact eczema is rare at genital sites and occurs more typically in a perianal distribution. Involvement of genital skin with atopic eczema is very uncommon.

In infants, eczematous reactions are often seen in the napkin area. Most of these represent a primary irritant dermatitis. Seborrheic dermatitis and a psoriasiform napkin rash can also occur. Some but not all of the patients with the latter condition develop psoriasis later in life.²

Histological features

The histological features are identical to those seen in eczema affecting other areas of the skin. Psoriasiform napkin rash shows histological features that overlap with psoriasis.

Clinical features

Infantile gluteal granuloma (papuloerosive dermatitis of Jacquet and Sevestre) is a rare condition that has been described mainly in the newborn and infants in the napkin area. It frequently develops in a background of an irritant napkin rash.^1–4 A similar condition has been described in incontinent elderly women with lesions developing on the labia majora (Fig. 12.18).^5–7 Oval or round papulonodular lesions present on the convex areas of the perineum, which are in direct contact with the napkin or incontinence pad. They tend to regress spontaneously over a few weeks and occasionally leave scars.

Fig. 12.18 Papuloerosive dermatitis: there are multiple ulcerated papules and nodules predominantly affecting the labia majora.

By courtesy of the Institute of Dermatology, London, UK.

Pathogenesis and histological features

The etiology of the process is unclear but occlusion, Candida infection and fluorinated corticosteroids have been implicated. The last, however, does not seem to be of importance in the incontinent elderly patient.

The histology is fairly non-specific and includes superficial ulceration, focal necrosis and a prominent mixed inflammatory cell infiltrate with granulomata and numerous lymphocytes and plasma cells. Hemorrhage and hemosiderin deposition can sometimes be present.

Differential diagnosis

In the elderly variant and, when appropriate, Crohn’s disease and infective granulomatous conditions may have to be excluded

Clinical features

The clinical features of lichen simplex chronicus presenting on genital and anal skin are identical to those seen at other sites of the body. The mons pubis or labium majus, scrotum and perianal skin are the usual sites affected. Giant forms (of Pautrier) occur, e.g., on the scrotum, giving a pineapple appearance (Fig. 12.19).

Fig. 12.19 Lichen simplex chronicus. Scrotum. Giant ‘pineapple’ lesion.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

Histological features

The histological features are discussed in detail elsewhere but lichenification is characterized by hyperkeratosis, hypergranulosis, uniform acanthosis, fibrosis of the papillary dermis and an unremarkable low-grade perivascular infiltrate of mononuclear leukocytes in the superficial dermis. At mucosal sites hyper- and orthokeratosis create a cornified layer, resulting in the clinical appearances of leukoplakia.

Clinical features

Seborrheic dermatitis is a very common pattern of eczematous disease associated with an abnormal hypersensitivity to the normal commensal cutaneous yeast, Pityrosporum ovale. It is discussed elsewhere. In addition to the classical sites, e.g., scalp (pityriasis capitis, dandruff), ears, glabella and brows, nasolabial folds, axillae, chest and back, the groin and penis can be involved. Indeed, this may be the sole site, leading to the patient presenting, with pruritus ani or balanoposthitis, to a dermatologist. Some patients may also have a tendency to psoriasis (‘sebopsoriasis,’ ‘seboriasis’). On the scalp, on the face, in the flexures and at anogenital sites, seborrheic dermatitis and psoriasis may be indistinguishable. Seborrheic dermatitis is very common in HIV infection. Diagnosis is achieved on clinical grounds and it is not usually necessary to do a biopsy. Pityrosporum spp will be seen in large numbers.

Histology is identical to seborrheic dermatitis occurring elsewhere. However, spongiosis can be more prominent.

Clinical features

Flexural psoriasis is the most common pattern seen in the anogenital region, with extension into the genitocrural folds and natal cleft (Figs 12.20–12.23). There are often difficulties clinically in distinguishing between psoriasis and seborrheic dermatitis. Genital and flexural disease may reflect koebnerization and is relatively common.¹ In the circumcised male the signs on the glans and distal penile shaft are similar to those of psoriasis at extragenital sites, whereas the appearances in the uncircumcised male are of balanoposthitis similar to flexural psoriasis.²

Fig. 12.20 Psoriasis: note the symmetrical, intensely erythematous eruption involving the groins, vulva and perineum. Scaling is typically absent in flexural disease. The sharply demarcated border is characteristic.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.21 Psoriasis: there are erythematous plaques on the glans penis.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.22 Psoriasis: in this example a slight scale is apparent.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.23 Psoriasis: note the erythematous and slightly scaly plaque affecting the perineum.

