Zlatko Marusic and Eduardo Calonje The most common malignant tumour of the vulva is a squamous cell carcinoma (SCC; see Chapter 43). This chapter discusses the other types of malignancy that are much less common but can be seen on the vulva. The entities of desmoid tumour and aggressive angiomyxoma are also included here, as although they are benign, they exhibit locally aggressive behaviour. Basal cell carcinomas (BCCs) constitute 2–5% of vulval malignancies [1]. In a systematic review of 446 published cases, the mean age of onset was 70 years [2], and they most commonly occur in Caucasian women. The cause of genital BCCs is not known, although cases have been described in basal cell naevus syndrome (Gorlin’s syndrome) [3] and after pelvic radiotherapy [4]. Some have been reported in association with other conditions, including lichen sclerosus and extra‐mammary Paget disease [5]. Most tumours arise on the labia majora, but they may also occur in the fourchette, mons pubis, periurethral region, or clitoris. There is wide variation in presentation. They may be nodular or flat, shiny plaques which may be ulcerated (Figure 45.1). Pigmentation in vulval BCCs is very common. Symptoms include pain, ulceration, and bleeding. They are usually less than 2 cm, but do grow slowly without treatment. The features seen with dermoscopy are leaf‐like areas and fine telangiectasia without the features of melanocytic lesions [6,7]. Although not widely available, reflectance confocal microscopy may be of use in pre‐operative diagnosis [8]. The appearance of a vulval BCC is identical to that seen elsewhere. The commonest patterns are superficial and nodular in which multiple invasive nests of variable size appear to bud off or extend from the basal portion of the epithelium (Figure 45.2), and the morphoea‐like pattern in which basaloid cells form cords that elicit a dense fibrotic desmoplastic stroma that may be hyalinised (Figure 45.3). Gland‐like spaces are not uncommon, but tumours with a predominance of these spaces, the adenomatoid pattern, are uncommon [9]. The tumour cells closely resemble those of the overlying basal epithelium or periphery of the outer root sheath of hair follicles. The cells have scant cytoplasm and small hyperchromatic elongated nuclei. Unlike basaloid squamous carcinomas, there is usually little pleomorphism; although mitotic figures are present, they are usually inconspicuous, and there is characteristic palisading of the nuclei at the periphery of the nests, and an absence of overlying atypia, the intraepithelial neoplastic cells being confined to the basal and parabasal cell layers of the surface epithelium. The stroma frequently has a basophilic myxoid appearance, and there is a variable degree of chronic inflammation. Factors such as tumour size, thickness, and distance from the margin seem to be superior predictors of recurrence than the histological [10]. BCCs of the vulva rarely metastasise, but they can recur and cause extensive local destruction. In the review of 446 cases, 23 (5.1%) recurred and 12 (2.7%) metastasised [2]. These were mainly nodal metastases, but distant disease in bone [11] and lungs [12] have been recorded. The risk is greater in older patients with larger and infiltrating primary lesions. The most effective treatment is Mohs micrographic surgery [2,13]. Several malignant tumours of the anogenital glands have been described [14]. Adenocarcinoma is the most common. Isolated case reports of tumours such as apocrine carcinoma, eccrine mucinous carcinoma, microcystic adnexal carcinoma, and miscellaneous rare sweat gland tumours in the vulval area are most likely derived from the anogenital mammary‐like glands and probably do not deserve to be viewed as separate entities. The same probably applies to primary adenocarcinoma and adenosquamous carcinoma of the vulva that is not associated with Bartholin’s gland. However, it should be noted that the presence of an adenocarcinoma with gastrointestinal‐type histology in the vulva should prompt a search for a primary in the sigmoid colon or rectum and an investigation for metastatic tumours at other sites. Adenocarcinoma of the anogenital glands tends to occur in post‐menopausal women with a mean age of 59 years. The lesions most commonly arise in the labia majora with a mean size of 2.5 cm [15]. They form a subepithelial mass in the interlabial sulcus or adjacent labia. The tumours most commonly have a microscopic appearance identical to that of mammary duct carcinomas and