Soft Tissue Lesions of the Vulva and the Vagina

Abstract

With the exception of fibroepithelial stromal polyps, the entities covered in this section are uncommon. For this reason, a broad differential diagnosis must be considered when evaluating a soft tissue lesion in the vulvovaginal region. This differential can be narrowed by patient age (for instance, prepubertal vulvar fibroma and embryonal rhabdomyosarcoma in young women), clinical presentation (slow vs. rapidly growing mass, superficial vs. deep), and morphology (myxoid vs. fibromatous appearance; spindle vs. round tumor cells; obvious smooth muscle, adipocytic, fibroblastic/myofibroblastic, vascular, or Schwannian cell differentiation). Some lesions harbor characteristic genetic abnormalities (loss of the 13q14 locus in cellular angiofibroma and mammary-type myofibroblastoma or amplification of the 12q13-15 locus in atypical lipomatous tumor); in others, the diagnosis fully relies on histopathologic features. In any spindle cell proliferation of the vulva or vagina, spindled invasive squamous cell carcinoma and desmoplastic malignant melanoma should be considered and excluded through detailed examination and ancillary studies (immunohistochemistry, HPV testing). Entities included in this chapter are organized into benign, locally aggressive, and malignant categories (with the exception of smooth muscle tumors, which are covered together). The chapter emphasizes on lesions with anatomic predilection for the lower genital tract and likely derivation from specialized vulvovaginal stromal cells; while morphologic overlap exists among these lesions, their behavior and clinical management are indolent, with the exception of aggressive angiomyxoma. The latter, thus, should be always considered and excluded through careful assessment, radiologic correlation, and thorough margin assessment on excision material.