By courtesy of the Institute of Dermatology, London, UK.

Histological features

Histology is often unhelpful, as the changes can be quite non-specific. The typical features of psoriasis are rarely evident and the presence of secondary spongiosis may be very misleading.

Clinical features

Reiter’s disease or syndrome is part of the same continuum as psoriasis in genetically predisposed individuals.¹ Reiter’s syndrome is defined by the triad of arthritis, urethritis and conjunctivitis. The eponym is gradually losing favor in the face of more descriptive nomenclature and the term reactive arthritis is frequently used. It is precipitated by non-specific urethritis, bacillary or amebic dysentery and associated with HIV infection and the immunogenotype HLA B27.^2–6 The classical triad may occur together or develop in sequence, and a range of other symptoms may also be present. It has a worldwide distribution. Reiter’s syndrome most commonly affects men 20–30 years of age; the male to female sex ratio is approximately 10:1.¹ The syndrome is characterized by a relapsing course.⁴

The condition may follow an enteric or a urogenital infection.^7,8 Shigella dysentery was the first associated enteric infection to be recognized and the causative organisms were either Shigella flexneri or S. dysenteriae.⁹ Recently, Salmonella, Yersinia and Campylobacter have been reported preceding Reiter’s syndrome.^10–14

Sexually transmitted Reiter’s syndrome may occur with a nongonococcal or ‘non-specific’ urethritis.⁷Chlamydia trachomatis is isolated from the genitourinary tract in 40–60% of male cases; isolation is variable, however, and an indirect immunofluorescence test detects chlamydial infection in 90% of patients.^15,16Mycoplasma infection and Streptococcus viridans have also been implicated.^17–19 The condition has also been linked to the acquired immunodeficiency syndrome (AIDS).^20–22 Rare associations include Cyclospora, Cryptosporidium, intravesical bacillus Calmette-Guérin (BCG) immunotherapy, Gardnerella vaginalis, hepatitis B immunization and systemic interferon-alpha (IFN-α) treatment.^23–28

Reiter’s syndrome is more likely to occur in predisposed individuals. Human leukocyte antigen (HLA)-B27, which is thought to occur in up to 90% of patients, increases the risk of developing Reiter’s syndrome by 25 times; the disease is also more severe in HLA-B27-positive individuals.^4,29 HLA-B27 in patients with Reiter’s syndrome correlates with ankylosing spondylitis.⁴ Reiter’s syndrome develops in 20% of HLA-B27-positive individuals after a specific infective episode.³⁰ HLA-B27 is found in approximately 10% of the normal population. Recently, an association with HLA-B51 has been reported.³¹ Rarely, familial instances have been documented.³⁰ Therefore it appears that the disease is triggered in genetically predisposed individuals by an unknown mechanism precipitated by infection.

The genitourinary tract is virtually always involved in the form of urethritis, prostatitis, seminal vesiculitis and hemorrhagic cystitis. Urethral strictures also sometimes occur and females may develop cervicitis.

Bilateral mucopurulent conjunctivitis is the usual form of eye involvement occurring in up to 35% of patients, but occasionally iritis, iridocyclitis, keratitis or blindness occurs.³²

Weight-bearing joints and the larger ones (knees, ankles, feet and wrists) are involved by the arthritis, often together with sacroiliitis. Radiological changes include osteoporosis, erosions and loss of joint space, with multiple joints usually affected.^4,30 Periostitis often affects the metatarsals, the phalanges of the feet and the tarsal bones; occasionally, ankylosis develops in the small bones of the hands and feet. Ankylosing spondylitis, which is an important manifestation, correlates with a high erythrocyte sedimentation rate (ESR).³⁰

In the initial stages of the arthritis the clinical picture resembles that of an acute joint infection, settling to subacute involvement. Although the arthritis in Reiter’s syndrome usually recovers completely, chronic manifestations can sometimes occur; it is important to remember that arthritis may be the only symptom in recurrent episodes.