are composed of infiltrating cords, nests, and/or tubules of cuboidal cells to rounded malignant cells with a moderate amount of amphophilic to eosinophilic cytoplasm and a central nucleus that often has a prominent nucleolus. Anogenital glands may be present at the periphery, and, in the older literature, these were mistaken for ectopic breast tissue. Like mammary ductal carcinomas, they are usually positive for oestrogen receptor protein, and frequently positive for progesterone receptor protein and gross cystic disease fluid protein (GCDFP). Some cases show PIK3CA mutations [16]. The tumours initially metastasise to the ipsilateral groin lymph nodes. Figure 45.1 Vulval basal cell carcinoma. Pearly nodule on right labium majus. Figure 45.2 Superficial basal cell carcinoma with peripheral palisading arising from the basal epithelium with normal maturation above. Figure 45.3 Morphoeic basal cell carcinoma with infiltrating tumour cords. Treatment of adenocarcinomas of anogenital glands is surgical excision and groin lymph node dissection on the ipsilateral side. These tumours can be very difficult to distinguish from mammary ductal carcinoma, and so the erroneous diagnosis of metastatic breast cancer is easily made. Although the vulva may be a site for metastatic disease, it is rarely a site for the initial presentation of the primary disease. Consequently, if an isolated vulval carcinoma with histological and immunohistochemical features identical to that of breast ductal carcinoma is seen, and if metastatic disease is clinically confined to the ipsilateral lymph nodes, a diagnosis of primary anogenital carcinoma is warranted, and subsequent investigations should be limited to staging the patient. Malignant smooth muscle neoplasms of the vulva take two forms. One is that of a clearly sarcomatous tumour with considerable pleomorphism and mitotic activity, while the other closely resembles a leiomyoma but nevertheless behaves in a malignant fashion. The clearly malignant neoplasms may or may not be easily recognisable as being of smooth muscle origin, and in doubtful cases a positive staining reaction for smooth muscle actin, desmin, and H‐caldesmon is of considerable diagnostic value. Leiomyosarcomas of the vulva, showing unmistakable histological evidence of malignancy, are rare [17,18]. They occur in middle‐aged and older women, and the history is of an enlarging mass, most commonly in the labia majora. Lesions may grow rapidly during pregnancy [19]. All the tumours discussed so far are clearly malignant and can be regarded as leiomyosarcomas of high‐grade malignancy. However, the question of malignancy in vulval smooth muscle neoplasms has been looked at from a quite different viewpoint [20]. Tavassoli and Norris studied 32 vulval neoplasms that were quite clearly of smooth muscle nature, and attempted to define criteria for their recognition which, although not having any obvious potential for metastasis, would nevertheless tend to behave as low‐grade leiomyosarcomas and recur locally after initial resection. They concluded that those neoplasms measuring more than 5 cm in diameter, having infiltrating margins, and containing more than 5 mitotic figures per 10 high‐power fields are very likely to recur. Furthermore, tumours showing all these three features should be regarded as leiomyosarcomas, irrespective of the degree of cellular atypia. They considered that neoplasms showing any two of these features should be regarded as low‐grade leiomyosarcomas. Other authors generally agreed with these criteria but considered the rate of mitotic activity as equal to or more than 5 per 10 high‐power fields, and moderate to severe cytological atypia was another feature added to the diagnostic criteria [21]. If a tumour had three of the four criteria, it should be regarded as a leiomyosarcoma. If only one of these criteria was present, the neoplasm should be regarded as a leiomyoma whereas if two were noted the tumour should be classed as an atypical leiomyoma. They considered that both leiomyomas and atypical leiomyomas should be excised conservatively while neoplasms classed by their criteria as leiomyosarcomas should be excised with wide negative margins. Smooth muscle tumours of the vulva can, however, recur in the absence of all the morphological features suggestive of aggressive behaviour, and all leiomyomatous neoplasms should therefore be treated by complete local excision. Histological criteria applied in uterine pathology seem to classify the