Vulvar Pruritus

Vulvar pruritus is a common symptom, which, if protracted, causes significant distress. Rapid resolution hinges on an accurate diagnosis. This chapter will outline a pragmatic clinical approach to a patient with pruritus, leading to an accurate assessment

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Vulvar Pruritus Nicholas Lawrance and Jennifer Yell

7.1

Introduction

Vulvar pruritus (itching) is common, affecting about 10% of women during their lifetime [1–3]. If persistent, significant morbidity can result in secondary skin thickening (lichen simplex), sleep disturbance and sexual and psychological difficulty. A systematic history and clinical examination will usually identify the cause. In those women with normal skin, pruritus may be due to an underlying medical cause.

7.2

Pathophysiology of Pruritus

Pruritus (itching, pruritus vulvae) is a poorly localized, unpleasant sensation which results in scratching. Pruritus and pain (vulvodynia) are different. Pruritus causes scratching. Pain causes withdrawal. Multiple neural pathways and molecular mechanisms are responsible for the sensation of pruritus. The precise relationship between pruritus and pain remains controversial, although there is evidence for separate pathways for pruritus and pain: a class of C-fibres, mechanically insensitive, slowly conducting and histamine responsive, support the theory of a separate pruritus pathway peripherally, along with a feline study showing a separate central pathway for N. Lawrance (*) · J. Yell British Society for the Study of Vulval Disease, Manchester, UK

Table 7.1  Classification of pruritus [4] Classification Pruritoceptive Neuropathic

Neurogenic

Psychogenic

Explanation Cutaneous, e.g. scabies, urticaria Due to lesions of afferent pathways of the nervous system, e.g. peripheral neuritis, nerve entrapment, brain tumours Due to centrally acting mediators which do not damage the central nervous system, e.g. morphine, opioid peptides of cholestasis For example, delusional parasitosis

pruritus, in which mechanically insensitive feline spinothalamic tract (STT) neurons were activated by histamine [4, 5]. Patients’ description of pruritus varies from burning, through pricking, to sensations of insects crawling over the skin. Vulvar pruritus, pain and/ or burning can co-exist. Pruritus has been formally classified as per Table  7.1. In formal studies clear measurement methods are required as per Table 7.2. The factors affecting pruritus are listed in Table 7.3.

7.3

Causes of Pruritus

The common causes of vulvar pruritus are listed in Table  7.4. In chronic pruritus [17], 1/3 of patients with generalized pruritus have an underlying systemic disease (see Table 7.5), 2/3 have skin disease-associated pruritus (which can include failure of the skin to retain water with age

© Springer International Publishing AG, part of Springer Nature 2019 J. Bornstein (ed.), Vulvar Disease, https://doi.org/10.1007/978-3-319-61621-6_7

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[18] and atopy), and about 7% are idiopathic (including psychogenic factors, such as anxiety and parasitophobia). Dermatology clinic review of 141 women with chronic vulvar symptoms identified eczema as the commonest reason for referral (54%), followed by lichen sclerosus (13%), chronic vulvovaginal candidiasis (10%), dysaesthetic vulvodynia (generalized spo