Skin lesions in Reiter’s syndrome may be similar to those of psoriasis. Cutaneous manifestations include hyperkeratotic cobblestone lesions on the palms and soles and occasionally affecting the trunk and extremities (Fig. 12.24). The lesions initially present as erythematous macules; over the course of several days these become hyperkeratotic waxy papules, with an erythematous halo covered by dry hyperkeratotic material. The papules are numerous and eventually coalesce to form thickened horny plaques. Pustular lesions of the palms and soles may also be evident (keratoderma blenorrhagicum) (Fig. 12.25).

Fig. 12.24 Reiter’s syndrome: there are bilateral keratotic papules and plaques affecting the soles of the feet.

By courtesy of R.A. Marsden, MD, St George’s Hospital, London, UK

Fig. 12.25 Reiter’s syndrome: in addition to keratotic papules there are pustular lesions, many of which have ruptured – keratoderma blenorrhagicum.

By courtesy of the Institute of Dermatology, London, UK.

Circinate balanitis, presenting as a moist superficial erosion, 2–4 mm across, may affect the glans penis and meatus (Figs 12.26–12.28). Superficial ulceration of the oral mucosa may also occur, together with reddening and a granular appearance of the surrounding mucous membrane.^4,5

Fig. 12.26 Circinate balanitis. Glans penis. Psoriasiform lesions.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

Fig. 12.27 Reiter’s syndrome: there are multiple erosions on the glans penis.

By courtesy of The Institute of Dermatology, London, UK.

Fig. 12.28 Reiter’s syndrome: in this patient there are scaly lesions on the glans penis.

By courtesy of the Institute of Dermatology, London, UK.

Stomatitis and nail dystrophy (indistinguishable from that of psoriasis) may be additional features.⁴ Weight loss is common.²⁰ Aortic incompetence is an important late complication and IgA nephropathy has been described in a number of patients.^4,33

As stated before, Reiter’s syndrome is very rarely reported in females, and the majority of cases recognized are in males.^34–38 Vulvitis has been described in a small number of case reports.^34–38 and in one case cervical lesions were seen.³⁷ The vulval lesions are erythematous and may be ulcerative, eroded or scaly, and often resemble mucocutaneous candidiasis. The cervical lesions were recorded as white papules.³⁷ There may be accompanying oral lesions.

Reiter’s syndrome may resolve spontaneously, but more often it is characterized by chronicity and recurrences.⁴ Rarely, it may prove fatal.⁴ Causes of death include aortic incompetence, atrioventricular block, terminal cachexia, systemic amyloidosis and iatrogenic effects.³⁹

Histological features

Essentially, just as the skin lesions of Reiter’s syndrome have psoriasiform morphology (Fig. 12.29), they have the same histopathology and ultrastructure as pustular psoriasis.⁴⁰

Fig. 12.29 Reiter’s syndrome: there is parakeratosis overlying a macropustule. The squamous epithelium shows psoriasiform hyperplasia. These features are indistinguishable from pustular psoriasis.

The epidermis is acanthotic with elongation and hypertrophy of the epidermal ridges and parakeratosis. The suprapapillary plates are thinned and there is infiltration of the epidermis by neutrophils, associated with vacuolation of superficial keratinocytes, together with the formation of spongiform pustules and microabscesses (Fig. 12.30). The inflammation extends into the adjacent underlying dermis where it is predominantly mononuclear. The histology is essentially identical to that seen in pustular psoriasis.² Therefore, close clinicopathological correlation is critical to establish a diagnosis. Occasional biopsies from typical lesions of patients with Reiter’s syndrome may disclose an underlying leukocytoclastic vasculitis.⁴¹

Fig. 12.30 Reiter’s syndrome: high-power view showing parakeratosis and a pustule.

