27
Other Inflammatory Dermatoses

Fiona M. Lewis

Nodular prurigo

Nodular prurigo is a condition in which intensely itchy and persistent nodules develop (Figure 27.1). The cause is unknown, and it can be challenging to treat as there is a difficult itch–scratch cycle to break. It most commonly affects the limbs but it has been reported on the vulva [1], and it is important to distinguish it from malignancy [2].

Intertrigo

Intertrigo is an inflammatory dermatosis seen in the flexures caused by occlusion and friction that is inevitable at these sites. The inguinal folds are often involved (Figure 27.2). Secondary infection with candida, staphylococci, or streptococci is common. An increased body mass index, diabetes, and inability to self‐care adequately are important risk factors [3]. It generally responds well to a mild topical steroid with appropriate antibiotic treatment if infected. Non‐responsive areas should be biopsied to exclude less common intertriginous eruptions or nutritional deficiencies which often occur at these sites.

Autoimmune progesterone dermatitis

This is an autoimmune reaction to endogenous progesterone. The cutaneous lesions occur on a cyclical basis during the luteal phase when the progesterone levels increase. The morphology can vary from urticaria to erythema multiforme–like lesions, and vulval involvement mimicking a fixed drug eruption on the labia majora has been reported [4]. A variety of treatments are used, but the most effective is to inhibit the secretion of natural progesterone by suppressing ovulation [5].

Malacoplakia

This is a rare inflammatory condition where there is an abnormal response to bacterial pathogens. It is more common in the immunosuppressed.

Epidemiology

It is more common in females than in males (2:1) but can occur at any age.

Photo depicts nodular prurigo. Intensely pruritic nodules on lichen simplex. — **Figure 27.1** Nodular prurigo. Intensely pruritic nodules on lichen simplex.

Photo depicts intertrigo in right inguinal fold. — **Figure 27.2** Intertrigo in right inguinal fold.

Pathophysiology

It is due to macrophage dysfunction, which results in an inadequate histiocytic response. The primary infection is with Escherichia coli, Klebsiella, and Proteus species in 90% of cases.

Histological features

The histological appearance is typical and includes sheets of macrophages with an eosinophilic foamy cytoplasm (von Hansemann cells) and characteristic intracytoplasmic ‘targetoid’ inclusions (Michaelis–Gutmann bodies). The inclusion bodies can be demonstrated with Perls’ iron, Prussian blue, and Periodic acid–Schiff stains. A Gram stain may also reveal intracellular and extracellular bacteria.

Clinical features

About 40% of cases of malakoplakia involve the genital area [6]. Typically, papules, nodules, ulcers, and draining sinuses may be found [7]. Vaginal involvement frequently presents with bleeding.

Differential diagnosis

The clinical differential diagnosis includes Crohn’s disease, other granulomatous conditions, and malignancy.

Complications

Large lesions can obstruct the urinary system with functional sequelae [8].

Associated disease

Primary or acquired immunodeficiency has been noted in nearly 40% of patients [9]. This must be investigated if not apparent at diagnosis.

Treatment

Long‐term antibiotics and surgery are required.

Reiter’s syndrome (reactive arthritis)

Reiter’s syndrome is now termed reactive arthritis and is a systemic illness with seronegative arthritis secondary to an infection elsewhere, most commonly of the genitourinary or gastrointestinal tract [10]. Several infections, including those that are sexually transmitted, have been implicated as causative factors. HLA B27 is often related. Genital aphthous ulceration is seen in over 50% cases, and a psoriasiform eruption, termed circinate balanitis in males, is seen. This is much rarer in females, but it has been described [11, 12].

Vulval aphthous ulcers

There can be a great deal of confusion with the classification of aphthous ulcers. Some authors include all aphthae, whatever the cause, together, but there are distinct clinical patterns of disease which are part of the spectrum of aphthous ulceration. It is more helpful to use these.

Recurrent aphthous ulcers – can affect oral mucosa most commonly, but vulval ulcers can occur at the same time or separately.
Non‐sexually acquired genital ulcers (Lipschutz type) – linked to infection (see Chapter 19). Most of the reported cases of aphthae are examples of these.
Aphthae associated with systemic disease, for example, inflammatory bowel disease.
Behcet’s syndrome.

Recurrent oral aphthous ulcers are very common, affecting the majority of the population at some point in their life. The mild form is self‐limiting and may not require any treatment.

Some patients have major aphthae, with larger and more severe lesions which scar (Figure 27.3). These can also affect the vulva.

Epidemiology/genetics

The onset is usually in childhood or adolescence, and there are no features of systemic disease. There may be a family history, and several HLA links have been reported [13].

Pathophysiology

The aetiology is uncertain. Several theories are postulated in recurrent aphthous stomatitis including vitamin deficiencies, microbe‐induced hypersensitivity, stress, and allergy [14].

Photo depicts major oral aphthous ulcer. — **Figure 27.3** Major oral aphthous ulcer.

Histological features

The histology is non‐specific.

Clinical features

The vulval ulcers are sharply defined with a yellow sloughy base and a red halo like rim. They are most commonly found on the inner aspects of the labia majora (Figure 27.4) or minora or at the introitus. Aphthous ulcers can be minor (<1 cm), major (>1 cm), or herpetiform where there are grouped lesions, but these have no relationship to herpes simplex infection. Larger lesions take longer to heal and may scar.

Differential diagnosis

The major differential diagnoses for the vulval ulcers are herpes simplex, Stevens–Johnson syndrome, and Behcet’s syndrome.

Treatment

Multiple topical and systemic therapies have been used. Topical corticosteroids, applied in an adhesive base, and tetracyclines are useful for vulval ulcers. Topical local anaesthetic agents, such as 5% lidocaine ointment, may also have a role. For patients with recurrent disease, systemic agents including colchicine, dapsone, and thalidomide have been used. Thalidomide can be very effective [15], but in view of its devastating teratogenic effects is very limited in its use for vulval ulcers.

Photo depicts healing aphthous ulcer lower-right labium majus. — **Figure 27.4** Healing aphthous ulcer lower‐right labium majus.

Prognosis and follow‐up

The lesions will often relapse and recur.

Behcet’s syndrome

Behcet’s syndrome is now recognised as a multisystem, inflammatory syndrome which may have different subtypes. In 1990 diagnostic criteria were outlined by an International Study Group for Behcet’s syndrome. The diagnosis was made when a patient had recurrent oral ulceration in combination with at least two of the following: recurrent genital ulceration, eye lesions, cutaneous lesions, or a positive pathergy test (sterile pustules following trauma such as a needle prick). These have been refined by an international committee, and the newer criteria involve a point system where oral and genital ulcers score 2 points each, and other cutaneous lesions, vasculitis, central nervous system involvement, and pathergy each score 1 point. A score of 4 or more points is consistent with a diagnosis of Behcet’s syndrome, and this has been shown to have a better specificity than the previous diagnostic criteria [16].