Eczema and Allergic Reactions

Eczema and Allergic Reactions

Fiona M. Lewis

Eczema is one of the most common skin conditions. It is due to defects in the epidermal barrier leading to the typical inflammatory features of erythema and dryness. The term eczema derives from the Greek ‘to boil over’ and in its acute form can be vesicular. In more chronic disease, the skin becomes thickened with excoriations and fissuring. The typical histological features are epidermal spongiosis (with intraepidermal vesicles in acute cases), acanthosis and a dermal lymphohistiocytic infiltrate.

There are many different types of eczema, but the common types to affect the vulva are shown in Table 22.1. There can be a great tendency to overdiagnose eczema and to use the term for any red lesions on the vulva. It is therefore important to distinguish between the different clinical patterns, as there are variations in management strategies and prognosis. Although the terms eczema and dermatitis are synonymous, ‘dermatitis’ tends to be used to describe cases where the cause is an exogenous agent applied to the skin.

Endogenous eczema

Atopic eczema

The common type of eczema affecting children and adults generally affects the flexures, but in fact, even when there is severe and widespread eczema elsewhere, patients rarely have any significant genital involvement. However, some may complain of pruritus, and minimal erythema can be seen. This is often found on the inner labia, perianally, and in the natal cleft. About 50% will find their symptoms worsen pre‐menstrually [1]. This will usually respond easily to the use of emollients and a weak topical steroid or tacrolimus ointment applied as needed.

Seborrhoeic eczema

This is a common type of eczema, particularly in young people. It usually affects the scalp, nasolabial folds, forehead, and inside the ears. Occasionally a ‘shield patch’ on the front of the chest is seen.


There is evidence that the yeast Pityrosporum ovale is involved in the pathogenesis of seborrheic eczema.

Histological features

The diagnosis is usually clinical, and histology can be non‐specific with hyperkeratosis and some neutrophil exocytosis. Yeast organisms are often seen on Periodic‐Acid Schiff (PAS) staining.

Clinical features

The symptom is mainly itch, but soreness can occur if there is associated fissuring. There may be subtle erythema and scaling on the outer labia majora with keratin debris in the interlabial sulci (Figures 22.1a,b). This is frequently mistaken for candidiasis. The inguinal folds and natal cleft may also be involved with ill‐defined and slightly scaly lesions. It is rare for the vulva to be the only site involved, and with careful examination of other sites, fine scaling on the scalp or inside the ears may be seen. Secondary infection sometimes occurs.

Table 22.1 Types of eczema affecting the vulva.

Endogenous Atopic


Lichen simplex
Exogenous Irritant

Allergic contact

Differential diagnosis

The main differential diagnosis, as with all types of eczema, is psoriasis and candidiasis.

Associated disease

Seborrhoeic eczema tends to be much more severe in the immunocompromised, so in those with widespread and non‐responsive disease, investigation for underlying immune compromise such as HIV infection should be undertaken.


A regular emollient used as a soap substitute is helpful, and there is usually a good response to a mild topical steroid applied on a short reducing regimen. Combination preparations including hydrocortisone and an antifungal can be particularly helpful so that the yeast organisms are also reduced in number.

Photo depicts (a) Seborrhoeic eczema with erythema affecting labia majora and minora. (b) Keratin debris in interlabial sulcus. Swabs for candida were negative

Figure 22.1 (a) Seborrhoeic eczema with erythema affecting labia majora and minora. (b) Keratin debris in interlabial sulcus. Swabs for candida were negative

Prognosis and follow‐up

There may be relapses from time to time, but these should respond well to repeated treatment.

Lichen simplex

Lichen is a term used to describe thickening and if papular may resemble the mossy surface of tree lichen. It should not be confused with the term lichenoid, which is used for histological patterns resembling lichen planus. Lichen simplex (sometimes referred to as lichen simplex chronicus) is a response to prolonged itching and subsequent rubbing seen once an itch–scratch cycle is set up.


Accurate figures for incidence are not known, but it is one of the commonest conditions seen in vulval clinics. A study of 183 vulval biopsies showed lichen simplex in 29% [2].


The clinical signs are the result of continuous scratching in response to itch. Some authors regard this as a variant of atopic dermatitis [3]. Psychological factors are important as lichen simplex is known to be linked with anxiety and stress [4,5].

Histological features

The histology shows hyperkeratosis, parakeratosis, acanthosis, a prominent granular layer, lengthened rete ridges, and a variable chronic inflammatory infiltrate (Figure 22.2). There is lamellar thickening of the papillary dermis and sometimes perineural fibrosis. All the epidermal components are hyperplastic, and the labelling index is increased. There may be some evidence of an underlying dermatological condition, and in Chan’s study 18 of 53 cases of lichen simplex showed lichen sclerosus and eczema as the initiating event [2]. They noted prominent fibroblasts and zones of pale epithelium as additional common features in lichen simplex. Multinucleated atypia is a non‐specific change sometimes found in lichenified skin [6].

Clinical features

The major symptom is itch, which is often enough to disturb sleep. This can start on the vulva and then spread to the perianal area, which is frequently involved (Figure 22.3). There is thickening mainly of the hair‐bearing outer labia majora (Figure 22.4) with a pale appearance secondary to the lichenification (Figure 22.5). More subtle signs include accentuated skin markings and reduction in the hair density from rubbing. Excoriations as a result of scratching may be seen, together with erosions and fissures (Figure 22.6). The signs are usually bilateral but can affect only one side (Figure 22.7), and when this occurs, it is usually more obvious on the side opposite the dominant hand. After resolution, post‐inflammatory pigmentary changes may occur.

Photo depicts histological features of lichen simplex.

Figure 22.2 Histological features of lichen simplex.

Photo depicts perianal lichenification.

Figure 22.3 Perianal lichenification.

Photo depicts lichen simplex with lichenification of the labia majora.

Figure 22.4 Lichen simplex with lichenification of the labia majora.

Photo depicts lichen simplex with thickening on inner labia majora with some pallor.

Figure 22.5 Lichen simplex with thickening on inner labia majora with some pallor.


The diagnosis is usually clinical but can be confirmed with biopsy if atypical. Dermoscopic features have been described with linear, serpiginous, and dotted vessels diffusely arranged in a white background which corresponds to the hyperkeratosis seen histologically [7]. Patch testing should be considered in chronic cases.

Photo depicts eczema – fissuring over perineum.

Figure 22.6 Eczema – fissuring over perineum.

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Nov 10, 2022 | Posted by in GYNECOLOGY | Comments Off on Eczema and Allergic Reactions

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