Kristiana Gordon The lymphatic system comprises a network of lymphatic vessels and lymph nodes that drain materials from tissue spaces that cannot directly return to the bloodstream. These include capillary fluid filtrate, proteins, immune cells (macrophages, lymphocytes, and dendritic cells) and malignant cells [1]. Lymph is the name given to the interstitial fluid formed from the blood capillary filtrate which then drains via the lymphatic system. The lymphatic system has several functions including maintenance of fluid homeostasis by returning lymphatic fluid from interstitial spaces to the blood circulation and maintaining immune function with the help of lymphoid organs. The lymphatic system has also been shown to play a role in disease, such as inflammatory disorders and cancer metastasis [2]. Failure of lymphatic drainage results in the accumulation of lymph within the body’s tissues. When it affects peripheral tissues, it is called lymphoedema. Lymphoedema is an under‐recognised, chronic condition that may lead to debilitating physical and psychological morbidity, and most physicians receive minimal training in this field. Recurrent infections complicate many cases of lymphoedema, regardless of the underlying cause, and add to the burden of disease experienced by patients. The prevalence of lower limb, let alone genital, lymphoedema remains largely unknown as there has been little interest in the disease. The incidence of genital lymphoedema, even within cohorts of cancer patients, has rarely been discussed in the literature. However, it is likely to occur in many women receiving gynaecological cancer treatment, given the significant risk of developing lymphoedema from other cancers. For example, a risk of 5–41% of developing arm lymphoedema is suggested after breast cancer treatment with axillary lymph node removal with or without radiotherapy [3, 4]. Clearly there is a need to identify women with genital lymphoedema and recognise any additional risk factors that could be addressed to reduce the incidence of this disease. The drainage pathways of both inguinal regions must fail or become damaged for genital lymphoedema to occur as a result of inguinal nodal pathology. This is because the genital tissues possess the option of bilateral lymph node drainage, unlike the lower limbs. Blockage of local dermal or subcutaneous lymphatics (e.g. by anogenital granulomatosis) can also result in genital lymphoedema. Failure of the lymphatic system to function adequately leads to the accumulation of protein‐rich lymphatic fluid within interstitial spaces, manifesting as lymphoedema and its associated skin changes. Lymphoedema may be classified as either secondary or primary in origin. Secondary lymphoedema results from occlusion of, or damage to, the lymphatic system from extrinsic factors such as infection, surgical lymphadenectomy, and radiotherapy. Primary lymphoedema occurs as a result of a genetically determined developmental abnormality of the lymphatic system and is much rarer than secondary lymphoedema [5]. Secondary lymphoedema occurs when one or more factors have impaired a previously normal lymphatic system. It may occur as a result of gynaecological or skin cancer obstructing the flow of lymph either as a direct result of disease bulk or local infiltration, or more commonly as a result of its treatment, including lymph node removal and/or radiotherapy [6]. Non‐malignant causes of genital lymphoedema include accidental or surgical trauma to the lymphatic system, severe obesity (due to the physical obstruction of bilateral groin lymph drainage by a morbidly obese abdomen), and inflammatory and infective diseases. However, more than one factor may be implicated in the onset of genital lymphoedema (Figure 33.1) [7]. Genital lymphoedema has been reported in women who have undertaken intensive cycling and has been termed ‘bicyclist’s vulva’ (see Chapter 54). It typically presents with asymmetrical labial swelling but no lower limb involvement [8]. Lymphoscintigraphy imaging has shown lymphatic drainage abnormalities thought to occur as a result of repeated compression of the inguinal lymphatic vessels from the saddle [9]. Figure 33.1 Secondary genital lymphoedema. There is pitting oedema of the mons pubis and labia due to a combination of anogenital granulomatosis, flexural psoriasis, and previous hidradenitis suppurativa. Obesity has complicated the clinical picture and exacerbated the lymphatic impairment. Inflammatory causes of genital lymphoedema include anogenital granulomatosis (essentially a cutaneous form of Crohn’s disease affecting vulval tissues) and hidradenitis suppurativa, where associated tell‐tale skin signs provide the clinician with diagnostic clues. These include subtle erythema of the labial skin or indurated erythematous plaques in anogenital granulomatosis or nodules, abscesses, and scars in hidradenitis suppurativa [10, 11]. In addition, anogenital cutaneous involvement should be considered in anyone with a history of gastrointestinal Crohn’s disease, and careful examination of the anus and natal cleft can reveal clues. Although it is possible to determine the underlying inflammatory cause from the history and examination in some cases, a skin biopsy may be needed to confirm the diagnosis. For example, a patient with anogenital granulomatosis may report intermittent genital swelling and erythema but no known history of gastrointestinal Crohn’s disease. A biopsy of affected tissue should be undertaken to confirm the presence of non‐caseating granulomas in the dermis before immunosuppressive therapy is commenced. In this scenario, lymphoedema may occur as a result of intralymphatic granulomatous inflammation causing partial or complete occlusion of lymphatic drainage [12]. Identification of an underlying inflammatory cause of lymphoedema is vital as treatment with intra‐lesional steroids or immunomodulators can significantly improve the prognosis [13, 14]. Inflammatory causes should be suspected in a woman with genital lymphoedema in the absence of lower limb involvement. Infections known to cause genital lymphoedema include filariasis, the most common cause of lymphoedema worldwide (affecting 40 million individuals). This tropical disease is rarely seen in the United Kingdom but should be suspected in someone with asymmetrical lower limb and genital lymphoedema with a significant travel history [15]. Other infections causing obstruction of genital lymphatic drainage include donovanosis and lymphogranuloma venereum [16, 17]. Severe or recurrent cellulitis can also cause genital lymphoedema, presumably due to recurrent damage of the fragile lymphatic vessels. However, it is likely these women have a mild underlying primary lymphoedema/lymphatic impairment that predisposed them to cellulitis in the first place. Primary lymphoedema of the genitalia almost always occurs in association with lower limb swelling (either unilateral or bilateral). It should be considered in a child or young woman presenting with genital swelling. An underlying genetic cause is highly likely, and patients should be referred to a specialist primary lymphoedema clinic for further investigation and management. Primary lymphoedema is not one disease, but an umbrella term for many different conditions that present with swelling or lymphoedema. To date there are four subtypes of primary lymphoedema that cause genital lymphoedema for which mutations have been discovered [5]. These are shown in
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Lymphatic Abnormalities and the Vulva
Epidemiology
Pathophysiology
Secondary Lymphoedema
Primary Lymphoedema
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