A small number of patients presenting with skin lesions that histologically showed sterile neutrophilic folliculitis with perifollicular vasculopathy have been documented.⁴² The authors suggested that this histological pattern may be a marker of systemic disease. Associations may include Reiter’s syndrome, inflammatory bowel disease, Behçet’s disease, hepatitis B infection, scrofuloderma, connective tissue diseases and hematological dyscrasias. Patients present with systemic symptoms and variable skin lesions including folliculitis, vasculitis, acneiform eruptions, vesiculopustules and erythema nodosum-like features.

Early joint lesions are characterized by a neutrophil polymorph inflammatory cell infiltrate with little if any synovial changes. Older lesions show features suggestive of rheumatoid arthritis, including lymphoid aggregates, a perivascular chronic inflammatory cell infiltrate and synovial hyperplasia.³⁰

Differential diagnosis

Periodic acid-Schiff (PAS) and/or silver stains should always be performed to exclude a fungal infection which can show similar histological features.

Clinical features

Anogenital lesions may be found in up to 40% of patients with generalized disease. In some, however, the disease is restricted to the lower genital tract and/or the perianal region, and in these instances the diagnosis may be difficult to establish.^1,2 Lichen planus (LP) manifests the Koebner phenomenon which may partly explain the orogenital predilection.³ Genital lichen planus in children is exceptional.⁴

The lesions are typical, violaceous or white patches or areas of erythema and erosions. Wickham’s striae (frequently seen in oral involvement), although sometimes visible, are less often found on anogenital skin (Fig. 12.31). The erosive form of LP is commoner at anogenital sites and can lead to scarring and distortion of the architecture (Figs 12.32–12.34). The vulval vestibule and vagina and cervix may also be involved and sometimes the vagina and or the cervix are affected alone.^5–7 Perianal disease can lead to deep, painful fissuring and it is often the hypertrophic variant that involves this site. Women with oral lichen planus often have genital disease and they frequently have asymptomatic lesions.^8,9

Fig. 12.31 Lichen planus: perineal lesions showing conspicuous striae.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.32 Erosive lichen planus: bilateral erosions are present.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.33 Erosive lichen planus: there is extensive erosion of the glans penis.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.34 Vulval lichen planus: reticulated lesions of lichen planus extending into the perineum.

By courtesy of the Institute of Dermatology, London, UK.

The clinical variants of lichen planus affecting the anogenital skin are usually squamopapular with areas of erosion, hypertrophic and hyperpigmented flexural disease (Figs 12.35–12.39). In the male genital, LP can present as phimosis.^10,11 Adhesions are seen in the uncircumcised male, both transcoronal and subcoronal.

Fig. 12.35 Vulval lichen planus: in this example of resolving disease there are linear hyperpigmented lesions.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.36 Perineal lichen planus: typical papules with Wickham’s striae are present.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.37 Hypertrophic perianal lichen planus: chronic scratching has resulted in superimposed lichenification.

By courtesy of the Institute of Dermatology, London, UK.

Fig. 12.38 Penile lichen planus: there is involvement of the shaft and glans.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

Fig. 12.39 Penile lichen planus: the proximal shaft shows post inflammatory hyperpigmentation.

From Bunker C: Male Genital Skin Disease. Saunders Ltd./Elsevier 2004.

There is also an unusual variant of erosive LP in women that involves the oral gingivae, vulval vestibule and vagina, known as the vulvovaginal-gingival syndrome (Figs 12.40–12.42).^12,13 This can lead to severe vulval and vaginal scarring with vaginal adhesions, constriction bands and, in some cases, complete stenosis.¹⁴ A male equivalent to the vulvo-vaginal syndrome of Hewitt with chronic erosive gingival and genital lesions (genito-gingival syndrome) has been described.^15,16 Patients with genital lesions may have anal, oral, aural, conjunctival and esophageal involvement.^17–24 Those patients with predominantly mucosal disease clinically mimic mucous membrane pemphigoid but immunofluorescence studies are invariably negative. A case of paraneoplastic lichen planus with orogenital involvement and cicatrizing conjunctivitis in association with thymoma has been described.²⁵

Fig. 12.40 Vulvovaginal-gingival syndrome: there is extensive vestibular erythema and erosion with a surrounding delicate white scale.

By courtesy of the Institute of Dermatology, London, UK.