Recent developments in vulvovaginal pathology

Abstract

This review discusses recent developments in vulvovaginal pathology. A variety of morphologically bland mesenchymal lesions occur at this site with considerable histological and immunohistochemical overlap. Aggressive angiomyxoma exhibits HMGA2 immunoreactivity in approximately 50% of cases, and this nuclear transcription factor is emerging as a useful and relatively specific marker for aggressive angiomyxoma, although occasional vulvovaginal smooth muscle neoplasms are positive. HMGA2 is useful in the diagnosis of aggressive angiomyxoma and its distinction from mimics, in the evaluation of resection margins and in the assessment of the presence or absence of residual disease in re-excisions. Aggressive angiomyxoma is almost invariably positive with oestrogen and progesterone receptors, and there have been several reports of a dramatic reduction in size following gonadotropin releasing hormone agonist therapy. Recent series of the relatively newly described entities cellular angiofibroma and superficial myofibroblastoma of the lower female genital tract have expanded upon the morphological spectrum of these neoplasms. Recently described mesenchymal lesions at this site include massive oedema and prepubertal vulval fibroma. Gastrointestinal stromal tumours have been described as primary neoplasms in the vagina, and rectovaginal septum and extragastrointestinal stromal tumour should be added to the differential diagnosis of a vulvovaginal mesenchymal lesion. Many mesenchymal lesions in the vulvovaginal region exhibit immunoreactivity with both CD34 and desmin, a somewhat unusual immunophenotype in mesenchymal lesions at other sites. It is now established that there are two distinct types of vulval intraepithelial neoplasia (VIN), most commonly termed classic and differentiated VIN, the former associated with human papillomavirus (HPV) infection. There are two corresponding types of vulval squamous carcinoma with HPV-associated and non-HPV-associated variants, the latter often arising in a vulval dystrophy and associated with p53 mutation. However, in some cases there is clinicopathological overlap between HPV-associated and non-HPV-associated squamous carcinomas, and immunohistochemistry with p16 is more reliable than morphology in predicting the presence of HPV. There have been new developments regarding Paget's disease of the vulva with the identification of markers that are useful in diagnosis and evidence that the neoplastic cells represent a proliferation of adnexal stem cells residing in sebaceous units. The newly described entity vaginal tubulo-squamous polyp typically exhibits immunopositivity with prostatic markers, possibly indicating derivation from displaced periurethral Skene's glands.