16 Any dermatological condition has a potential to occur on the genital skin but there are some where involvement at this site is more common (see Table 16.1) and these are discussed here. Table 16.1 Other dermatoses. This is a rare blistering disorder inherited as an autosomal dominant trait. The lesions start in the 30s and tend to improve with age but the course is relapsing and remitting. The bullae are intraepidermal and recurrent vesicles and erosions occur in the flexures. The erosions may be crusted, forming plaques with a scaly border (Figure 16.1) and are often initially mistaken for intertrigo or candida infection. The problem is exacerbated by friction, heat and moisture. The outer vulva and inguinal folds are therefore commonly affected. Figure 16.1 Hailey‐Hailey disease – pruritic papules on labium majus. Histology shows acantholysis in the suprabasal layers of the epidermis. Squamous cell carcinoma has been reported to occur but this is rare. Simple measures include reducing frictional factors with weight loss being an important part of management. Control of any secondary infection is vital and long‐term antibiotics may be required in some patients. Emollients and a moderately potent topical steroid can be helpful in mild disease. Topical tacrolimus has been reported to be of benefit but a case of squamous cell carcinoma developing after treatment has been reported and it should therefore be used with caution. Other options include photodynamic therapy, CO2 laser, alefacept and botulinum toxin, but the evidence for these treatments is limited. The Hailey‐Hailey disease society: In autoimmune bullous disease (Table 16.2), autoantibodies react against a component of the epidermis or basement membrane to produce a split in the epithelium, which presents as blistering or erosion. The genital area is mainly involved in bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP), where about half of the patients will have some vulval lesions. In linear IgA disease, 80% of children will have vulval involvement and it can present at this site. Pemphigus vulgaris (PV) and epidermolysis bullosa acquisita (EBA) may involve the vulva and vagina less commonly. The diagnosis is made by taking a skin biopsy and sending for direct immunofluorescence (see Chapter 5) as the patterns seen are specific for each disease. In bullous pemphigoid, mucous membrane pemphigoid and Linear IgA disease, tense blisters are seen (Figure 16.2) as the split in the skin is deep at the level of the dermo‐epidermal junction. In pemphigus, blisters are rarely seen as the split is very superficial occurring in the epidermis. Erosions are therefore common. Figure 16.2 Bullous pemphigoid – tense bullae. Table 16.2 Clinical features and immunofluorescence patterns in auto‐immune bullous disease. Figure 16.3 Bullous pemphigoid: direct immunofluorescence shows a strong linear deposition of IgG (shown) and C3 both along the basement membrane zone and the roof of the subepidermal blister (courtesy of Dr C. Stefanato) Figure 16.4 Pemphigus: Direct immunofluorescence shows a positive intraepidermal intercellular deposition of IgG (shown) and C3. Please notice the intraepidermal acantholytic blister (courtesy of Dr C Stefanato). Mucous membrane pemphigoid (cicatrical pemphigoid) is particularly important as the genital lesions lead to scarring (Figure 16.5), which can be difficult to distinguish from lichen planus and lichen sclerosus. The oral lesions are those of a desquamative gingivitis (Figure 16.6). Urethral and vaginal stenosis can occur and perianal lesions lead to pain on defaecation. Ocular involvement can be severe and lead to symblepharon and expert ophthalmological intervention is required in these patients. Figure 16.5 Mucous membrane pemphigoid – scarring and erosions. Figure 16.6 Mucous membrane pemphigoid – desquamative gingivitis. In pemphigus vulgaris, vaginal lesions may occur. These can be erosive and scarring is therefore a potential problem. Significant vaginal disease can present with a discharge. The vulval lesions are those of erosions and superficial ulceration (Figure 16.7). Figure 16.7 Pemphigus vulgaris of the vulva. A fixed drug eruption causes the same lesions at the same site every time the drug is ingested and the genital area is one of the preferential sites for this type of drug reaction. It occurs within hours of taking the causative medication and itchy, erythematous lesions develop, which rapidly progress to blisters and erosions. The problem may be intermittent as common agents that cause a fixed drug eruption are analgesics and antibiotics. A very careful history is often required to identify the trigger. Occasionally a challenge test is needed to confirm the diagnosis. The lesions may heal with postinflammatory hyperpigmentation. The treatment is avoidance as the problem will recur with every exposure to the drug. DermNet: Erythema multiforme is a cutaneous reactive process either to a drug or infection (most commonly herpes simplex) where typical target lesions are seen. Stevens–Johnson syndrome is a severe form of this where mucosal disease is present in addition to the cutaneous lesions.
Other Dermatoses
Example
Genetic disorders
Hailey–Hailey disease
Autoimmune bullous disease
Bullous pemphigoid
Pemphigus vulgaris
Mucous membrane pemphigoid
Bullous dermatosis of childhood
Drug eruptions
Fixed drug eruption
Stevens–Johnson syndrome
Toxic epidermal necrolysis
Manifestations of underlying disease
Necrolytic migratory erythema
Acrodermatitis enteropathica
Inflammatory ulcers
Aphthous ulcers
Behcet’s disease
Lipschtuz ulcers
Others
Graft‐versus‐host disease
Zoon’s vulvitis
Vulvo‐vaginal adenosis
Langerhans cell histiocytosis
Genetic disorders
Hailey–Hailey Disease (Familial Benign Chronic Pemphigus)
Management
When to refer
Practice points
Further reading
Useful Web Site for Patient Information
Auto‐Immune Bullous Disease
Age
Clinical features
Immunofluorescence
Bullous pemphigoid
Elderly
Tense blisters
Linear IgG and C3 at basement membrane (Figure 16.3)
Mucous membrane pemphigoid
Adults, rare in children
Vulval and vaginal lesions with scarring; ocular lesions
Linear IgG at basement membrane
Pemphigus vulgaris
Adults, usually middle aged
Flacid, painful erosions; vaginal disease can cause a discharge
IgG between keratinocytes in epidermis (Figure 16.4)
Linear IgA disease
Children most commonly
Tense blisters, may be clustered in children.
IgA at basement membrane
Epidermolysis bullosa acquisita
Rare, mainly adults
Tense blisters
Practice points
Further Reading
Drug Eruptions
Fixed Drug Eruption
Common Drugs Causing a Fixed Drug Eruption
Further Reading
Useful Web Site for Patient Information
Stevens–Johnson syndrome
Symptoms
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