malignant potential of vulvovaginal smooth muscle tumours more appropriately than site‐specific criteria [22]. A few myxoid leiomyosarcomas of the vulva have been recorded [23], although this is not a particular site of predilection for this type. Treatment is by complete surgical excision followed by radiotherapy in most cases. Recurrence is common with surgery alone. Chemotherapy may reduce the risk of relapse [24], but as with unusual tumours, there are no clear guidelines. Rhabdomyosarcomas are tumours that arise in foetal mesenchymal tissue and can occur at sites where there is no striated muscle. In a large series of 144 cases affecting the genital tract, 50% affected the vulva or vagina [25]. About 80% of rhabdomyosarcomas are diagnosed in childhood or the early teens, with the median age of presentation in the genital tract being 16 years. They can occur in adults [26], and the prognosis in the older age groups is not as good as in children. The majority present with firm nodules in the labia, but if affecting the clitoris, can be mistaken for clitoromegaly and disorders of sexual differentiation [27]. Polypoid lesions can also occur. The most common type in children is the embryonal subtype, and only a few cases of alveolar rhabdomyosarcoma of the vulva have been reported [28]. The prognosis is similar to that of alveolar rhabdomyosarcoma presenting elsewhere. Pleomorphic rhabdomyosarcoma is exceptional in the vulva [29]. Three histological types of rhabdomyosarcoma are recognised: embryonic, alveolar, and pleomorphic. Desmin and muscle actin expression serve as markers for rhabdomyosarcomas, whereas immunocytochemical demonstration of the MyoD1 gene product and myogenin are highly specific for striated muscle differentiation [30]. Embryonic rhabdomyosarcomas tend to form oedematous polypoidal masses and usually have a myxoid stroma in which pleomorphic spindle‐shaped or rounded cells are characteristically widely scattered. Alveolar rhabdomyosarcomas are formed principally of rounded cells that are separated into nodules by fibrous septa; central necrosis within these lobules imparts an alveolar pattern to the tumour. Pleomorphic rhabdomyosarcoma is characterized by sheets of large, atypical, and frequently multinucleated polygonal eosinophilic cells with an occasional component of undifferentiated round to spindle cells [28]. The treatment is complete surgical excision, followed by radiotherapy and chemotherapy to treat any micrometastases [25]. Outcomes are generally better in younger patients and in those with embryonal histology and negative lymph nodes. Desmoid tumours are forms of local fibromatosis and rarely affect the vulva. They can become very large and infiltrate adjacent tissues. Only a handful of cases of desmoid tumour of the vulva have been recorded, one of which occurred during pregnancy and one affected Bartholin’s gland [31]. Tumours are ill‐defined, infiltrative, and composed of elongated, slender, bland spindle‐shaped cells, with low mitotic activity. B‐catenin is expressed in the nuclei of tumour cells. Complete excision is needed as they usually recur and can be locally aggressive. Dermatofibrosarcoma protuberans (DFSP) is a soft tissue tumour involving the dermis, subcutaneous fat and sometimes deeper structures. Cases involving the vulva are rare. In a review of 54 published cases of vulval DFSP, the mean age at diagnosis was 45 years [32]. The labia majora are the most common site affected, with slowly growing lesions that are often present for years. They may measure anything up to 8 cm in diameter. The overlying skin may be ulcerated. The tumour is infiltrative and formed of plump fibroblastic cells arranged in a distinctly storiform pattern with little pleomorphism and sparse mitotic figures (Figures 45.4a,b). Fibrosarcomatous change was noted in two vulval neoplasms [33,34].
45
Other Malignant Vulval Tumours
Tumours of epithelium
Basal cell carcinoma
Clinical features
Histological features
Management
Tumours of anogenital mammary glands
Anogenital gland carcinoma
Clinical features
Histological features
Management
Tumours of smooth muscle
Leiomyosarcoma
Clinical features
Histological features
Management
Tumours of striated muscle
Rhabdomyosarcoma
Clinical features
Histological features
Management
Tumours of fibroblastic tissue
Desmoid tumour
Clinical features
Histological features
Management
Dermatofibrosarcoma protuberans
Clinical features
Histological features
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